EPA 440/1-73/007
Development Document for
Proposed Effluent Limitations Guidelines
».
and New Source Performance Standards
for the
MAJOR INORGANIC
PRODUCTS
Segment of the
Inorganic Chemicals Manufacturing
Point Source Category
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
AUGUST 1973
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Publication Notice
This is a development document for proposed effluent limitations
guidelines and new source performance standards. As such, this report
is subject to changes resulting from comments received during the period
of public comments of the proposed regulations. This document in its
final form will be published at the time the regulations for this
industry are promulgated.
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DEVELOPMENT DOCUMENT
for
PROPOSED EFFLUENT LIMITATIONS GUIDELINES
and
NEW SOURCE PERFORMANCE STANDARDS
for the-
MAJOR INORGANIC PRODUCTS SEGMENT OF THE
INORGANIC CHEMICALS MANUFACTURING
POINT SOURCE CATEGORY
Russel Train
Administrator
Robert L. Sansom
Assistant Administrator for Air & Water Programs
Allen Cywin
Director, Effluent Guidelines Division
Elwood E. Martin
Project Officer
September, 1973
Effluent Guidelines Division
Office of Air and Water Programs
U.S. Environmental Protection Agency
Washington, D. C. 20460
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ABSTRACT
This document presents the findings of an extensive study of selected
major inorganic chemicals for the purpose of developing effluent
limitation guidelines for existing point sources and standards of
performance and pretreatment standards for new sources, to implement
Sections 304, 306 and 307 of the Federal Water Pollution Control Act, as
amended (33 U.S.C. 1551, 1314, and 1316, 86 Stat. 816 et. seg.)(the
"Act") .
Effluent limitations guidelines contained herein set forth the degree of
effluent reduction attainable through the application of the best
practicable control technology currently available (BPCTCA) and the
degree of effluent reduction attainable through the application of the
best available technology economically achievable (BATEA) which must be
achieved by existing point sources by July 1, 1977 and July 1, 1983
respectively. The standards of performance and pretreatment standards
for new sources contained herein set forth the degree of effluent
reduction which is achievable through the application of the best
available demonstrated control technology, processes, operating methods,
or other alternatives.
Based on the application of best practicable technology currently
available m of the 25 chemicals under study can be manufactured with no
discharge of process waste water pollutants to navigable waters. With
the best available technology economically achievable 23 of the 25
chemicals can be manufactured with no discharge of process waste water
pollutants to navigable waters. No discharge of process waste water
pollutants to navigable waters is achievable as a new source performance
standard for all chemicals except titanium dioxide.
Supporting data and rationale for development of the proposed effluent
limitations guidelines and standards of performance are contained in
this report.
iii.
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CONTENTS
Section Page
I CONCLUSIONS 1
II RECOMMENDATIONS 3
III INTRODUCTION 7
IV INDUSTRY CATEGORIZATION 31
V WATER USE AND WASTE CHARACTERIZATION 75
VI SELECTION OF POLLUTION PARAMETERS 215
VII CONTROL AND TREATMENT TECHNOLOGY 221
VIII COST, ENERGY AND NON-WATER QUALITY
ASPECTS
IX EFFLUENT REDUCTION ATTAINABLE THROUGH
THE APPLICATION OF THE BEST PRACTICABLE
.CONTROL TECHNOLOGY CURRENTLY AVAILABLE,
EFFLUENT GUIDELINES AND LIMITATIONS 353
X EFFLUENT REDUCTION ATTAINABLE THROUGH
THE APPLICATION OF THE BEST AVAILABLE
TECHNOLOGY ECONOMICALLY ACHIEVABLE
EFFLUENT GUIDELINES AND LIMITATIONS 369
XI NEW SOURCE PERFORMANCE STANDARDS AND
PRETREATMENT RECOMMENDATIONS 377
XII ACKNOWLEDGEMENTS 381
XIII REFERENCES 385
XIV GLOSSARY 391
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LIST OF FIGURES
Figure Pane
1 Industry Categorization of Inorganic Chemicals
Manufacturing 34
2 Standard Aluminum Chloride Flow Diagram - 35
3 Standard Process Diagram for Aluminum Sulfate
Manufacturing 37
4 Standard Calcium Carbide Flow Diagram 38
5 Standard Hydrofluoric Acid Flow Diagram 39
6 Standard Calcium Oxide (lime) Flow Diagram 41
7 Standard Hydrochloric Acid Flow Diagram
(Synthetic Process) 42
8 Standard Process Diagram for Nitric Acid 43
9 Commercial Extraction of Potassium 45
10 Standard Process Flow Diagram for Potassium
Dichromate 46
11 General Process Potassium Sulfate Flow Diagra 47
12 Standard Process Diagram for Sodium Bicarbon-
ate 48
13 Process Diagram for Sodium Chloride (Solar
Evaporation Process) 50
14 Standard Liquid Sodium Silicate Flow Diagram 51
15 Standard Anhydrous Sodium Metasilicate Flow
Diagram 52
16 Sulfuric Acid Plant Double Absorption 54
17 Sulfuric Acid Plant Single Absorption 55
18 Standard Process Diagram for Sodium Metal 56
19 Standard Process Diagram for Sodium Sulfite 58
vr
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LIST OF FIGURES
Figure Page
20 Standard Hydrogen Peroxide. Flow Diagram (Riedl-
pfleiderer Process) 59
21 Standard Process for Calcium Chloride Manu-
facture 60
22 Standard Process for Sodium Chcride Manufac-
ture 62
23 Solvay Process Sodium Carbonate Flow Diagram 63
24 Standard Chlorine-Caustic Flow Diagram Diaphragm
Cell Process 65
25 Standard Chlorine-Caustic Flow Diagram-Mercury
Cell Process 66
26 Electrolytic Process for Hydrogen Peroxide 68
27 Standard Sodium Dichromate Process Diagram 70
28 Standard Process Diagram for Titanivim Dioxide 71
29 Flow Diagram of Existing Commercial Chloride
Piocess plants (Titanium Dioxide) 72
30 Aluminum Chloride Waste Treatment 79
31 Aluminum Sulfate Process and Treatment Flow
Diagram of Plant 063 81
32 Aluminum Sulfate Process and Flow Diagram of
Plant 049 " 83
33 Calcium Carbide Process Flow Diagram at Plant
190 85
34 Water Usage at Calcium Carbide Plant 190 86
35 Start-up Treatment System at Plant 121 89
36 Hydrofluoric Acid Process Flow Diagram at
Plant 152 94
VI1
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LIST OF FIGURES
Figure Page
37 Effluent Recycle System at Plant 152 95
38 Flow Diagram for Lime Plant 100
39 Nitric Acid Process Flow Diagram at Plant 114 101
40 Potassium Sulfate Process Diagram at Plant 118 '107
41 Sodium Bicarbonate Process Flow Diagram at
Plant 166 110
42 Sodium Silicate Manufacture at Plant 072 116
43 Double Absorption Contact Sulfuric Acie Process
Flow at Plant 086 118
44 Flow Diagram at Calcium Chloride Plant 185 123
45 Hydrogen Peroxide Process Diagram for Plant 069 126
46 Waste Treatment on Downs Cell Plant 096 130
47 Sodium Sulfite Process Flow at Plant 168 138
48 Solvay Soda Ash Process Flow Diagram at Plant
166 143
49 Calcium Chloride Recovery Process at Plant 166 149
50 Mercury Cell Flow Diagram (Potassium Hydroxide)
at Plant 130 152
51 Histogram of Mercury Discharges from Plant 144 156
52 Mercury Abatement System at Plant 130 157
53 Diaphragm Cell Chlor-Alkali Process at Plant 057 164
54 Sodium Hydroxide Concentration Facility at
Plant 057 165
55 Schematic Showing Waste Sources and Discharge
at Plant 100 171
56 Chromate Manufacturing Facility at Plant 184 177
viii
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LIST OF FIGURES
Figure page
57 Sulfate Process Flow Diagram at Plant 322 187
58 Titanium Dioxide Portion of Titanium
Tetrachloride 192
59 Titanium Tetrachloride Portion of Plant
(Chloride Process) 193
60 Treatment, Titanium Dioxide of Plant. 009 195
61 Treatment, Titanium Tetrachloride of Plant
009 196
62 Time Variation of Effluent Chloride Ion
Concentration at Plant 030 205
63 Frequency Distribution of Effluent Chloride
Ion CcncentratJor at Plant 030 205
64 Time Variation of Effluent tfereur.y Concen-
tration at Plant 144 206
65 Eteqvency Distribution of Effluent Mercury
Concentration at Plant 144 206
66 Time Variation of Effluent Mercury Daily Dis-
charge at Plant 144 207
67 Frequency Distribution of Effluent Mercury
Daily Discharge at Plant 144 207
68 Time Variation of Effluent Chloride Ion
Concentration at Plant 144 208
69 Frequency Distribution of Effluent Chloride
Ion Concentration at Plant 144 208
70 Time Variation of Effluent Chloride Ion
Daily Discharge at Plant 144 209
71 Frequency Distribution of Effluent Chloride
Ion Daily Discharge at Plant 144 209
IX
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LIST OF FIGURES
Figure Page
72 Time Variation of Effluent pH at Plant 144 210
73 Frequency Distribution of Effluent pH at
Plant 144 210
74 Model for Water Treatment and Control System-
Inorganic Chemicals Industry 270
75 Model for Water Treatment System-Inorganic
Chemicals Industry 271
76 Capital Costs for Small Unlined Ponds 315
77 Capital Costs for Large Unlined Ponds 315
78 Construction Costs of Small Unlined Ponds 318
79 Capital Costs for Large Lined Ponds 318
80 Installed Capital Cost for Carbon Absorption
Equipment 319
81 Overall Costs for Carbon Absorption
Equipment 319
82 Installed Capital Cost vs. Capacity for
Demineralization 321
83 Chemical Costs for Demineralization 321
84 Installed Capital Costs for Reverse Osmosis
Equipment 325
85 Costs for Reverse Osmosis Treatment 325
86 Trade-Off Between Membrane Permeability
(Flux) and Selectivity (Rejection and Product
Water Quality) for Cellulose Acetate Base
Membrances 326
87 Energy Comparison for Dissolved Solids
Removal 331
-88 Installed Capital Costs vs. Capacity for
High Efficiency VTE or Multi-Stage Flash
Evaporators 334
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LIST OF FIGURES
Figure Page
89 Overall and Total Operating Costs for VTE and
Multi-Flash Evaporators. 334
90 Capital Cost vs. Effects for Conventional
Multi-effect Evaporators 335
91 Steam Usage vs. Effects for Conventional
Multi-effect Evaporators 336
92 Correlations of Equipment Cost—With Evaporator
Heating Surface 337
93 Overall Costs for 6-Effect Evaporator Treat-
ment of Wastewater 337
94 Disposal Costs for Sanitary Land Fills 343
95 Treatment Applicability to Dissolved Solids
Range in Waste Streams 349
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LIST OF TABLES
Table Page
1 Effluent Limitation Guidelines 4
2 U.S. Production of Inorganic Chemicals
(Metric Tons) 29
3 Plant Effluent from Calcium Carbide
Manufacturing 87
4 Intake Water and Raw Waste Composition
Date at Plant 152 97
5 Comparison of Plant Intake Water to Cooling
Water Discharge at Plant 152 98
6 Plant 166 Verification Data 113
7 Chemical Analysis of Bittern 114
8 intake and Effluent Measurements at Plant
086 120
9 In-Plant Water Streams at Plant 141 122
10 Plant 185 Water Flows 125
10A Composition of Intake & Effluent Streams
of Plant 185 125
11 Plant 069 Process Water Effluent After Treat-
ment 129
12 Plant 096 Effluent 132
13 Plant 096 Effluent 133
14 GTC Verification Measurements at Plant 030 137
15 Measurements of Plant 168 Process Waste
Streams Before and After Treatment 140
16 Plant 168 Cooling Water Measurements 141
17 Calcium Chloride Recovery Process 147
18 GTC Verification Measurements at Plant 166 148
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LIST OF TABLES
Table Page
19 Raw Waste Load from Mercury Cell Process 151
20 Monthly Mercury Abatement System Discharge
During 1972 at Plant 130 155
21 Plant 130 Effluent Data ' 159
22 GTC Measurements of Effluent from Plant 130 160
23 Plant 144 Intake Water 161
24 Plant 144 Effluent Data 162
25 Raw Waste Loads at Plant 100 170
26 Effluent Treatment Data for Plant 100 173
27 Composition of Plant 100 Effluent Streams
after Treatment 174
28 Plant 100 Water Intake and Final Effluent
Verification Measurements 175
29 Intake and Effluent Composition at Plant
184 180
30 Analysis of River Water at the Exemplary
Chromate Facility 184 181
31 Analysis of Waste Treatment Streams at Plant
184 182
32 Sulfate Process Waste Streams—Titanium
Dioxide Manufacture 184
33 Typical Ore Analysis - Titanium Dioxide
Manufacture 185
34 Future Treatment at Plant 122 189
35 Partial Discharge Data from Titanium
Dioxide Sulfate Plants 190
36 Composition of Plant 009 Effluent Streams
After Treatment 197
Xlll
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LIST OF TABLES
Table Page
37 Verification Data of Plant 009 198
38 Summary of BPCTCA and BATEA 225
39 Typical Water-Borne Loads for Inorganic
Chemicals of this Study 243
40 Raw Water and Anticipated Analysis After
Treatment 251-252
41 Water Quality Produced by Various Ion
Exchange Systems 254
42 Special Ion Exchange Systems 256-257
43 Summary of Cost and Energy Information for
Attainment of Zero Discharge 266-267
44 Aluminum Chloride-Treatment Costs 273
45 Aluminum Sulfate-Treatment Costs 274
46 Calcium Carbide-Treatment Costs 276
47 Hydrochloric Acid-Treatment Costs 277
48 Hydrofluoric Acid-Treatment Costs 278
49 Lime-Air Pollution Costs Only 280
50 Potassium Chromate-Treatment Costs 282
51 Potassium Sulfate-TReatment Costs 283
52 Sodium Bicarbonate-Treatment Costs 284
53 Solor Salt-Treatment Costs 285
54 Sodium Silicate-Treatment Costs 287
55 Sulfuric Acid (Sulfur Burning)-Treatment Costs 289
56 Sulfuric Acid (Regen Plant)-Treatment Costs 290
57 Hydrogen Peroxide (Organic Process)-Treatment
Costs 291
58 Sodium Metal-Treatment Costs 293
xiv
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LIST OF TABLES
Table Page
59 Sodium Sulfite-Treatment Costs 294
60 Calcium Chloride Treatment Costs 295
61 Sodium Chloride (Brine Mining)-Treatment Costs 297
62 Soda Ash - Treatment Costs 299
63 Mercury-Cell, Chlor-Alkali-Treatment Costs 300
64 Daphragm Cell, Chlor-Alkali-Treatment Costs 302
65 Hydrogen Peroxide-Electrolytic-Treatment Costs 303
66 Sodium Bichromate-Treatment Costs 304
67 Titanium Dioxide (Chloride Process)-Treatment
Costs 306
68 Titanium Dioxide (Sulfate Process)-Treatment
Costs 308
69 Titanium Dioxide (Sulfate Process) Acid Recovery
Option-Treatment Costs 309
70 Isolation and Containment Costs 311
71 Comparison of Chemicals for Waste Neutralization 313
72 Capital Costs for Lined Solor Evaporation Ponds
as a Function of Capacity 317
73 Costs for Solor Evaporative Pond Disposal 317
74 Overall Costs for Demineralization 323
75 Overall Costs for Demineralization 324
76 Reverse Osmosis-Membrane Replacement Costs 328
77 Reverse Osmosis-Operating Costs 328
78 Evaporator Characteristics 330
79 Cost Estimates for Different Treatments 350
80 Model Treatment Plant Calculations Design
and Costs Basis 351
xv
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SECTION I
CONCLUSIONS
For the purpose of establishing effluent limitation guidelines and
standards of performance, the major inorganic chemicals segment of the
inorganic chemicals manufacturing point source category was initially
divided into subcategories based on compositions of the treated process
waste water from exemplary plants with respect to two important
parameters common in the industry: total suspended solids (TSS) and
dissolved metals. This method of categorization reflects differences in
the nature of raw wastes generated in the manufacture of different
chemicals as well as its treatability. Three categories generally
accommodated the twenty-five chemicals of this- study. Factors such as
plant age, plant size and geographical location did not justify further
segmentation of the industry.
Based on best practicable technology economically achievable, 14 of the
25 chemicals under study can be manufactured with no discharge of
pollutants in process waste water. With the use of best available
technology economically achievable, 23 of the 25 chemicals can be
manufactured with no discharge of process waste water pollutants . to
navigable waters. No discharge of process waste water pollutants to
navigable waters is also achievable as a new source performance
standard.
This study included 25 of the major inorganic chemicals of SIC
categories 2812, 2816, and 2819 which discharge significant quantities
of process waste water containing pollutants into the navigable waters
of the United States. Phase II includes certain other inorganic
chemicals and industrial gases whose annual U.S. production volume
exceeds 450 metric tons (1,000,000 pounds) with similarly significant
waste discharge potential.
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SECTION II
RECOMMENDATIONS
No discharge of process waste water pollutants to navigable waters is
recommended as the effluent limitation guidelines based on best
practicable technology currently available and best available technology
economically achievable and the new source performance standard for the
following chemicals/processes in Category I:
Aluminum Chloride
Aluminum Sulfate
Calcium Carbide
Hydrochloric Acid (Chlorine-Burning)
Hydrofluoric Acid
Calcium Oxide and Calcium Hydroxide (Lime)
Nitric Acid
Potassium (Metal)
Potassium Chromates
Potassium Sulfate
Sodium Bicarbonate
Sodium Chloride (Solar)
Sodium Silicate
Sulfuric Acid
The effluent limitation guidelines based on best practicable technology
currently available for the remaining chemicals/processes in categories
2 and 3 are shown in Table 1.
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TABLE 1. EFFLUENT LIMITATIONS GUIDELINES
Category 2
TSS Concentration = 25 mg/1 (a)
No Harmful Metals Present
Category 3
TSS Concentration = 25 mg/1 (a)
Harmful Metals Present
Chemical Process
Hydrogen Peroxide
(Organic)
Sodium (Metal)
Sodium Sulfite
*- Calcium Chloride
Sodium Chloride
Isoda Ash
Flow (b)
liters/kkg
16,000
9,000
630
330
6,400
6,900
Limitation
kg/kkg
TSS
0.40
0.23
Other
0.22 TOC
0.016 COD 1.7 (d)
(As Cr207)
0.0082
0.15
0.17
Chemical Process
Chlor-Alkali (c)
(Mercury Cell)
Chlor-Alkali
(Diaphragm Cell)
Hydrogen Peroxide
(Electrolytic)
Sodium Dichromate
Flow (b) Limitation
liters/kkg
kg/kkg
TSS
Other
21,000
3,300
95
8,900
0.32
0.083
0.0025
0.22
0.00007 Hg
0.0025 Pb
0.0002 CN.
0.0002 Me
0.0009 Cr-
Sodium Sulfate (See Sodium Dichromate
Titanium Dioxide 90,500 2.2
(Chloride Process)
Titanium Dioxide
(Sulfate Process)
100,000
2.5
(a)
(b)
(c)
(d)
(e)
0.0044 Cr(Total)
by-product)
0.036 Fe
0.014 Pb
0.015 Total
Other Metals
e.g. V, Al, Si,
Cr, Mn, Nb & Zr
0.1 Max. Each
Si02,Co),
Cr203,A1203 .& Fe203
2.0 MnO Max.
3.2 V205
Monthly average values. To convert-from metric units to English Units (Ibs/ton), multiply the above values by 2.
The flow basis numbers are to show how numbers were derived and are not intended as flow limitations.
Because three exemplary plants reduce the concentration of suspended solids to less than 15 mg/1, this process
is an exception to the 25 mg/1 concentration limitation.
COD of 2720 mg of dichromate ion per liter.
"Metals" are total dissolved iron and platinum.
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The daily maximum values are twice the monthly average values unless
otherwise specified. All process water effluents are limited to the pH
range of 6.0 to 9.0.
No discharge of process waste water pollutants to navigable waters is
recommended as the effluent limitation guidelines based on best
available technology economically achievable and new source performance
standard for all the chemicals in categories 2 and 3 except soda ash and
titanium dioxide.
The effluent limitation guidelines based on best available technology
economically achievable soda ash and titanium dioxide are as follows:
Chemical Process
Limitation
TSS
____
Other
2
3
Soda Ash
Titanium dioxide
(Chloride Process)
0.10
1.3
Titanium dioxide
(Sulfate Process)
0.036 Fe
0.014 Pb
0.015 Total
other metals
1.5 0.1 Max. Each
SiO2, CoO,
Cr2O3, A12O3
& Fe203
2.0 MnO Max.
3.2 V205
The new source performance standard for titanium dioxide is the same as
the limitations presented above based on best available technology
economically achievable. New source soda ash plants are required to
achieve no discharge of process waste water pollutants to navigable
waters. <•
The recommendations for treatment of cooling water and blowdowns
represent the degree of effluent reduction attainable by existing point
sources through the application of the best practicable control
technology currently available and the best available technology
economically achievable. They also represent, for new sources, a
standard of performance providing for the control of the discharge of
pollutants which reflects the greatest degree of effluent reduction
achievable through the application of the best available demonstrated
control technology, processes, operating methods or other alternatives
(BAD
The technologies, on which such limitations and standards are based, are
discussed in detail in Section VII of this document.
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Recommendations based on best practicable technology economically
achievable
An allowed discharge of all non^contact cooling waters provided that the
following conditions are met:
(1) No harmful pollutants should be added. Cooling waters discharged
should not have levels of chromate, algicides, fungicides or
other harmful pollutants higher than that of the intake water
or receiving water, whichever is lower,
(2) Thermal pollution should be in accordance with standards to be
set by EPA policy. Excessive thermal rise in once-through
non-contact cooling water in the inorganic chemicals industry
has not been and is not expected to be a significant problem.
(3) All non-contact cooling waters should be monitored to detect
leaks from the process and provisions should be made for
emergency treatment prior to release.
(4) No untreated process waters should be added to the cooling waters
prior to discharge.
An allowed discharge of water treatment, cooling tower and boiler
blowdowns provided these do not contain harmful materials such as
chromium or cadmium and are within the required pH range.
Recommendations based on BATEA and BADT are: The same as those presented
above except that monitoring shall be required for process leaks and
provisions made for emergency holding facilities for cooling water
contaminated by leaks until such time as they can be treated.
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SECTION III
INTRODUCTION
PURPOSE AND AUTHORITY
The United States Environmental Protection Agency (EPA) is charged under
the Federal Water Pollution Control Act Amendments of 1972 with
establishing effluent limitations which must be achieved by point
sources of discharge into the navigable water of the United States.
Section 301(b) of the Act requires the achievement by not later than
July 1, 1977, of effluent limitations for point sources, other than
publicly owned treatment works, which are based on the application of
the best practicable control technology currently available as defined
by the Administrator pursuant to Section 304 (b) of the Act. Section
301(b) also requires the achievement by not later than July 1, 1983, of
effluent limitations for point sources, other than publicly owned
treatment works, which are based on the application of the best
available technology economically achievable which will result in
reasonable further progress toward the national goal of eliminating the
discharge of all pollutants, as determined in accordance with
regulations issued by the Administrator pursuant to Section 304(b) to
the Act. Section 306 of the Act requires the achievement by new sources
of a Federal standard of performance providing for the control of the
discharge of pollutants which reflects the greatest degree of effluent
reduction which the Administrator determines to be achievable through
the application of the best available demonstrated control technology,
processes, operating methods, or other alternatives, including, where
practicable, a standard permitting no discharge of pollutants. Section
304(b) of the Act requires the Administrator to publish within one year
of enactment of the Act, regulations providing guidelines for effluent
limitations setting forth the degree of effluent reduction attainable
through the application of the best practicable control technology
currently available and the degree of effluent reduction attainable
through the application of the best control measures and practices
achievable including treatment techniques, process and procedure
innovations, operation methods and other alternatives. The regulations
proposed herein set forth effluent limitations guidelines pursuant to
Section 304(b) of the Act for the inorganic chemicals manufacturing
point source category.
Section 306 of the Act requires the Administrator, within one year after
a category of sources is included in a list published pursuant to
Section 306(b) (1) (A) of the Act, to propose regulations establishing
Federal standards of performances for new sources within such
categories. The Administrator published in the Federal Register of
January 16, 1973 (38 F.R. 1624) , a list of 27 source categories.
Publication of the list constituted announcement of the Administrator's
intention of establishing, under Section 306, standards of performance
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applicable to new sources within the inorganic chemical manufacturing
point source category, which was included within the list published
January 16, 1973.
SUMMARY OF METHODS USED FOR DEVELOPMENT OF EFFLUENT LIMITATION
GUIDELINES AND STANDARDS OF PERFORMANCE
The Environmental Protection Agency has determined that a rigorous
approach including plant surveying and verification testing is necessary
for the promulgation of effluent standards from industrial sources. A
systematic approach to the achievement of the required guidelines and
standards includes the following:
(a) Categorization of the industry and determination of
those industrial categories for which separate
effluent limitations and standards need to be set;
(b) Characterization of the waste loads resulting from
discharges within industrial categories and sub-
categories ;
(c) Identification of the range of control and
treatment technology within each industrial
category and subcategory;
(d) Identification of those plants having the best
practical technology currently available (ex-
emplary plants); and
(e) Generation of supporting verification data for
the best practical technology including actual
sampling of plant effluents by field teams.
The culmination of these activities is the development of the guidelines
and standards based on the best practicable current technology.
This report describes the results obtained from application of the above
approach to the inorganic chemicals industry. Thus, the survey and
testing covered a wide range of processes, products, and types of
wastes. Studies of a total of twenty-five chemicals, listed in terms of
products below, are summarized in this report. A separate report
covering the phosphorus based segment of the phosphorus chemicals
industry was also generated under the same contract.
Selected Inorganic Chemicals
Aluminum Chloride Potassium Sulfate
Aluminum Sulfate Sodium Bicarbonate
Calcium Carbide Sodium Carbonate (Soda Ash)
Calcium Chloride Sodium Chloride
Chlorine Sodium Dichromate
Hydrochloric Acid Sodium Hydroxide
Hydrogen Peroxide Sodium Metal
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Hydrofluoric Acid Sodium Silicate
Calcium Oxide and Calcium Sodium Sulfate
Hydroxide (Lime)
Nitric Acid Sodium Sulfite
Potassium Chromates Sulfuric Acid
Potassium Hydroxide Titanium Dioxide
Potassium Metal
Categorization and Waste Load Characterization
The effluent limitation guidelines and standards of performance proposed
herein were developed in the following manner. The point source
category was first categorized for the purpose of determining whether
separate limitations and standards are appropriate for different
segments within a point source category. Such subcategorization was
based upon raw material used, product produced, manufacturing process
employed, and other factors. The raw waste characteristics for each
subcategory were then identified. This included an analysis of (1) the
source and volume of water used in the process employed and the sources
of waste and waste waters in the plant; and (2) the constituents of all
waste waters including harmful^ constituents and other constituents which
result in degradation of the receiving water. The constituents of waste
waters which should be subject to effluent limitations guidelines and
standards of performance were identified.
The full range of control and treatment technologies existing within
each subcategory was identified. This included an identification of
each control and treatment technology, including both inplant and end-
of-process technologies, which are existent or capable of being designed
for each subcategory. It also included an identification of the amount
of constituents (including thermal) and the characteristics of
pollutants resulting from the application of each of the treatment and
control technologies. The problems, limitations and reliability of each
treatment and control technology were also identified. In addition, the
non-water quality environmental impact, such as the effects of the
application of such technologies upon other pollution problems,
including air, solid waste, noise and radiation were also identified.
The energy requirements of each of the control and treatment
technologies were identified as well as the cost of the application of
such technologies.
Cost information contained in this report was obtained directly from
industry during exemplary plant visits, from engineering firms and
equipment suppliers, and from the literature. The information obtained
from the latter three sources has been used to develop general capital,
operating and overall costs for each treatment and control method.
Costs have been put on a consistent industrial calculation basis of ten
year straight line depreciation plus allowance for interest at six
9
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percent per year (pollution abatement tax free money) and inclusion of
allowance for insurance and taxes for an overall fixed cost amortization
of fifteen percent per year. This generalized cost data plus the
specific information obtained from plant visits was then used for cost
effectiveness estimates in Section VIII and wherever else costs are
mentioned in this report.
The data for identification and analyses were derived from a number of
sources. These sources included EPA research information, published
literature, qualified technical consultation, on-site visits and
interviews at numerous inorganic chemical plants throughout the U.S.,
interviews and meetings with various trade associations, and interviews
and meetings with various regional offices of the EPA. All references
used in developing the guidelines for effluent limitations and standards
of performance for new sources reported herein are included in Section
XIII of this report.
Exemplary plant selection
The following exemplary plant selection criteria were developed and used
for the selection of exemplary plants.
(a) Discharge effluent quantities
Plants with low effluent quantities or the ultimate of no pollutants
discharge were preferred. This minimal discharge may be due to reuse of
water, raw material recovery and recycling, or to use of evaporation.
The significant parameter was minimal waste added to effluent streams
per weight of product manufactured. The amount of wastes considered
here were those added to waters taken into the plant and then
discharged.
(b) Effluent contaminant level
Preferred plants were those with lowest effluent contaminant
concentrations and lowest total quantity of waste discharge per unit of
product.
(c) Water management practices
Use of good management practices such as water re-use, planning and in-
plant water segregation, and the proximity of cooling towers to
operating units where airborne contamination of water can occur were
considered.
(d) Land utilization
The efficiency of land use was considered.
(e) Air pollution and solid waste control
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Exemplary plants must possess overall effective air and solid waste
pollution control where relevant in addition to water pollution control
technology. Care was taken to insure that all plants chosen have
minimal discharges into the environment and that exemplary sites are not
those which are exchanging one form of pollution for another of the same
or greater magnitude.
(f) Effluent treatment methods and their effectiveness
Plants selected shall have in use the best currently available treatment
methods, operating controls, and operational reliability. Treatment
methods considered included basic process modifications which
significantly reduce effluent loads as well as conventional treatment
methods.
(g) Plant facilities
All plants chosen as exemplary had all the facilities normally
associated with the production of the specific chemical (s) in question.
Typical facilities generally were plants which have all their normal
process steps carried out on-site.
Plant management philosophy
Plants were preferred whose management insists upon effective equipment
maintenance and good housekeeping practices. These qualities are best
identified by a high operational factor and plant cleanliness.
(h) Geographic location
Factors which were considered are plants operating in close proximity to
sensitive vegetation or in densely populated areas. Other factors such
as land availability and differences in state and local standards were
also considered.
(i) Raw materials
Differences in raw material purities were given strong consideration in
cases (e.g., Ti02) where the amounts of wastes are strongly influenced
by the purity of raw materials used. Several plants using different
grades of raw materials were considered for those chemicals for which
raw material purity is a determining factor in waste control. Chemicals
where this was found to be of importance are titanium dioxide, aluminum
sulfate, the dichromates, and to a lesser extent chlorine and sodium
chloride.
(j) Diversity of processes
On the basis that all of the above criteria are met, consideration was
given to installations having a multiplicity of manufacturing processes.
JJ.
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However, for sampling purposes, the complex facilities chosen were those
for which the wastes could be clearly traced through the various
treatment steps.
(k) Production
On the basis that other criteria are equal, consideration was given to
the degree of production rate scheduled on water pollution sensitive
equipment.
(1) Product purity
For cases in which purity requirements play a major role in determining
the amounts of wastes to be treated and the degree of water recycling
possible, different product grades were considered for sub-
categorization.
Sampling of Exemplary Plants
The details of how the exemplary plants were sampled and the analytical
techniques employed are fully discussed in Section V, of this report.
GENERAL DESCRIPTION OF THE INDUSTRY
Brief descriptions of each of the twenty-five chemical industries are
presented in subsequent subsections. Process flow sheets for the
industries may be found in Sections IV and V. Production tonnages
reported for 1971 were taken from Current Industrial Reports, Inorganic
Chemicals, U.S. Bureau of Census, Series M28A(71)-1U.(1) These values
are summarized in Table I, at the end of this section. Also included
are production tonnages for years prior and subsequent to 1971, where
available, and the number of plants producing each chemical.
Aluminum Chloride
The anhydrous product is produced by the reaction of gaseous chlorine
with molten aluminum metal (scrap or scrap-pig mixture). The basic
equation is:
2A1 + 3C12-*2A1C13
Chlorine is introduced below the surface of the molten aluminum; the
product sublimes and is collected by condensation. Waste gases are
removed by a scrubber, which in some facilities provide recycling
capability. streams. Annual U.S. production in 1971 totalled 26,399
metric tons (29,100 tons). The major use is as a catalyst in the
petrochemical and synthetic polymer industries.
A solution grade of aluminum chloride is also produced by reacting
hydrated alumina or bauxite ore with hydrochloric acid. The 1971
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production for the 28% solution product was 7,650 metric tons (8,400
tons) .
Aluminum Sulfate
Aluminum sulfate is produced by the reaction of bauxite ore with
concentrated sulfuric acid (60°Be). The general equation of the
reaction is:
A1203 2H20 + 3H2S04-*A12 (SOU) 3 + 5H20
Ground ore and acid are reacted in a digester, from which the products,
aluminum sulfate in solution plus muds and other insoluble materials
from the ore, are fed into a settling tank. The aluminum sulfate
solution is then clarified and filtered to remove any remaining
insolubles. It may be sold as solution or evaporated to yield a solid
product. Annual U.S. production in 1971 was 1,084,080 metric tons
(1,195,000 tons). Aluminum sulfate, or filter alum, is used for water
treatment (flocculation and clarification) and in treatment of paper
mill waste, sewage, and other waste streams.
Calcium Carbide
This chemical is prepared by the reaction of calcium oxide
with carbon (in the form of coke, petroleum coke, or anthracite) at
2000-2200°C (3632-3992°F) in a furnace similar to the familiar arc
furnace. The general equation for the reaction is:
2CaO + UC + Heat -5* 2CaC2 + 02
Calcium carbide is used primarily in the manufacture of acetylene (by
reaction with water). This use and the tonnage production has been
steadily decreasing. Still, most calcium carbide plants are located in
conjunction with acetylene plants. Since the production process is dry,
the only major discharges are those effluents from scrubbing furnace and
kiln offgases. The U.S. production in 1971 was 567,182 metric tons
(625,338 tons) .
Calcium Chloride
Most of the calcium chloride produced is extracted from impure natural
brines, but some of this salt is recovered as a by-product of soda ash
manufacture by the Solvay process. In the manufacture of calcium
chloride from brine, the salts are solution mined and the resulting
brines are first concentrated to remove sodium chloride by precipitation
and then purified by the addition of other materials to precipitate
sodium, potassium, and magnesium salts. The purified calcium chloride
brine is then evaporated to yield a wet solid which is flaked and
calcined to a dry solid product. Extensive recycling of partially
purified brine is used to recover most of the sodium chloride values.
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Manufacture of calcium chloride from Solvay process waste liquors is
similar to the natural brine process except that the stepwise
concentration and purification is unnecessary because no magnesium is
present. Evaporation and calcining procedures are similar to those
above. Significant wastes result from calcium chloride manufacture. A
typical spent brine treatment might include activated sludge processing,
followed by settling in ponds.
In 1971, U.S. production of calcium chloride was 1,101,281 metric tons
(1,213,000 tons). Uses include de-icing of roads, a stabilizer in
pavement and cement, and dust control on roads. Production is
increasing as more uses and markets are found, but potential production
capability is much greater than that presently utilized. Recently,
increased recovery resulting from pollution abatement measures has
tended to cause calcium chloride supply to exceed demand. Plants
recovering this salt from natural brines are located near mixed salt
deposits, such as those in Michigan, West Virginia, and California.
Calcium Oxide (Lime)
Calcium oxide is produced by calcining various types of limestone in a
continuous vertical or rotary kiln. The general equation
for the reaction is: CaCO3 + Heat-*-CaO + CO2
Formerly coal or coke was used as fuel in vertical kilns, but in recent
years large gas-fired kilns have been widely used. After calcination,
the lime is cooled and then packaged as lump lime or crushed and
screened to yield pulverized lime. As the process itself uses no water,
the only wastes result from wet scrubbing of the gaseous kiln effluent
to remove particulates. These wastes are high pH liquors which also
contain suspended solids.
Annual U.S. production of lime is believed to total about 16,000,000
metric tons (17,600,000 tons). Approximately 20 percent of this
production is "captive11 (made and consumed in the same facility) ,
primarily in the sugar, alkali, and steel industries. The remainder
finds a variety of chemical and industrial uses, including use as an
alkali and in hydrated lime manufacture. Principal growth areas appear
to be in basic oxygen steel production and in soil stabilization.
Chlorine
The major chlorine production results from the electrolysis of sodium or
potassium chloride brines, in which caustic soda (NaOH) or caustic
potash (KOH), respectively, are also produced. The general equation for
the electrolysis is (where M can be either Na or K):
dc
3 MCI + 2H2O-+C12 + 2MOH + H2
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From the above equation it can be seen that hydrogen is also a by-
product of brine electrolysis.
Other sources (minor in size) of chlorine include the manufacture of
hydrochloric acid and metallic sodium.
Two types of electrolysis cells are used. "Diaphragm" cells, which are
becoming favored over the "mercury" type, require initial purification
of the brine in order to produce high grade products. The brine is then
concentrated to near saturation and fed to the anolyte where chlorine is
formed at the anode. The brine then flows through the diaphragm to the
catholyte where caustic is formed.
"Mercury" cells utilize mercury flowing along the bottom of a steel
trough as the cathode. A multiple anode is comprised of horizontal
graphite plates. Upon electrolysis the alkali metal forms an amalgam
with the mercury. The amalgam is decomposed external to the cell by the
addition of water which results in the formation of hydrogen.
The chlorine gas from the cells is collected, cooled, dried by contact
with sulfuric acid, and then purified and liquefied for shipment,
utilized on-site, or sold as gaseous chlorine. Much of the unreacted
salt in the brine is recycled. Besides potential caustic and brine
effluents from both processes, some mercury is present in the spent
brine from the mercury cell process. The cost of removing mercury from
the effluent is relatively high, which accounts for the shift back
toward the diaphragm cells. Mercury cells began to be widely used in
the early 1950's and reached a high of almost 30 percent of the total
production in 1968. The U.S. production of chlorine in 1971 totalled
8,482,660 metric tons of gas (9,352,437 tons) and 4,035,489 metric tons
of liquid (4,449,271 tons). At present, about 75 percent of the
production is in diaphragm cells, 20 percent in mercury cells, and 5
percent from other sources. About two-thirds of the production is
utilized in the synthetic organic chemical and plastics industries, and
half of that remaining is utilized in the pulp and paper industry (as a
bleaching agent). Other uses include the inorganic chemicals industry,
municipal water and sewage treatment, and many others. Somewhat over
half of the total production is "captive", primarily to the synthetic
organic chemicals and the pulp and paper industries. In recent years
proximity to markets has been the major factor in chlorine plant lo-
cation, in contrast to the cost of power and salt which previously
dominated plant economics.
Sodium Hydroxide (Caustic Soda)
Sodium hydroxide is produced from electrolysis of sodium chloride brines
as described above under chlorine. Raw materials include mined rock
salt, solar salt, and natural brines. The caustic solution from the
cathode of the electrolysis cell is evaporated to about 50 percent by
15
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weight sodium hydroxide. This may be sold as "standard-grade caustic
liquor", concentrated to 73 percent, or further refined through removal
of chloride and chlorate by various techniques. Refined caustic liquor
may be sold, further concentrated to 73 percent solids, or evaporated to
dryness and the anhydrous sodium hydroxide sold in solid (flake or
powdered) forms. Most of the product is sold in the liquid form.
Caustic soda has many varied uses; mostly as an alkali. It has also
replaced soda ash (sodium carbonate) in many uses, such as in the
aluminum industry and other molten salt processes, and is used to
manufacture soda ash in one plant. In 1971, the U.S. production of
sodium hydroxide was 8,780,946 metric tons (9,681,397 tons) in liquid
form and 493,393 metric tons (543,983 tons) in solid form.
Potassium Hydroxide (Caustic Potash)
Production methods for potassium hydroxide are very similar to those for
sodium hydroxide, except that mined potassium chloride or potash brines
are used as the raw material. The U.S. production of potassium
hydroxide in 1971 was 179,760 metric tons (198,192 tons). Caustic
potash is used as an alkali, particularly when very high purity is
desired or where other factors allow it to compete with sodium hydroxide
(captive production, for instance). Other uses include the manufacture
of potassium salts and organic compounds containing potassium.
*•
Sodium Metal
Sodium metal is manufactured by electrolysis of fused (molten) sodium
chloride at about 600°C (1072°F). The general equation is:
2NaCl + direct current -»2Na + C12
The salt is mixed with alkali fluorides and calcium chloride to
sufficiently lower the melting point, and the charge is then fused in a
"Downs" cell, which is a closed rectangular refractory-lined steel box
with separate anode and cathode compartments separated by an inorganic
diaphragm. The graphite or carbon anode is fed into the bottom of the
cell, and the cathode is iron or copper in an annular form.
Molten sodium formed at the cathode is transported to a collection
vessel, from which the metal is withdrawn from the bottom, filtered, and
packaged in the form of bricks of various sizes. Very pure metal
results from blanketing the cell and other processing equipment with
argon gas to preclude oxygen from the system. Even the less pure
product, because of its reactivity, must be protected from air and water
throughout the production process.
The U.S. production of sodium metal in 1971 was 138,839 metric tons
(153,075 tons). One of its major uses is in the manufacture of
tetraethyl lead and other organometallic compounds. Other uses include
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production of sodium cyanide, sodium peroxide, titanium, and zirconium.
It is also used in liquid form as a nuclear reactor coolant and as a
light, thermally-conductive solid in various applications.
Potassium Metal
Potassium is produced by the reaction of potassium chloride
with sodium vapor:
KCl + Na + Heat —*• K + NaCl
Since it is relatively more reactive than sodium, the reac-
tion between potassium and carbon (plus a tendency to form
explosive carbonyls) precludes the manufacture of potassium
by electrolysis. Since it is more expensive than sodium,
potassium has very limited uses. Major uses include manufac-
ture of organo-potassium compounds and production of NaK
(sodium potassium alloys used in lard modification and as
a nuclear reactor coolant). Total U.S. production in 1972
was about 100 metric tons (110 tons) .
Hydrochloric Acid
There are two major processes used for hydrochloric acid man-
ufacture. The process to be considered in this report is
direct reaction of chlorine with hydrogen, by:
C12 + H2-*2HC1
The second major source of production for hydrochloric acid, as a by-
product of organic chlorination reactions, is the dominant source. This
source was studied under a different program (organic chemicals). By-
product hydrochloric acid is typically of lower purity than that
produced by direct reaction.
In the production of hydrochloric acid by direct reaction, hydrogen and
chlorine gases are reacted in a vertical burner. The product hydrogen
chloride so formed is cooled and then absorbed in water. Exhaust gases
are scrubbed, and acid values are recycled. End products may include
strong acid (36 percent or 22°Be) from the cooler, weak acid (18°Be)
from the absorber column,, a mixture of these (20°Be) , or anhydrous HCl.
The anhydrous acid may be prepared by stripping gaseous HCl from strong
acid. The condensate and column bottoms from this process may then be
recycled back into the hydrochloric acid recovery process.
Approximately 90 percent of the current production is byproduct, and
supply often exceeds demand. Uses include pickling of steel,
chlorination reactions (in place of chlorine), and a variety of uses as
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an acid agent. Total U.S. production in 1971 was 1,904,075 metric tons
(2,099,371 tons) .
Hydrofluoric Acid
Hydrofluoric acid is obtained by reacting the mineral fluorspar (CaF2)
with concentrated sulfuric acid in a furnace. The general reaction for
this process is :
CaF2 + H2SO4 + Heat -*• H2F2 + CaS04
The hydrofluoric acid leaves the furnace as a gas, which is then cooled
and absorbed in water prior to purification. In the purification
system, the crude acid is redistilled and either absorbed in water to
yield aqueous hydrofluoric acid or compressed and bottled for sale as
anhydrous hydrofluoric acid. Final drying of the anhydrous gas is
accomplished with concentrated sulfuric acid. Aqueous acid is normally
shipped as 70,percent acid.
Most U.S. hydrofluoric acid production (probably 75-80 percent) is
captive to the fluorinated organics and plastics industries. Total U.S.
production in 1971 was 199,069 metric tons (219,481 tons), and the
production appears to be increasing fairly rapidly. Fluorinated
organics and plastics comprise the major use industries, and another
major use is in the production of synthetic cryolite and aluminum
fluoride.
The symbol for hydrofluoric acid may be written HF, H2F2, or HxFx.
Most of the acid-grade fluorspar ore is imported. Waste disposal
problems and safety hazards are specialized and severe because of the
reactivity of the material.
.Nitric Acid
This report covers production of nitric acid in concentrations up to 68
percent by weight (azeotropic concentration). More concentrated nitric
acid, including fuming nitric acid, and nitrogen pentoxide will be
included in the Phase II Report.
Nitric acid is produced by catalytic oxidation of ammonia, first to
nitric oxide (NO) , and then to nitrogen dioxide (NO2,) , which is reacted
with water under pressure to form the acid. The overall reaction scheme
is:
cat.
4NH3 + 502 —* 4NO + 6H20
2NO + 02~ —*- 2N02
3NO2 + H20 —•*-2HN03 + NO
In the process, compressed, purified, and preheated air and anhydrous
ammonia are mixed and passed over a platinum rhodium wire-gauze catalyst
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at about 750°C (1382°F). The resultant mixture of nitric oxide and
excess air is introduced, along with additional air, into a stainless
steel absorption tower in which the nitric oxide is oxidized and the
resulting nitrogen dioxide is reacted with water. The bottom of the
tower yields acid at 61 to 65 percent by weight nitric acid. In a well-
designed plant, the only effluent wastes are treatment chemicals added
to cooling water.
Most of the U.S. nitric acid production is utilized in the fertilizer
industry, and the second largest use is in explosives manufacture.
Various uses as an acidic or pickling agent account for much of the
remaining production. Total U.S. production in 1971 was 6,151,112
metric tons (6,742,130 tons).
Sulfuric Acid
Almost all of the sulfuric acid production in this country arises from
catalytic oxidation of sulfur dioxide to sulfur trioxide (SO3) and its
subsequent reaction with water to form the acid. This method is called
the "contact" process, and the general reactions are:
2SO2 -f O2 -» 2SO3
SO3 + H2O-*H2SO4
The source of the sulfur dioxide for acid manufacture varies widely; raw
materials include sulfur, refinery sludges, pyrites (sulfide ores),
spent acid solutions, recovered SO2, and by-product hydrogen sulfide.
The sulfur, iron sulfide, and hydrogen sulfide are burned in air
according to (respectively):
S + O2 -*• SO2
4FeS2 + 11O2 -*• 8SO2 + 2Fe2O3
2H2S + 3
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concentrations; dilute acid requires specialized containers of glass or
lined with glass, rubber, or lead.
Total U.S. production in 1971 was 26,685,916 metric tons (29,422,179
tons). About 60 percent of this production is captive, much of it
supplying the fertilizer, petroleum refining, and explosive industries.
There are many other large-tonnage industrial uses, including the
manufacture of synthetic plastics, detergents, hydrofluoric acid, nu-
clear fuels, and various other organic and inorganic chemical products.
Hydrogen Peroxide
Hydrogen peroxide (H2O2) is manufactured by three very different
processes: (1) An electrolytic process; (2) Oxidation of alkyl
hydroanthraquinones; and (3) As a by-product in the manufacture of
acetone from isopropyl alcohol. This report includes processes (1) and
(2) above; the third process was presumably considered under another
study (organic chemicals) .
In the electrolytic process, a solution of ammonium (or other) bisulfate
is electrolyzed, yielding ammonium persulfate at the anode and hydrogen
gas at the cathode. The persulfate is then reacted with water
(hydrolyzed) to yield hydrogen peroxide and the original bisulfate. The
general reaction scheme is: dc
2NHUHSO4 —*• (NH4) 2S20.8 + E2
(NH4) 2S208 + H20 —»-2NHUHSOO. + H202
The crude peroxide product emerges mixed with water, and can be
concentrated to desired levels by vacuum distillation or low-temperature
fractionation. The cathode liquor is filtered and reused.
The alkylhydroanthraquinone oxidation process is portrayed in general
form below ("R" represents the alkylanthraquinone molecule, except for
the two double-bonded oxygens):
Cat.
O=R=O + H2 —*>HOR-OH
HO-R-OH + O2 —^O=R=O + H202
In this process, the alkylanthraquinone is reduced by hydrogen over a
supported metal catalyst (typically palladium on alumina), the product
being the corresponding alkylhydroanthraquinone. This, in turn, is
oxidized by oxygen in a forced gas stream to reform the original
alkylanthraquinone plus hydrogen peroxide. The hydrogen peroxide is
extracted with water and the alkylanthraquinone is recycled.
Hydrogen peroxide is sold in a range of aqueous concentrations from
three percent to 98 percent by weight. The higher concentration
materials are dangerously reactive. A stabilizer (such as acetanilid)
is typically added to the product to retard decomposition. Uses are
many and various and include bleaching of textiles and paper.
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epoxidation, production of peroxy-acid catalysts, oxidation of organic
compounds, formation of foams, and a source of energy for both military
and civilian applications. The U.S. production in 1971 was 57,937
metric tons (63,878 tons).
Sodium Chloride
Large quantities of this chemical are produced from brine or seawater by
three basic processes. Some rock salt is sold in the purity obtained
from the mine (for uses where impurities are not important).
Pretreatment of the brine before sodium chloride recovery depends on the
impurities present. Brines obtained from dissolution in water pumped
through an underground salt deposit will typically also contain calcium
sulfate, calcium chloride, and magnesium chloride, plus traces of
hydrogen sulfide and iron. These impurities are removed or controlled
by various methods. Sodium sulfate often is another impurity, and it is
removed during salt purification.
In the "Grainer" process, saturated and pretreated brine is heated in a
flat, open pan (or grainer). Flat crystals of sodium chloride form on
the quiescent surface of the solution and fall to the bottom of the
grainer. There they grow until they are removed by a submerged rake
system. Recovered crystals are subsequently washed, dried, classified
as to size, and packed. Brine pretreatment allows sodium chloride
purities of 99.98 percent by this method.
In the "vacuum pan" system, pretreated brine enters vacuum evaporators
which remove water and allow sodium chloride crystals to precipitate
out. The crystals are then washed, filtered, and dried prior to
packing. The "Alberger" process is similar except that an open
evaporator is used to remove water sufficiently to allow precipitation
of salt crystals. These crystals are centrifuged to remove liquid,
dried, and packed. The feed to the open evaporator includes saturated
brine and a slurry of sodium chloride crystals in brine. This slurry is
the liquid effluent from the evaporator with some of the water removed
by evaporation.
A. wide variety of solid products are available, with various particle
sizes, solid forms, purities, and additives. Exact production figures
are not available, but current production appears to be between
40,000,000 and 50,000,000 metric tons (44,000,000 and 55,000,000 tons)
per year. Because salt sources are widespread and the product is
relatively inexpensive, production facilities are localized and operated
on a relatively low profit margin. Major salt deposits in the U.S.
include a large bed extending from western New York through much of
Michigan, brine wells in the Ohio Valley, a large bed under central
Kansas and northern Oklahoma, and salt domes in Texas and Louisiana. In
1971 salt production by solar evaporation was 2,140,000 metric tons
(2,350,000 tons) and the production by solution mining was 5,390,000
metric tons (5,928,000 tons). Practically all chemical compounds
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containing sodium or chlorine are derived from salt. The chemical
industry utilizes almost all of the brine produced and over half of the
rock salt production. About three percent of the production is used as
table salt, although more than this is utilized in the food processing
industry.
Sodium Carbonate
Sodium carbonate, or soda ash, is produced by the "Solvay" (ammonia-
soda) process and by mining of naturally-occuring deposits in California
and Wyoming. Production by mining is less than that from the Solvay
process. In the mining process, trona (sodium sesquicarbonate,
Na£CO3_»NaHC03«2H20) is brought to the surface in solid form, crushed and
ground, and dissolved in water. The solution is clarified, thickened,
filtered, and sent to vacuum crystallizers, from which part of the soda
ash is recovered in solid form. The remaining solution is cooled to
precipitate additional soda ash and bicarbonate. These solids are then
dewatered and calcined to yield soda ash.
The Solvay process involves a reaction in aqueous solution (under
pressure) between ammonia, brine (NaCl), and carbon dioxide to yield
sodium bicarbonate, which is then converted to soda ash by heating.
Ammonia is recovered by the addition of slaked lime to the used liquor.
The general reaction is as follows:
Formation of Ammonium Bicarbonate
NH3 + H2O-*-NHUOH
NH40H + C02-»NH^HC03
Conversion to Sodium Bicarbonate
NHUHC03 + NaCl->NaHC0.3 + NHUCl
Conversion to Soda Ash
2NaHC03 + Heat-*Na2C03 + C02 + H20
Recovery of Ammonia
2.NH4C1 + Ca(OH) 2-*2NH3 + CaC12 + H20
The saturated brine is purified of other metal ions by precipitation,
and then picks up ammonia in an absorber tower. Ammoniated brine is
reacted with carbon dioxide in a carbonating tower, and the resulting
bicarbonate precipitates as the sodium salt, forming a slurry. The
slurry is filtered to remove the solid bicarbonate which is calcined to
yield the light ash product. Dense ash is made by successive hydration
and dehydration of the light ash. The carbon dioxide and ammonia are
recycled. Calcium chloride is also being recovered now in some plants.
Many soda ash plants are associated with producers of glass (largest
user industry) or with sources or raw material such as coke-oven plants
(by-product ammonia), the cement industry (utilization of lime sludge),
or solid carbon dioxide producers. Soda ash competes with caustic soda
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and other chemicals in a variety of applications other than glass
manufacture. Large amounts are used in the non-ferrous metals industry
and in the production of bicarbonate and washing soda. Several types of
products are sold commercially. Production figures for the U.S. in 1971
are as follows:
Finished Light Ash - 1,676,621 metric tons (1,848,535 tons)
Finished Dense Ash - 2,120,467 metric tons (2,337,891 tons)
Natural Ash - 2,598,321 metric tons (2,864,742 tons)
Total - 6,395,409 metric tons (7,051,168 tons)
Sodium Bicarbonate
Sodium bicarbonate, also known as baking soda, is made by the reaction
of sodium carbonate with water and carbon dioxide under pressure. The
bicarbonate so formed precipitates from solution and is filtered,
washed, dried, and packaged. The general process reaction is:
Na2COj! + H20 + C02 -*-2NaHC03
The case of sodium bicarbonate is an example of a process where it is
more economical to purify a raw material (sodium carbonate) to obtain a
pure product then to purify an impure end product (the intermediate
bicarbonate in the Solvay process). Sodium bicarbonate is typically a
minor product of soda ash manufacturers.
Total U.S. production in 1971 was 158,305 metric tons (174,537 tons).
Major industrial users include food processing, chemicals,
Pharmaceuticals, synthetic rubber, leather, paper, and textiles. It is
also used in fire extinguishers to form carbon dioxide and in food
preparation.
Sodium Silicate
Several forms of sodium silicate are manufactured including both liquid
and anhydrous (solid or powder) forms of sodium metasilicate (Na2SiO3_) ,
sodium orthosilicate (Na4siO^) , and sodium tetrasilicate (Na2!Si4O9) .
The liquid forms are generally sold in 20 to 50 percent by weight
aqueous solutions called "water glass" (so-called because they solidify
to a glass which is water-soluble). The general production process
involves reaction of caustic soda (NaOH) and silica (SiO2), with the
relative proportions of the reactants used determining the product
composition. Equations for the several reactions are:
Sodium Metasilicate
4NaOH + 2Si02 + Heat-?-2Na2Si03 + 2H20
Sodium Orthosilicate
4NaOH + Si02 + Heat->Na4Si04 + 2H20
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Sodium Tetrasilicate
2NaOH + 4S1O2 + Heat*Na2Si409 + H20
Sodium silicates other than those listed above can be produced by
further variation of the caustic-silica reactant ratios.
In a typical process, caustic soda and silica sand are mixed in the
desired proportion and charged to a furnace. Water and steam are added
to the product under pressure to completely dissolve the silicate. The
liquid product is then stored or used to produce silicate in solid form.
The production of solid silicate from silicate solution essentially
involves evaporation of the water, although the silicate in solution may
be further reacted with caustic during the process if a higher sodium
crude content is desired in the solid product. This is typically the
case in the production of sodium metasilicate (anhydrous) from
tetrasilicate water glass. The dried anhydrous silicate is screened and
milled to achieve the desired particle sizes.
Silicate plants are relatively simple, and many are captive to soap or
catalyst manufacturers or other users. One of the major uses is in the
manufacture of silica gel. In 1971, the U.S. production of sodium
silicate in water glass form was 569,701 metric tons (628,116 tons), and
that of anhydrous sodium metasilicate 244,808 metric tons (269,910
tons) .
Sodium Sulfate
Sodium sulfate (salt cake) is produced as a by-product from sodium
dichromate manufacture, by direct mining and natural brine recovery
operations, and as a by-product of organic syntheses. Most of the U.S.
production arises from production of rayon and various organic chemicals
and is thus not covered in this report. Production from mining and
natural brines (in southwestern U.S.) is also not considered here, a
major reason being that apparently no effluent wastes result from these
operations.
In sodium dichromate manufacture, soda ash, lime, and chrome ore are
reacted and the products leached with sulfuric acid to convert the
chromate to dichromate. The leachate, containing sodium sulfate in
addition to sodium dichromate, is partially evaporated to the point
where the sulfate is precipitated. The solid sulfate is filtered out,
dried, and sold. The chromate conversion reaction in which the sulfate
is formed is: 2Na2Cr04 + H2S04-*Na2!Cr207 + H20 + Na2S04
Since sodium sulfate is primarily a by-product material, the supply
often exceeds the demand. In addition, the natural product is
relatively abundant and limited in competition only by distance from the
markets. The largest use is in the kraft pulp and paper industry.
Another major use is as a "builder" in detergents. Total U.S.
24
-------
production in 1971 was 764,409 metric tons (842,788 tons) of high purity
sodium sulfate and 465,785 metric tons (513,545 tons) of Glauber's salt
(Na2SO4»10H2O) . The dichromate by-product is sometimes called "chrome
cake". Present production of this form of sodium sulfate is estimated
to be 110,000 metric tons (121,000 tons) per year.
Sodium Sulfite
The most important method of sodium sulfite manufacture consists
essentially of reacting sulfur dioxide with soda ash (Na2CO3_) . Another
source is as a by-product from the production of phenol through the
reaction of sodium benzene sulfonate with sodium hydroxide. The latter
is not considered in this report.
In the soda ash-sulfur dioxide reaction process, the sulfur dioxide gas
is passed into a solution of sodium carbonate until the product is
acidic. At this point the solute consists primarily of sodium bisulfite
(NaHSO3) , which is then converted into sodium sulfite (Na2_SO3) by the
further addition of soda ash and boiling until all the carbon dioxide is
evolved. The overall reaction is: SO2 + Na2C03_-*Na2s03 + C02
Sodium sulfite is a mild reducing agent, and is widely used as an
antioxidant. Specific uses include bleaching and stabilization of
yarns, textiles, and paper, preservation of foodstuffs and photographic
developers, and as a boiler feed water additive. The paper industry is
the largest consumer. Total U.S. production in 1971 was 185,393 metric
tons (204,402 tons) .
Sodium Dichromate
Sodium dichromte (Na2Cr2O7) is prepared by calcination of a mixture of
chrome ore (typically chromite, FeO.Cr2O3_) , sodium carbonate, and lime,
followed by a water leach and conversion of the soluble chromates to
dichromate with sulfuric acid. The overall reaction scheme is:
Formation of Chromate
4(FeO.Cr203) + 8Na2c03 + 702-> 8Na2Cr04 + 2Fe203 + 8C02
Conversion to Dichromate
2Na2Cr04 + H2S04 -*Na2Cr207 + H20 + Na2S04
After the leaching operation, calcium salts are precipitated by pH
adjustment and then removed along with the iron oxide. The leachate
containing the soluble chromate is then acidified by addition of
sulfuric acid, forming the dichromate and sodium sulfate. The sulfate
is removed (see section on sodium sulfate), and the dichromate solution
is partially evaporated and removed to a crystallizer where sodium
dichromate crystals are allowed to form. The crystals are centrifuged
to remove excess water and then dried and packed for shipment.
25
-------
Other chromate products are often made in the same plant, including
production of "chromic acid" (sold as the liquid solution of CrO3) by
treatment of sodium dichromate with sulfuric acid, and sodium chromate,
produced either by the chromite ore reaction above (crude chromate) or
by reaction of sodium dichromate with soda ash (very pure product) .
Sodium dichromate is the major product of the industry. It is sold as
the familiar orange-colored dihydrate (Na2_Cr207_«2H20) . Current
production is estimated to be between 100,000 and 150,000 metric tons
(110,000 and 165,000 tons). The major demand for this chemical is in
the manufacture of pigments. Other uses include leather tanning, metal
treatment, and corrosion inhibition.
Potassium Dichromate
Most of the potassium dichromate manufactured in the U.S. is made by
reacting sodium dichromate dihydrate solution with potassium chloride
according to the following:
Na2Cr207«2H20 + 2KC1-* K2Cr207 + 2NaCl + 2H20
The potassium dichromate is crystallized from the solution and the
sodium chloride is recovered as a solid waste because it is contaminated
with the chromate.
A relatively pure product results which requires only removal of the
water prior to sizing and packaging. The major uses of potassium
dichromate are as a glass pigment and a photographic development
chemical. Estimated current production in the U.S. is 4,000 to 4,500
metric tons (4,400 to 5,000 tons) per year.
Potassium Sulfate
The bulk of the potassium sulfate manufactured in the U.S. is prepared
by the treatment with potassium chloride of dissolved langbeinite, a
naturally-occuring potassiummagnesium sulfate mineral, K2S04«2MgS04_.
Mined langbeinite is crushed and dissolved in water to which potassium
chloride is added. Partial evaporation of the solution results in
selective precipitation of potassium sulfate which is recovered by
centrifugation or filtration, dried, and sold. Magnesium chloride may
be economically recovered as a byproduct, if the raw material is of
sufficiently high quality. 407,916 metric tons (449,742 tons) . Much of
this finds agricultural use, particularly for tobacco and citrus.
Titanium Dioxide
Titanium dioxide is the most widely used white pigment. It is produced
by two methods termed the "sulfate" process and the "chloride" process.
26
-------
In the chloride process titanium dioxide (TiO2) ores are chlorinated to
produce titanium tetrachloride. Coke is included to promote the
reaction. The resulting titanium tetrachloride is oxidized to titanium
dioxide and chlorine (which is recycled), A general reaction scheme
using rutile (Fe2_03_»Ti02) as the raw material is shown below:
Chlorination Reaction
TiO2 • Fe2_O3_ + 2C12_ + C-» TiCl4 + C02_ + FeCl3
Oxidation Reaction
TiClU + O2 -*• TiO2 + 2C12
The Chlorination reaction above is only approximate, because the iron
chloride which results may be a mixture of several chlorides, and some
carbon monoxide is formed. The actual products and product ratios will
depend on the raw material and the reactant ratios used.
Impurities in the system, including the iron and other metal (Al, V,
etc.) chlorides, entrained coke and ore, carbon monoxide and dioxide,
and hydrogen chloride (HCl) all have to be removed prior to the
oxidation reaction, creating a significant effluent waste control
problem. After Chlorination the products are cooled to condense the
undesired metal chlorides. Solids are separated by centrifugation or
filtration, and the gaseous titanium tetrachloride is condensed. A
number of techniques are used to further purify the tetrachloride.
After purification the titanium tetrachloride is vaporized and passed
into a reactor with heated air or oxygen. The solid titanium dioxide
particles are mechanically separated from the gas stream, calcined,
ground, surface-treated, and packed. In the sulfate process, titanium
dioxide-bearing ores are dissolved in sulfuric acid to produce titanium
sulfate as an intermediate product. The acid solution is clarified, a
portion of the iron sulfates is removed by crystallization, and the
titanium sulfate is hydrolyzed to form a white, non-pigmentary hydrate.
The hydrate is calcined to form crystalline titanium dioxide, which is
milled, surface treated, and packaged for sale. Product quality from
the sulfate process is not so dependent on ore quality as is that from
the chloride process.
A general reaction scheme for the sulfate process using ilmenite
containing various iron oxides (FeO and Fe2O3) is presented below:
Acidification
FeO(Fe203) .TiO2 + 5H2SOU -* FeSO4 + Fe2 (SOjt) 3 + TiOSOU + 5H2O
Hydrolysis to Form Hydrate
TiOSOU + 2H2O —*TiO2.H2O + H2SOU
Calcination
TiO£.H2O -i-Heat —> TiO2 + H2O
Various grades, purities, and surface finishes of several crystalline
forms are sold commercially. The pigment is also sold mixed with 50 to
70 percent calcium sulfate. Although the paint industry is the major
user, various types of titanium dioxide are used in paper, inks,
27
-------
fabrics, rubber, and floor coverings. Total U.S. production in 1971 was
614,720 metric tons (677,751 tons). Domestic ore is found in New York
and Florida, plus lesser amounts in North Carolina, Virginia, and Idaho.
The remaining ore supply is imported, much of it from Canada and India.
Most of the production of this pigment is captive to the large paint
manufacturers.
28
-------
TABLE 2. U.S. Production of Inorganic Chemicals (Metric Tons)
1973 (Est.)
MC11
<\12(S04)3
CaC2.
CaC12
C12.(g) 9,
HC1 2,
HF
H2.02.
Lime
HNOJ 6,
K2Cr207
KOH
K
K2S04
Na~HC03
Na£C03, total
"Synthetic 3,
NaCl
NaCl (Solar)
NaCl (Solution
480,031
131 ,873
731 ,276
1
8
1
6
1972
30
,019
447
861
,952
,996
301
68
,369
(Estimated)4
91
991 ,592
Mining)
6
3
Na2Cr207 (& Chromate)
Na"3H 9,
Na
Sodi urn Sili cate
Na2S04
NalSQj
H£S04. 29,
Ti 0,2.
797,544
664,786
644,098
9
1
27
161
,768
,929
124
,196
601
,236
,257
623
,844
,670
,240
,821
,052
,703
,184
,039
,311
,309
,478
,470
,904
,284
,084
,460
,486
,130
,233
1971
26
1 ,084
566
1 ,100
8,483
1 ,904
199
58
6,116
179
407
158
6,396
3,878
2,350
5,928
125
9,276
138
569
1 ,230
185
26,691
615
,399
,080
,988
,409
,947
,171
,126
,060
,208
,622
59
,959
,756
,526
,194
,000
,000
,191
,006
,799
,709
,136
,065
,000
,068
1970
28
1 ,080
717
1 ,006
8,857
1 ,827
203
55
6,059
158
296
129
3,985
139
9,199
155
569
1 ,245
222
26,784
594
,485
,451
,579
,000
,700
,060
,571
,338
,055
,756
285
,285
,727
,242
,706
,712
,128
,709
,558
,259
,489
,203
No. of
Plants
1969 (1971)
35
1 ,136
776
1 ,066
7,801
1 ,733
200
58
15,422
5,844
160
277
124
6,350
4,118
39,008
138
8,996
149
596
1 ,341
205
26,795
602
,834
,696
,546
,843
,748
,621
,940
,967
,060
,960
,570
,143
,284
,260
,597
,740
,798
,504
,685
,017
,719
,930
,375
,367
5
100
7
9
63
83
13
5
97
72
2
13
1
7
5
13
7
85
6
?
6
62
5
33
40
6
150
14
29
-------
SECTION IV
INDUSTRY CATEGORIZATION
For the purpose of establishing effluent limitations guidelines and
standards of performance, the inorganic chemicals industry has been
subcategorized based on the character of wastes in the treated effluent
from exemplary plants. The waste water constituents selected as the
basis for segmentation of the industry are suspended solids and
dissolved metals.
The generation of suspended solids is common to the manufacturing
processes of all chemicals using process water. In general, the level
of suspended solids may be reduced in each process effluent using
similar treatment techniques, including gravity settling, clarification,
flocculation and various filtration operations.
The presence of metals in the process effluent usually necessitates
additional treatment, specific for each manufacturing process. Thus,
separate categories were established for those chemicals whose
manufacture produces a dissolved metal-containing effluent and those
which do not.
The inorganic chemicals industry is so large and diverse, that neither
raw materials nor manufacturing processes provide a workable basis for
categorization of the industry. Water usage is determined by the needs
of individual plants and varies greatly depending on the specific
chemical manufactured.
Factors such as age of plant, size of plant, geographical location,
product purity and waste control technologies do not generally justify
further segmentation of the industry. In some cases, however, a
particular product is manufactured by two different processes which
generate dissimilar waste loads. An example of this is sodium chloride
which is produced by two methods, solar evaporation and brine mining.
These exceptions, however, fit better into the selected categorization
scheme than into any other rationale considered. Similarities in waste
loads within the subcategories and the applicability of available
control and treatment technologies further substantiate this.
CATEGORIZATION CRITERIA
It was determined that the most effective method of categorization was
based on the kilograms of pollutant per metric ton (kg/kkg) of
production in the treated effluent from exemplary plants. The principal
pollutants from the inorganic chemicals industry are suspended solids,
dissolved solids, metals and harmful pollutants.
31
-------
(a) Total suspended solids
The generation of suspended solids is common to all manufacturing
processes. Similar treatment methods to reduce or eliminate suspended
solids are generally employed for all manufacturing process waste
waters. It was found that the treated effluent from exemplary plants
contained no suspended solids for 14 of the 25 chemicals studied.
(b) Total dissolved solids
Total dissolved solids content is the singular major pollutant of the
inorganic chemical industry. However, it does not serve as a workable
categorization basis. The concentrations of dissolved solids in treated
effluents from exemplary plants vary significantly depending on the
chemical produced and the source of intake water.
(c) Metals and harmful pollutants
Chemical processes were grouped by the presence or absence of metals and
other harmful pollutants in the treated effluent from exemplary plants.
Although these waste water constituents are generally present in small
quantities, they were selected as a basis for categorization because
additional control and treatment techniques are required to reduce
concentrations to acceptable levels.
Industry categories
Utilizing the treatment scheme summarized above, all chemicals studied
may be grouped into three categories. The chemicals contained in
Category 1 are those which may be practicably manufactured, yielding a
zero discharge of pollutants in the process waste water. They include:
A1C13 K2Cr207
A12 (SO4)3 K2SO4
CaC ~ NaHCO3
HC1 Nad (solar)
Lime NaSiO3
HNO3 H2SOU~
K HF .
The chemicals grouped in Category 2 are characterized by an effluent
having no dissolved metals present. Suspended solids are present and
may be practicably reduced to a concentration of 25 mg/1 using currently
available technologies. Each manufacturing process in this category is
unique for the specific chemical produced, however. As such, each
chemical has individual water requirements and the resulting absolute
quantity of suspended solids discharged per weight of product produced
is variable, depending on the chemical manufactured. The chemicals in
Category 2 are:
32
-------
H2_02_ (organic)
Na
Na2SO3
CaCl
NaCl (brine mining)
Soda Ash
Category 3 chemicals have a treated effluent containing dissolved metals
and having a suspended solids concentration of 25 mg/1. Again, specific
water uses vary from chemical to chemical, yielding dissimilar absolute
quantities of suspended solids based on production volume. The type of
dissolved metals present obviously depend on the specific chemical manu-
facturing process. The chemicals in Category 3 include:
Chlor-Alkali* (Mercury Cell)
Chlor-Alkali (Diaphragm Cell)
H2O2 (Electrolytic)
Na2Cr2O7
Na2SO4
TiO2_ (Chloride)
Ti02 (Sulfide)
*Because three exemplary plants reduce the concentration of suspended
solids to less than 15 mg/1, this process is an exception to the 25 mg/1
concentration encountered with the other chemicals.
A chart showing where the individual chemical processes fall with
respect to these three categories is shown in Figure 1.
SPECIFIC INDUSTRY DESCRIPTION BY CATEGORY
Category 1 chemicals
The inorganic chemicals studied were divided into three basic categories
consistent with -the waste characteristics of treated effluents from
exemplary plants. The process and raw materials used for each of the
chemicals in Category 1 are discussed below.
Aluminum chloride (anhydrous)
Aluminum chloride is made by reaction of chlorine with molten aluminum.
The aluminum chloride formed vaporizes and is collected on air cooled
condensers. .The tail gases leaving the condensers are the only source
of wastes. A standard process diagram is shown in Figure 2.
There are three types of products manufactured, all from the same
general process:
(1) Yellow - this product is made using a slight excess
of chloride (0.0005%) and may contain some ir.on due
to reaction of the chloride with the vessel;
(2) White - this product has a stoichoimetric aluminum and
chlorine starting ratio; and
33
-------
10,000
1,000
100
3
o
CO
10
$
CO
AICI3
ALUM
CflC2
LIME
OSODA
ASH
CHLORIDE
Ti02 SULFATE
Clg DIAPHRAGM
NdgSC^O
CELL
ONaC> BRINE MINING
ELECTROLYTIC
NflHC03
NdCI(SOLAR)
0.1
0.001 0.01 O.I I tO
TOTAL SUSPENDED SOLIDS (lb/ton)A
100
LEGEND:
O METALS AND HARMFUL IONS ABSENT (CATEGORY 2)
% METALS OR HARMFUL (ONS PRESENT (CATEGORY 3)
A kfl/kkfl = tb/ton ••• 2
FIGURE I
INDUSTRY CATEGORIZATION OF
INORGANIC CHEMICALS MANUFACTURING
-------
CHLORINE
ALUMINUM
>>
1^
s
REACTOR
\
X.
^
CONDENSER
' N
f
PAI
(NaOH)
WATER
,1
VENT
/N
WASTE
GASES
(CI2+
PARTICULATE
AlClj)
WASTE
(DROSS, SOUD)
AICI3
PRODUCT
SCRUBBER
V
WASTE
AI(OH)3
(NaCI)
(NaOCI)
HCI
FIGURE 2
STANDARD
ALUMINUM CHLORIDE FLOW DIAGRAM
-------
(3) Grey - this product contains 0.01% excess aluminum.
The unreacted aluminum raw waste load is higher for
this gray material.
In most cases it makes little difference which of the above grades is
employed. In some pigment and dye intermediate applications, the yellow
material is preferred because it is free of elemental aluminum.
Aluminum chloride is also made from the reaction of bauxite, coke and
chlorine. About 80 percent of all aluminum chloride made is anhydrous.
A solution grade of aluminum chloride is also produced by reacting
hydrated aluminum or bauxite ore with hydrochloric acid.
Aluminum sulfate
Aluminum sulfate is prepared by reaction of bauxite ore with sulfuric
acid. The ore and sulfuric acid are reacted in a digester and the
resulting aluminum sulfate solution, containing muds and other
insolubles from the ore, is then fed to a settling tank, where the
insolubles are removed by settling and filtration. The filtered product
liquor is then either shipped as liquid aluminum sulfate solution or
evaporated to recover a solid product. A typical diagram is shown in
Figure 3.
Calcium carbide
Calcium carbide is manufactured by the thermal reaction of lime and coke
as is shown in Figure H. Lime and dried coke are reacted in a furnace
and the product is then cooled, crushed, screened, packaged and shipped.
The only wastes from the process are air-borne dusts from the furnace
coke dryer and screening and packing station. Currently, dust from the
coke dryer is collected in bag filters. Bag filters are also now being
used on the furnace and the packing areas. All collections are returned
to the furnace.
Hydrofluoric acid
Hydrofluoric acid is manufactured by reaction of sulfuric acid with
fluorspar ore (mainly calcium fluoride). The reaction mixture is heated
and the hydrofluoric acid leaves the furnace as a gas, which is cooled,
condensed and sent on to a purification unit. There the crude
hydrofluoric acid is redistilled and either absorbed in water to yield
aqueous hydrofluoric acid or compressed and bottled for resale as
anhydrous hydrofluoric acid. A general process flow diagram is shown in
Figure 5.
Calcium Oxide and Hydroxide
Calcium oxide and calcium hydroxide is manufactured by the
thermal decomposition of limestone in a kiln. The limestone is first
36
-------
SULFURIC
ACID
WASHOUT <
WASTES
(MUDS, Al (S04L,
H2S04)
WASTE
(MUDS)
WASTE <-
(MUDS)
BAUXITE
ORE
DIGESTER
V
SETTLING
TANK
V
FILTRATION
EVAPORATION
SOLID
ALUMINUM
SULFATE
PRODUCT
I
STEAM
STORAGE
LIQUID
ALUMINUM
SULFATE
PRODUCT
FIGURE 3
STANDARD PROCESS DIAGRAM FOR
ALUMINUM SULFATE MANUFACTURE
37
-------
COKE
u>
00
COAL
LIMESTONE-
CRUSHING
I HOT AIR-
I
I
AIR-SWEPT
PULVERIZING
DRYING
CRUSHING
KILN
GAS VENT
WATER SPRAY
\\\\\
COOLER
T
AIR
1
GAS
SCRUBBER
CARBIDE
FURNACE
COOLING
CRUSHING
FIGURE 4
STANDARD
CALCIUM CARBIDE FLOW DIAGRAM
STORAGE
V
WASTE
-------
OLEUM
MIXER
r
REACTOR
WASTE
HF
COOLER
i
\/
-L
DRIP POT
V
COKE BOX
CRUDE HF STORAGE
v
rTERt
TO
WASTE
ACID STORAGE
EJECTOR
4,
WASTE
FIGURE 5
HYDROFLUORIC ACID FLOW DIAGRAM
39
-------
crushed then added to the kiln, wherein it is calcined to effect
decomposition. The product is then removed from the kilns,
marketed as calcium oxide (quicklime) or slaked by reaction with water
to calcium hydroxide and then marketed. A process flow chart is given
in Figure 6.
Hydrochloric acid
Hydrochloric acid is manufactured principally by two processes: (1) as a
by-product of organic chlorinations and (2) by direct reaction of
chlorine with hydrogen. The by-product acid is being studied under the
organic chemicals program and the direct burning process falls within
the scope of this program. Hydrochloric acid is also manufactured by
the Salt or Mannheim Process involving the reaction of sulfuric acid and
salt and by the Hargreaves Process in one plant involving the reaction
of salt, sulfur dioxide, air and water. Both these processes produce
sodium sulfate as a by-product and do not produce a significant quantity
of hydrochloric acid compared to the total U.S. production. The by-
product acid amounts for approximately 80 percent of the total U.S.
production.
In production of hydrochloric acid by chlorine burning, hydrogen and
chlorine are reacted in a vertical burner and the product
hydrogen/chloride formed is condensed in an absorber from which it flows
to a storage unit for collection and sale. A standard process diagram
is given in Figure 7.
Nitric acid
Practically all nitric acid is manufactured from ammonia by a catalytic
oxidation process. Ammonia is first catalytically oxidized to nitric
oxide, which is then further oxidized to nitrogen dioxide. The nitrogen
dioxide is then reacted with water to yield nitric acid. A standard
process diagram is presented in Figure 8. This study covers only
commercial 61-65% nitric acid. Fuming (i.e., more than 70%) nitric acid
and nitrogen pentoxide are made only at a few facilities and are not
covered in this report. Also not covered in this report is a minor
process for the production of nitric acid involving the reaction of
sodium nitrate and sulfuric acid.
Potassium
For the commercial preparation of potassium metal, potassium chloride is
melted in a gas fired melt pot and is fed to an exchange column as is
shown in Figure 9. The molten potassium chloride flows down over
Raschig rings in the packed column, where it is met by ascending sodium
vapors coming from a gas fired reboiler. An equilibrium is established
between the two, yielding sodium chloride and elemental potassium as the
products. The sodium chloride formed is continuously withdrawn at the
base of the apparatus and is normally sold. The column operating
40
-------
LIMESTONE—>
COKE
MIXING
WEIGHT
(DRY SCRUBBER...WASTE
-> C02 TO < PRECIPITATOR WASTE
I COLLECTION OR USE
CALCINING
COOLING
UNBURNED LIME
WATER VENT
LIME
PRODUCT
SLAKING
SCREENING
MILK OF LIME
Ca(OH)2
PRODUCT
R6URE 6
STANDARD
CALCIUM OXIDE (LIME) FLDW DIAGRAM
-------
HYDROGEN-
CHLORINE-
to
BURNER
PROCESS
WATER
COOLER
V ,
COOLING 22° Be
WATER ACID
PROCESS
WATER
VENT
ABSORBER
1
SCRUBBER
18° Be
ACID
| WEAK, ACID
|_(RECYCLED_ AT_$
EXEMPLARY PLANT)
FIGURE 7
STANDARD
HYDROCHLORIC ACID FLOW DIAGRAM (SYNTHETIC PROCESS)
-------
U!
AMMONIA
(ANHYDROUS)
EVAPORATOR
AIR-
COMPRESSOR
REACTOR
A
FILTER
WASTE
WATER GASES
A
COOLER
WEAK ACID
AIR
ABSORBER
V
NITRIC ACID
(61-65%)
FIGURE 8
STANDARD NITRIC ACID PROCESS FLOW DIAGRAM
-------
conditions may be varied to yield either pure potassium metal as an
overhead product or to vaporize sodium along with the potassium to
produce sodium-potassium (NaK) alloys of varying compositions.
Potassium metal of over 99.5% purity can be continuously produced.
Unlike lithium and sodium which are produced by electrolysis, potassium
reacts with carbon electrodes, and also can form an explosive carbonyl
in electrolysis. Therefore, the thermochemical route using the reaction
between sodium metal and potassium chloride has proved most practical
and economical. Production of potassium was about 90 metric tons per
year in 1972, essentially all of it originating from one facility.
Figure 9 describes this operation in which no process water is used and
from which there are no water-borne effluents.
Potassium dichrornate
Potassium dichromate is prepared by reaction of potassium chloride with
sodium dichromate. Potassium chloride is added to a dichromate
solution, which is then pH adjusted, saturated, filtered and vacuum
cooled to precipitate crystalline potassium dichromate which is
recovered by centrifuging, 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 to the initial reaction tank. Figure 10 is
the standard process diagram.
Potassium sulfate
The bulk of the potassium sulfate manufactured in the U.S. is prepared
by reaction of potassium chloride with dissolved langbeinite ore
(potassium sulfate-magnesium sulfate). The langbeinite is mined and
crushed and then dissolved in water to which potassium chloride is
added. Partial evaporation of the solution produces selective
precipitation of potassium sulfate which is recovered by centrifugation
or filtration from the brine liquor, dried and sold. The remaining
brine liquor is either discharged to an evaporation pond, reused as
process water or evaporated to dryness to recover magnesium chloride.
The fate of the brine liquor is determined by the saleability of the
magnesium chloride by-product and the cost of water to the plant. A
general process diagram is shown in Figure 11.
Sodium bicarbonate
Sodium bicarbonate is manufactured by the reaction of soda ash and
carbon dioxide in solution. The product bicarbonate is separated by
thickening and centrifugation and is then dried, purified and sold. A.
standard process diagram is shown in Figure 12.
Sodium chloride (solar salt)
44
-------
K (OR NdK) VAPOR
COLUMN
MOLTEN KCI
No VAPOR,
STAINLESS
STEEL
RASCHI6
RINGS
RECEIVER
V
CONDENSATION
K
(OR
NaK ALLOY)
-HEAT
FIGURE 9
COMMERCIAL EXTRACTION OF POTASSIUM
45
-------
RECYCLED LIQUOR
SODIUM
DICHROMATE
LIQUOR
KCI
REACTION
TANK
_y
FROM §,». TO
RIVER, j Q .RIVER
Jflt
MOTHER
LIQUOR ^.-^
MIX
TANK
FILTER
T
BAROMETRIC
CONDENSER
VACUUM
CRYSTALLIZER
PRODUCT
CENTRIFUGE
SALT
CONCENTRATOR
(STEAM
HEATED)
SALT
CENTRIFUGE
SODIUM
CHLORDE
SOLID
WASTE
FILTER
AID
WASTE
(SOLD)
DRYER
(STEAM
HEATED)
DRY PRODUCT DUST
_V
SIZER
PRODUCT
PACKAGING
DRY
DUST
COLLECTOR
FIGURE 10
STANDAND POTASSIUM DICHROMATE PROCESS FU3W DIAGRAM
-------
MINING
\
1
CRUSHING
LEACHING
V
DEWATERING
\L
DRYING
PRODUCT SIZING
i
\/
V
STANDARD
GRANULAR
SUSPENSION
PROCESS K-MAG
K-MAG (K2S04 -'
_y
GRINDING
MURIATE (KCI)
^
?
\
HYDR/
\
REAC
\
1
UMON L
/
TlflM
/2S°4
^ EVAPORATION
^. BRINE
^ WASTE
DRYING
REACTION SOLIDS
(HIGH GRADE K2S04)
GRANULATION
PRODUCT SIZING
_y
STANDARD
GRANULAR
FERTILIZER GRADE SULFATE
FIGURE 11
STANDARD POTASSIUM SULFATE PROCESS DIAGRAM
47
-------
SODA ASH WATER
r
4:
I
WASTE
CHARGING
MIXING
FEEDING
CARBONATING
_V
CENTRIFUGING
DRYING
COLLECTING
SCREENING
AND/OR
MILLING
PRODUCT
»TO
STORAGE
PRODUCT
>TO
STORAGE
RGURE 12
STANDARD SODIUM BICARBONATE PROCESS
FLOW DIAGRAM
-------
Sodium chloride is produced by three methods:
(1) solar evaporation of brine;
(2) solution mining of natural salt; and
(3) conventional mining of rock salt.
In the first two operations, there are wastes arising from recovered
product purifications. In the third case, the mined mineral is
frequently sold as-is to users. In some cases the rock salt is
purified, but in these cases, the methods used are the same as those
employed with solution mined brines. In this report, only the first two
methods of sodium chloride production are covered, as contacts with the
industry have revealed that there are no water-borne wastes normally
associated with mining operations.
In the solar evaporation process, salt water is concentrated by
evaporation over a period of five years in open ponds to yield a
saturated brine solution. After saturation is reached, the brine is
then fed to a crystallizer, wherein sodium chloride precipitates,
leaving behind a concentrated brine solution (bittern) consisting of
sodium, potassium and magnesium salts. The precipitated sodium chloride
is recovered for sale and the brine is then further evaporated to
recover additional sodium chloride values and is either stored,
discharged back to salt water or further worked to recover potassium and
magnesium salts. A process diagram is shown in Figure 13.
Sodium silicate
Sodium silicate is manufactured by the reaction of soda ash or anhydrous
sodium hydroxide with silica in a furnace, followed by dissolution of
the product in water under pressure to prepare sodium silicate
solutions. In some plants, the liquid silicate solutions are then
further reacted with sodium hydroxide to manufacture metasilicates which
are then isolated by evaporation as products. Figures 14 and 15 are
typical process diagrams.
Sulfuric acid
Sulfuric acid is manufactured primarily by the contact process, which
involves the burning of sulfur to sulfur dioxide, the catalytic
oxidation of sulfur dioxide to sulfur trioxide and reaction of the
sulfur trioxide with water to yield sulfuric acid. Within the contact
process, there are three subcategories of plants:
(a) double absorption - paired sulfur trioxide absorption
towers and catalyst beds in series are used to maximize conver-
sion of sulfur dioxide so that tail gas scrubbers are not re-
quired;
(b) single absorption - single absorption towers and cata-
lyst beds are used and tail gases frequently have to be scrubbed
to remove sulfur oxides;
(c) spent acid plants - these plants are spent sulfuric acid
49
-------
SEA WATER a 3°B*
1ST YEAR
CONCENTRATOR
I
BRINE fl 7.5° B4
M/
2ND YEAR
CONCENTRATOR
I
BRINE a 12° Bi
M/
3RD YEAR
CONCENTRATOR
I
BRINE a 16° Be
4TH YEAR
CONCENTRATOR
I
BRINE a 20° Bi
5TH YEAR
CONCENTRATOR
BRINE a 24.6° Bi SATURATED (PICKLE)
SALT DEPOSITED
FOR HARVEST
CRYSTALLIZER
RESIDUAL SALT
BRINE o 30° Be (BITTERN) ^^WATER*1
RESIDUAL SALT
DEPOSITED
HOLDING POND
^XXXXX X X X>
BRINE 0 32° Bi
I
I
STORAGE POND
BITTERN STORAGE
FIGURE 13
STANDARD SOLAR SALT PROCESS
FLOW DIAGRAM
50
-------
SILICA
SAND
SODA
ASH
WEIGHING
L
WEIGHING
J
MIXING
FURNACE
FLUE
WATER GAS
_L
>~» • »••
1
CONVEYOR
WASTE
HEAT
BOILER
WATER
.STEAM j ...EXCESS
PRESSURE
DISSOLVING
AIR VENT
RECEIVING
TANKS
PRODUCT
STORAGE
FIGURE 14
STANDARD LIQUID SODIUM SILICATE
FLOW DIAGRAM
51
-------
to
WATER STEAM AIR VENT
1 1 !
CYCl
SEPAF
WATER |
STEAM |
^/ Nl/
LIQUID SILICATE— >
AQUEOUS NoOH ^
V
WATER
PI ipi N
.ONE
?ATOR
^
DRYER
/
^
HOT Al
AIR
HEATER
. ^ 'tCRFTNIMft .
\f
— ' *-> SURGE
>» TANK
'
R ^ MM 1 |M(2 1
y
PRODUCT
>AIR VENT
T
AIR
RGURE 15
STANDARD ANHYDROUS SODIUM METASILICATE
FLOW DIAGRAM
-------
in place of, or in addition to, sulfur as a raw material. While
the acid production parts of these plants are the same as those
for single absorption, these plants are unique because of the
spent acid pyrolysis units used to convert the waste sulfur acid
raw materials to a sulfur dioxide feed stream.
In this program only the first two types of plants are considered. In
the double absorption contact process, sulfur is burned to yield sulfur
dioxide which is then passed through a catalytic converter with air to
produce sulfur trioxide. The sulfur trioxide is then absorbed in 95-97%
sulfuric acid. The gases emerging from the absorber are then fed to a
second converter to oxidize the remaining sulfur dioxide to sulfur
trioxide which is then absorbed in a second absorption tower, and the
tail gases are vented to the atmosphere.
As in other versions of the contact process, 95-97% sulfuric acid is
used in the absorption towers. Pickup of sulfur trioxide in this medium
converts it to 98% acid. Some of this acid is drawn off for sale and
the remainder is diluted back to 96-97% and recirculated through the
absorption towers. A process flow diagram is given in Figure 16.
The single absorption process differs from that previously described
only in the arrangement of the converters and absorbers. The rest of
the process is the same. For the single absorption process, the sulfur
dioxide is passed through one or more converters and then into one or
more absorbers prior to venting to the atmosphere as is shown in Figure
17. This arrangement is less effective for both conversion of sulfur
dioxide to sulfur trioxide and for absorption of the sulfur trioxide
into the absorber sulfuric acid. As a result, the tail gases may have
to be scrubbed and this may create a water-borne waste not present for
double absorption plants.
Category 2 chemicals
The manufacturing processes whose effluents are characterized by
suspended solids and no metals are described below.
Sodium
Sodium is manufactured by electrolysis of molten salt in a Downs Cell.
After salt purification to remove magnesium salts and sulfates, the
sodium chloride is dried and fed to a Downs electrolytic cell, where
calcium chloride is added to give a low-melting CaCl2 Nad eutectic,
which is then electrolyzed. Sodium is formed at one electrode,
collected as a liquid, filtered and sold. The chlorine liberated at the
other electrode is first dried with sulfuric acid and then purified,
compressed, liquefied and sold. A detailed standard process diagram is
given in Figure 18.
Sodium sulfite
53
-------
MOLTEN
SULFUR
DRED
AIR
S02 PRODUCTION
AND COOLING
H^S04 FOR
USE IN AIR '
DRYING TOWER
WASTE
HEAT
BOILER
•SOjr
BOILER/^
3LOWDOWN
—S02
rn
SOg
S03
I
ABSORPTION
TOWER NO. I
I
I
I J
SOg—S03 CONVERTER
I
PROCESS WATER
TOWER
ACID
ATMOSPHERE
ABSORPTION
TOWER NO. 2
y
HjS04
R
>
f
I
COOLING
WATER
t
v/imAJi_Mi ino —
SYSTEM
I
\
COOLING
f WATER
t
PRODUCT
ACID
FIGURE 16
SULFURIC ACID PLANT DOUBLE ABSORPTION
-------
AIR
SULFUR
\
AIR DR>
98% 1
-._ ^1 OLEUM A
01 *\ (OPTK
/
riNG IN AIR ^
H2S04 ->
_ AJR .
AIR _.
S03
BSORBER 1
DNAL). 1 v
eJ """" 1
S'L. J COOLER 1
°> 7£ , (OPTIONAL) j
1 ^
WATER y
OLEUM STORAGE , r
(OPTIONAL) tc
4
MELTING
v
BURNING
S02
WASTE HEAT BOILER
Si2
FILTER
S02
CONVERTER NO. 1
\f
AIR COOLER
S°2£S°3
CONVERTER NO. 2
s63
AIR COOLER
1
I
I/ATER VENT
T
\l/ 1 V
SCRUBBER
V
WASTE
)ILUTE H2S048 H2SC
^v
STEAM
™ s? o I LAM
. .^ WASTE(SOLID)
(SPENT CATALYST)
_ yP."""—^ J? BOILERS ^
(SPENT CATALYST)
HOT AIR TO BOILERS v,
S03
\k
X
_., , , \f „ -o
COOLER _ &5
1
\^/ WATER
) ) 98% ACID PRODUCT
FIGURE \7
STANDARD SULFURIC ACID SINGLE ABSORPTION
FLOW DIAGRAM (CONTACT PROCESS)
55
-------
SOLUTION
MINING
BaCI2
SATURATED
NaCI
SALT SCRUB
WASTE
CaCI
TO
PROCESS
ROCK
AND
DISSOLVE
NaCI
xl/
NaCI
BRINE
PURIFICATION
FILTRATION "
EVAPORATION
AND
FILTRATION
_V
DRYER
NaCI
xb
CI2
xb
COOLING
AND
DRYING
_y
PURIFICATION
AND
COMPRESSION
x
TO
SALE
WASTE
BAROMETRIC
CONDENSER
4
WASTE
ELECTROLYSIS
(DOWNS)
^
COOL
AND
FILTER
1 4
ASTE Na
WASTE
WASTE
LIME
EMERGENCY
LIME
ABSORPTION
WASTE
FIGURE 18
STANDARD CHLORINE-SODIUM DOWNS CELL
PROCESS FUDW DIAGRAM
56
-------
Sodium sulfite is manufactured by reaction of sulfur dioxide with soda
ash. The crude sulfite formed from this reaction is then purified,
filtered to remove insolubles from the purification step, crystallized,
dried and shipped. A standard process diagram is shown as Figure 19.
Hydrogen peroxide (Organic process)
Hydrogen peroxide is manufactured by three different processes: ( ) an
electrolytic process (b) an organic process involving the oxidation and
reduction of anthraguinone and (c) as a byproduct of acetone manufacture
from isopropyl alcohol. In this study only the first two processes are
covered. The third, presumably, will be covered in another study, along
with acetone manufacture.
In the organic process, anthraquinone is first catalytically
hydrogenated to yield a hydroanthraguinone then oxidized to
anthraquinone with peroxide being produced. The peroxide is extracted
from the reaction medium with water and the organic solvent and
anthraquinone are recycled. The recovered peroxide is then
concentrated, purified and shipped. A detailed general process flow
sheet is presented in Figure 20.
Calcium chloride
Calcium chloride is produced by extraction from natural brines. Some
material is also recovered as a by-product of soda ash manufacture by
the Solvay Process. The latter is discussed in the soda ash waste
treatment section since the partial recovery of calcium chloride is a
waste abatement procedure.
In the manufacture of calcium chloride from brines, the salts are
solution mined and the resulting brines are first partly evaporated to
remove sodium chloride by precipitation. The brine is then further
purified by addition of other materials to remove sodium, potassium and
magnesium salts by precipitation and further evaporation, and is th^n
evaporated to dryness. The recovered calcium chloride is then packaged
and sold. A standard process diagram is presented in Figure 21.
Sodium chloride (solution brine-mining)
Saturated brine for the production of evaporated salt is usually
obtained by pumping water into an underground salt deposit and removing
a saturated salt solution from an adjacent interconnected well, or from
the same well by means of an annular pipe. Besides sodium chloride, the
brine will normally contain some calcium sulfate, calcium chloride and
magnesium chloride and lesser amounts of other materials.
The chemical treatment given to brines varies from plant to plant
depending on impurities present. Typically, the brine may be first
aerated to remove hydrogen sulfide and, in many cases, small amounts of
57
-------
SODA ASH
SOLUTION
Cn
00
C0
REACTOR
TREATMENT
AND
FILTRATION
V
WASTE
^
CRYSTALLIZATION
SEPARATION
V
DRYING
1
PRODUCT
COOLER
COOLING
WATER
FIGURE 19
STANDARD SODIUM SULFITE PROCESS FLDW DIAGRAM
-------
RANEY ,
NICKEL
CATALYST HYDROGEN
WORKING FLUID
N^
SOH1 Q31H3AI
o
*
I
1
X
LL.
O
|
2
*
r~
i
IYDROGENATOR FILTER |
>
i
FILTER
A \
COOLING
WATER
' V
COOLER
uuuuuuu
N
t
OXIDIZING
VESSEL
WATER
f
EXTRACTION
TOWER
>
^— OXYGEN
f 20-25% H202
2
rN rnwrFMTRATOR
[RECYCLE y
, I5W/0 OF PRODUCT 5O"/o
r \r
DRYING TOWER
\
f
CLAY BED
N
i
NICKEL-SILVER
CATALYST BED
PURGE
WASTE
FIGURE 20
STANDARD
HYDROGEN PEROXIDE FLOW DIAGRAM
(RIEDL-PFLEIDERER PROCESS)
59
-------
SOLVAY WASTE LIQUOR,
OR PURIFIED BRINE '
MULTIPLE
EFFECT
EVAPORATOR
I
SODIUM
CHLORIDE
FINISHING
PAN
FLAKER
CALCIUM CALCIUM
CHLORIDE CHLORIDE
(SOLUTION) (SOLID)
FURNACE
CALCIUM
CHLORDE
(ANHYDROUS)
CALCIUM
CHLORIDE
(FLAKES)
FIGURE 21
STANDARD PROCESS FOR CALCIUM CHLORIDE MANUFACTURE
-------
chlorine are added to complete sulfide removal and oxidize all iron
salts present to the ferric state. The brine is then pumped to settling
tanks where it is treated with soda ash and caustic soda to remove most
of the calcium, magnesium and iron present as insoluble salts. After
clarification to remove these insolubles, the brine is then sent to
multiple effect evaporators. As water is removed, salt crystals form
and are removed as a slurry. After screening to remove lumps, the
slurry is then washed with fresh brine. By this washing, fine crystals
of calcium sulfate are removed from the mother liquor of the slurry and
returned to the evaporator. Eventually the calcium sulfate
concentration in the evaporator builds up to the point where it must be
removed by "boiling out" the evaporators.
The washed slurry is filtered, the mother liquor is returned to the
evaporators and the salt crystals from the filter are dried and
screened. Salt produced from a typical brine will be of 99.8 percent
purity or greater. Some plants do not treat the raw brine, but control
the calcium and magnesium impurities by watching the concentrations in
the evaporators and bleeding off sufficient brine to maintain a
predetermined level. By such methods, salt of better than 99.5 percent
purity can be made.
In either case, the final screening of the dried salt yields various
grades depending on particle size. A detailed process diagram is shown
in Figure 22.
Soda ash
Soda Ash is produced by two methods; mining and the Solvay Process. As
there are no water-borne wastes associated with the mining operations,
only the manufacture of soda ash by the Solvay Process was studied in
this program.
In this process, raw sodium chloride brine is purified to remove calcium
and magnesium compounds. It is then reacted with ammonia and carbon
dioxide, produced from limestone calcination, to yield crude sodium
bicarbonate which is recovered from the solution by filtration. The
bicarbonate is calcined to soda ash and the spent brine-ammonia solution
is reacted with slaked lime and distilled to recover ammonia values for
process recycle. The calcium chloride formed as a by-product during the
distillation is either discharged as a waste or partially recovered by
evaporation. A process flow diagram is given in Figure 23.
In this case, the process used is the same as that described in the
section on sodium bicarbonate. The adjacent soda ash plant serves
simply as a raw material source.
Category 3 chemicals
61
-------
HYDROGEN
to
BRINE-
AIR -!-
CAUSTIC
SODA
SODAASH>
BRINE-
SUL
/
IDE
v CHLC
AERATOR
>
> Ml)
>
/^D
\hn
>
RM
•s
X*
E
SETTLING
TANKS
\
Ml
(
JD
j
WATER
I
MULTIPLE-
EVAPORATORS
PURIFIED
BRINE
1
>» \WA*SHFW . >» Fll TFO
I
WASHOUT
(PERIODIC WASTE)
nmfc.ir- N
1
S ur\ i tr\ x^ owr\&iLnd
I
SODIUM
CHLORDE
' - un MIC.
(WASTE)
RGURE 22
STANDARD MULTIPLE-EFFECT EVAPORATION SODIUM CHIDRIDE
PROCESS FLOW DIAGRAM
-------
STEAM + C02
BRINE-
CO
BRINE
PURIFICATION
WASTE
(PURIFICATION MUDS,
CaC03, Mg(OH)2tETC.)
REACTOR
A
PRECIPITATOR
C02
LIME
KILN
LIMESTONE
/I
-1
7^
WATER
A
1
CALCINER
SODA ASH
STORAGE
SPENT BRINE
* NH4CI
S LAKER
-Ca(OH)2>
V
NH3
STILL
RECYCLE NH
V
WASTE(CaCI2 AND NaCI)
r--' OPTIONAL CaCl2 RECOVERY
EVAPORATOR
DRYING
FIGURE 23
v
WASTE
, CaCI2)
CaCI2
JPRODUCT |
SOLVAY PROCESS SODIUM CARBONATE FLOW DIAGRAM
-------
The processes whose effluents are characterized by suspended solids and
the presence of heavy metal salts are described as follows:
Chlorine - sodium (or potassium) hydroxide — diaphragm cell
In the diaphragm cell process, Figure 2Ht sodium chloride brines are
first purified by addition of sodium carbonate, lime flocculating agents
and barium carbonate in the amounts required to precipitate all the
magnesium, calcium and sulfate contents of the brine. The brine is
filtered to remove the precipitated materials and is then electrolyzed
in a diaphragm cell. Chlorine, formed at one electrode, is collected,
cooled, dried with sulfuric acid, then purified, compressed, liquified
and shipped. At the other electrode, sodium hydroxide is formed and
hydrogen is liberated. The hydrogen is cooled, purified, compressed and
sold and the sodium hydroxide formed, along with unreacted brine, is
then evaporated at 50% concentration. During partial evaporation, most
of the unreacted sodium chloride precipitates from the solution, which
is then filtered. The collected sodium chloride is recycled to the
process and the sodium hydroxide solutions are sold or further
evaporated to yield solid products.
For cases where potassium hydroxide is manufactured as a co-product with
chlorine, purified potassium chloride is used instead of sodium chloride
as the starting material. Otherwise, the process is identical.
Chlorine-sodium hydroxide (mercury cell)
Figure 25 shows a standard process diagram for sodium hydroxide/
chlorine production by the mercury cell process. The raw material salt,
is dissolved and purified by addition of barium chloride, soda ash, and
lime to remove magnesium and calcium salts and sulfates prior to
electrolysis. The insolubles formed on addition of the treatment
chemicals are filtered from the brine and the brine is fed to the
mercury cell, wherein chlorine is liberated at one electrode and a
sodium-mercury amalgam is formed at the other.
The chlorine formed is cooled, dried with sulfuric acid, purified to
remove chlorinated organics, compressed and sold. The mercurysodium
amalgam formed during electrolysis is sent to a denuder where it is
treated with water to decompose the amalgam forming sodium hydroxide and
hydrogen. The mercury is returned to the electrolysis cells. The
hydrogen liberated is cooled, scrubbed to remove traces of mercury,
compressed and sold.
The sodium hydroxide formed at the denuders is filtered, concentrated,
and sold. Waste brines emerging from the electrolysis cells are
reconcentrated and recycled as shown in Figure 25.
Chlorine-potassium hydroxide (mercury cell)
64
-------
SOLUTION
MINING
NaCI
ROCK
AND
DISSOLVE
UJ
10 -1
8 5
CM O
a a
Z Z X
NaCI
NaCU
WASTE
SOLAR
AND
DISSOLVE
V
WASTE
(INSOLUBLES
IN SALT)
BRINE
PURIFICATION
FILTRATION
SATURATION
NaCI
V
WASTE
(PURIFICATION MUDS
CaC03, Mg(OH), ETC J
NaCI
TO PROCESS
OR SALE
1
WATER
COOL
AND
TREAT
DIAPHRAGM
CELL
ELECTROLYSIS
NoOH
CU
50% EVAPORATION
AND
NaCI RECOVERY
T
VENT
98%
H2S04
1
SCRUBBER
COOLING
AND
DRYING
CI5
TO PROCESS
CI2
PRELIMINARY
PURIFICATION
AND
COMPRESSION
CI2
CI2
WASTE
UQUIFACTION
(OPTION)
CI2
LOW
PURITY
'Clz
SALE
V
WASTE WASTE
70%-80% (CHLORINATED
HYDROCARBONS)
H2S0
WASTE
(NaCI, NaOH)
50%
NaOH
SALE
SECONDARY
PURIFICATION
HIGH
PURITY
CI2
SALE
NaOH
CONCENTRATION
SOLID
NaOH
SALE
X = PROPRIETARY INGREDIENTS
(POLYELECTROLYTES,
FLOCCULANTS, ETC.)
FIGURE 24
STANDARD
CHLORINE-CAUSTIC SODA FLOW DIAGRAM - DIAPHRAGM CELL PROCESS
-------
a
Z
x
0 X
ROCK
AND
DISSOLVE
NaCI
WASTE
SOLAR
AND
DISSOLVE
*
WASTE
NaCI
\v
SOLUTION
MINING
NaCI ^
BRINE
PURIFICATION
FILTRATION
EVAPORATION
i
WASTE
X = PROPRIETARY INGREDIENTS
(POLYELECTROLYTES,
FLOCCULANTS, ETC.)
to
o
g
LU
IO £
g J .£J
W •• o
a Z a
Z O ffi
CONDENSATE
\f \f
1
SALT
SATURATION
PURIFICATION
1
\k
WASTE
Haf*
H2
*
•,
*
Ha CELL
ELECTROL
»-•-"' >"**!_
DENUDeR
SPENT SALT
i
(PURGE)
50%
NaOH
CAUSTIC
FILTRATION
WASTE
"2
COOL
TREAT
WASTE
COOLING
AND
DRYING
WASTE
TO PROCESS
PURIFICATION
OOMPRBNION
CI2 TO
WASTE
FIGURE 25
STANDARD
CHLORINE-CAUSTIC FLOW DIAGRAM MERCURY CELL PROCESS
-------
The flow diagram is the same used in the previous section, 4.3.2, except
potassium chloride is used as a raw material instead of sodium chloride.
Potassium chloride is normally purchased in purities of 98.4 to 99.5
percent. The potassium chloride is used to prepare a saturated brine
solution, to which may be added barium chloride and potassium carbonate
to remove magnesium and calcium salts and sulfates as insolubles, which
are then filtered from the brine and sent to waste treatment. The
purified brine is then electrolyzed in mercury cells, where chlorine is
liberated at one electrode and a potassium mercury amalgam is formed at
the other. Decomposition of the amalgam with water yields 50 to 55
percent potassium hydroxide, hydrogen and mercury. The mercury is
recycled to the electrolytic cells, the caustic solutions are cooled,
filtered and the potassium hydroxide values are then recovered. Waste
sludges from the potassium hydroxide recovery are sent to the abatement-
system. The hydrogen liberated by amalgam decomposition is cooled,
compressed and shipped. The condensates recovered from hydrogen
compression are sent to the waste abatement system.
The chlorine is dried, liquified and sold. The drying acid is sold or
reused and the wastes recovered from the chlorine liquefaction are sent
to the waste abatement system. Depleted brines from the electrolysis
are refortified with fresh potassium chloride and returned to the
purification step to minimize the amounts of potassium chloride lost in
the process.
Hydrochloric acid (with chlorine plant)
The process used is the same as discussed in the section on hydrochloric
acid. The chlorine plant at the same facility merely serves as a raw
material source.
Hydrogen peroxide - electrolytic process
In the electrolytic process for the production of hydrogen peroxide, a
solution of ammonium bisulfate is electrolyzed. Hydrogen is liberated
at the cathode and ammonium persulfate is formed at the anode. The
persulfate is then hydrolyzed to yield ammonium bisulfate and nydrogen
peroxide, which is then separated by fractionation from the solution.
The ammonium bisulfate solution is then recycled and the peroxide is
recovered for sale. The only waste is a stream of condensate from the
fractionation condenser. A detailed process flow sheet is shown in
Figure 26.
Sodium dichromate/sodium sulfate
Sodium dichromate is prepared by calcining a mixture of chrome ore
(FeO._Cr2O^) , soda ash and lime followed by water leaching and
acidification of the soluble chromates. The insoluble residue from the
leaching operation is recycled to leach out additional material.
67
-------
COOLING WATER
AMMONIUM
SULFATE
oo
r>
SERIES OF
ELECTROLYTIC
CELLS
A
Uo
A \
Y WATER
NODE LIQUOR WATER 7
EVAPO
1
CATHODE LIQUOR
-------
During the first acidification step, the chromate solution pH is
adjusted to precipitate calcium salts. Further acidification converts
the chromate to the dichromate and a subsequent evaporation step
crystallizes sodium sulfate (salt cake) out of the liquor. The sodium
sulfate is then dried and sold. The solutions remaining after sodium
sulfate removal are further evaporated to recover sodium dichromate. A
standard process flow sheet for sodium dichromate and sodium sulfate is
giv~n in Figure 27.
Titanium dioxide (sulfate process)
In the sulfate process, ground ilmenite ore (FeO.TiO2) is digested with
concen-t-rated sulfuric acid at high temperatures. The acid used is
normally about 150 percent of the weight of the ore. In some cases,
small amounts of antimony trioxide are also added. The resulting
sulfates of titanium and iron are then leached from the reaction mass
with water and any ferric salts present are reduced to ferrous salts by
treatment with iron scrap to prevent coloration of the final titanium
dioxide product.
After these operations, the solutions are clarified, cooled and sent to
a vacuum crystallizer. There, ferrous sulfate crystallizes out and is
separated from the mother liquor by centrifugation. This material is
either sold or disposed of as a waste.
The mother liquor is clarified by filtration after addition of filter
aids and further concentrated by vacuum evaporation. Seed crystals or
other nucleating agents are added and the concentrated liquor is treated
with steam to hydrolyze the titanyl sulfate present. Tnis precipitates
as acidic hydrated titanium. The precipitate is collected by
filtration, washed several times and calcined at 900-950°C to yield
titanium dioxide. This calcined product is ground, and further
processed to yield a purer product* A standard process flow diagram is
given in Figure 28.
Titanium dioxide (chloride process)
In the manufacture of titanium dioxide by the chloride process, titanium
dioxide-bearing ores are chlorinated to produce titanium tetrachloride,
which is purified to remove ore contaminants, and oxidized to form pure,
pigmentary titanium dioxide. The pigment is calcined, wet-treated,
milled, and packaged for sale.
The flowsheet of Figure 29 is typical of existing commercial chloride
process plants. Ores containing titanium dioxide, iron, aluminum,
vanadium, plus other minor trace impurities are dried to remove
moisture, then fed up to a high temperature fluidized bed chlorinator.
Coke needed to promote chlorination is also dried and fed to the
reactor. When chlorine is injected, the following typical reaction
occurs (written for ilmenite ore):
69
-------
CHROMITE
LIMESTONE ORE
i si
MILLING
SODA ASH-
_V
MIXING
V
CALCINING
V
CRUSHING
V
LEACHING
H2S04-
SODIUM
SULFATE
V
ACIDIFICATION
BY-PRODUCT
1
->
V
FILTERING
STEAM-
\/
EVAPORATING
_y
CRYSTALLIZING
I
WATER —
_S/
CENTRIFUGING
\/
DRYING
V
Na2Cr207-2H20
PACKING AND
SHIPPING
^
~i
->
SETTLING
SODIUM
SULFATE
BY-PRODUCT
FIGURE 27
STANDARD SODIUM DICHROMATE
PROCESS DIAGRAM
70
-------
ORE
STRONG H2S04-
TIN, WATER
DIGESTION
DISSOLVING
REDUCING
TiOS04, FeS04,H2S04, SLUDGE
FLOCCULANTS
V
CLARIFICATION
_V
SLUDGE TO
WASTE DISPOSAL
VACUUM
CRYSTALLIZER
_y
xFeS04-7H20
CENTRIFUGE
v
/\
COPPERAS TO
WASTE DISPOSAL
FILTER
VACUUM <-
_V
EVAPORATOR
WATER
Ti02
—»L
HYDROLYSIS
HYDRATE v^».
\f
CLEAN-UP FILTER
STRONG CUT TO
WASTE DISPOSAL
\/_
WASH 8 REDUCING
FILTERS
WATER REDUCING AGENT
3L
RECOVERY
V
\/
REPULP AND
WET TREATMENT
_\'
DRY
\S
FINISHED TI02< j_
MILLING
SALTS TO
WASTE DISPOSAL
->
FIGURE 28
STANDARD SULFATE PROCESS TITANIUM DIOXIDE
FLOW DIAGRAM
n
-------
ORE-
COKE-
->j DRYER | >
-^| DRYER | >
CHLORINATOR
A
UJ
ae.
o
FeClx,HCI, SOLIDS
TiCI4, FeCI3, COKE, ORE, C02, N2, C02
^
| COOLING TOWER |g
_V
ORE RECOVERY }g
V
CHEMICAL
TREATMENT
TiCI4
LIQUIFACTION
I ^ 1 SLUDGE
[TOWASTE DISPOSAL^
,*
W4ER
SCRUBBER
TiC,4
PURIFICATION
AIR, 02,N2, WATER
^
j 02 HEATER | [
TiCI4 VAPORIZER
\/
W
\S
TiCI4 HEATER
MAKE-UP CHLORINE-
-^
OXIDATION
REACTOR
v
RAPID COOLING
TO WASTE
DISPOSAL
V
Ti02, CI2, N2
CRUDE TK>2
COLLECTION
V
Ti02
SCRUBBER
T
i
CALCINER
WATER r-
TREATMENT AGENT—>|
\ /
> '
TREAT
FINISHED
Ti02<— j
MILLING
^
WASTE
FIGURE 29
STANDARD CHLORIDE PROCESS TITANIUM DIOXIDE
FLOW DIAGRAM
72
-------
C(s) * TiFeO3(s) + Cl2(g) — * TidU (g) + FeClx(g) + CO2(g) + CO (g)
The gaseous reaction products contain titanium tetrachloride, rerrous
and ferric chlorides, carbon monoxide and dioxide, hydrogen chloride
(from the hydrogen in the coke and ore, etc.) , entrained coke and ore,
plus all other chlorinated impurities in the ore. These pass to a long
cooling train which cools the product stream so that all of the iron
chlorides and most of the remaining metal chlorides condense. Solids
are separated from the gaseous titanium tetrachloride by centrifugation
or other mechanical means and slurried in water for discharge from the
process as raw waste.
The remaining gaseous titanium tetrachloride is then condensed. Non-
condensable reaction gases, containing small amounts of titanium
tetrachloride, silicon tetrachloride and hydrogen chloride, are water
scrubbed, then vented.
Crude titanium tetrachloride is purified to remove traces of silicon,
vanadium, iron, magnesium, manganese, aluminum, chromium, etc., by many
varied technigues including distillation, absorption, ion exchange, and
chemical precipitation with hydrogen sulfide, inorganic salts, or
organic compounds. A.11 methods yield a pure titanium tetrachloride
fraction, and a contaminate sludge which is slurried in water and
discharged with the cooling tower waste.
The pure titanium tetrachloride is vaporized, superheated, and added to
the oxidation reactor with hot air or oxygen to form a
pure, finely divided, pigmentary titanium dioxide according to:
Tie 14 + O2 — '* TiO +
The oxidation reactor product stream, consisting primarily of chlorine,
nitrogen, and suspended titanium dioxide is cooled and the titanium
dioxide separated mechanically by means of cyclones, bag filters, or
precipitators for further processing.
Chlorine and nitrogen from the oxidation product stream are fed to the
chlorinator with make-up chlorine to produce more titanium
tetrachloride. The recovered pigment is calcined and suface treated to
impart desirable optical or physical properties. The titanium dioxide
is ground to sub-micron sized particles, and packed as finished product.
73
-------
SECTION V
WATER USE AND WASTE CHARACTERIZATION
This section discusses the specific water uses in the Inorganic
Chemicals, Alkali and Chlorine Industry, and the amounts of waste
effluents contained in these waters. The process wastes are
characterized as raw waste loads emanating from a typical process before
treatment and the amount of water-borne waste effluent after treatment.
Also included in this discussion are verification sampling data measured
at specific exemplary plants for each chemical in the categories set
forth in Section IV. A description of the analytical techniques used
for this verification of plant data is also provided.
SPECIFIC WATER USES
Water is used in inorganic chemical processing plants for six principal
purposes plus other miscellaneous uses. The principal uses are:
1) Cooling — Non-contact cooling water
2) Process -- Contact cooling or heating water
Contact wash water
Transport water
Process and dilution water
Auxiliary process water
Th=> quantity of fresh water intake to plants in this industry generally
ranges from 38-75,700 cu m/day (10,000 GPD to 20,000,000 GPD) . In
general, the plants using very large guan.tities of water use it for
once-through cooling or as cooling water which is partially recycled.
Non-Contact Cooling Water
Many chemical processes operate more guickly or more efficiently at high
temperatures, or generate heat during exothermic reactions. cooling
water is often used to control or reduce these temperatures. If the
water is used without contacting the reactants, such as in a tube-in-
shell heat exchanger or trombone cooler, then the water will not be
contaminated with process effluent. If, however, the water contacts the
reactants, -"-hen contamination of the water results and the waste load
increases. Probably the single most important process waste control
technique, particularly with regard to feasibility and economics of
subsequent treatment, is segregation of non-contact cooling water from
contact cooling and process water.
The non-contact cooling water in the industry is generally of two types.
The first type is recycled cooling water which is cooled by cooling
towers or spray ponds. The second type is once-through cooling water
whose source is generally a river, lake or tidal estuary, and this water
is usually returned to the source from which it was taken.
75
-------
The only waste effluent from recycled water would be water treatment
chemicals and the cooling tower blowdown which generally is discharged
with the cooling water. The only waste effluent from the once- through
cooling water would be water treatment chemicals which are generally
discharged with the cooling water. The cooling water tower blowdown may
contain phosphates, nitrates, nitrites, sulfates and chromates. The
water treatment chemicals may consist of alum, hydrated lime, or alkali
metal ions (sodium or potassium) arising from ion exchange processes.
Regeneration of the ion exchange units is generally accomplished with
sodium chloride or sulfuric acid, depending upon the type of unit
employed.
Contact Cooling or Heating Water
This water comes under the general heading of process water because it
comes into direct contact with process reactants. Primary examples or
this type of water use are steam drum dryers and barometric condensers.
f'Tater is required in very large quantities for use in the barometric
condensers used to provide reduced pressure for the operation of
multiple effect evaporators. For a large "-riple-ef f ect evaporator such
as that used for salt evaporation, flews of 3,800-U1,600 cu m/day (1 to
11 million gallons per day) are not unusual. A waste etfluent problem
with the barometric condenser usage arises from the product vapors and
carry-over from the last effect (stage) of the evaporator which are
entrapped in the flow of condenser water. Because this conoenser wa^er
is normally used in high volume, it is usually discharged without
treatment.
Other direct contact cooling or heating water usage such as that for
contact steam drying, steam distillation, pump and furnace seals, etc.,
is generally of much lower volume than the barometric condenser water
and is easier to treat for waste effluents.
Contact Wash Water
water also comes under the heading of process water because it
comes into direct contact with either the raw material, reactants or
products. Examples of this type of water usage are ore washing to
remove fines, filter cake washing to remove entrained particles,
cleansing of insoluble product vapors, and absorption process wherein
water is reacted with a gaseous material to produce an aqueous solution.
Waste effluents can arise from all these washing sources, due to the
fact that the resultant solution or suspension may contain impurities or
may he too dilute a solution to reuse or recover and is thus discharged.
Transport Water
Water is often used in the inorganic chemical industry for transporting
reactants or products to various unit operations either in solution,
suspension or slurry form. A good example of this is solution-mined
76
-------
salt or brine. Water is pumped into a salt cavity at the rate of 3900
liters of water per kkg (936 gallons per ton) of salt. The salt is
dissolved, and the resulting brine is forced to the surface under
pressure where it can be fed to evaporators to produce dry salt, or fed
to electrolytic cells where it is used to produce chlorine and alkali.
Wastes resulting from these types of operations are generally dilute
solutions or suspensions which could be reused upon concentration or
could be returned to the source. In cases where transport water is
carrying a solid product, it normally is separated from the product by
filtration, evaporation, or drying. The resultant liquor or condensate
generally contains dissolved product, reactants or impurities, and often
is discharged.
Process and Product Water
The process or product water generally is that which comes in contact
with the product and stays with the product as an integral part.
Typical examples include digestion water used for sodium silicate
manufacture and water used in acid absorption towers. Likewise, water
may be added to a highly concentrated product to form a more dilute
product. The source of these waters is generally fresh water supplies,
steam condensate, dilute product streams, or a combination of these
sources. In general, waste loads from this water usage are minimal.
Auxiliary Process Water
This water is used in medium quantities by the typical plant for
auxiliary operations such as ion exchange regenerants, make-up water to
cooling towers with a resultant cooling tower blowdown, make-up water to
boilers with a resultant boiler blowdown, equipment washing, storage and
shipping tank washing, and spill and leak washdown. The water effluents
from these operations are generally low in quantity but highly
concentrated in waste materials.
Miscellaneous Water Uses
These water uses vary widely among the plants with general usage for
floor washing and cleanup, safety showers and eye wash stations,
sanitary uses, and storm run-off. The resultant streams are either not
contaminated or only slightly contaminated with wastes. The general
practice is to discharge such streams without treatment except for
sanitary waste. In instances where process residues collect where they
can be washed away by storm waters, as for example dusts on the exterior
of process buildings, storm run-off can constitute a serious
contamination problem.
PROCESS WASTE CHARACTERIZATION
Category 1 Chemicals
77
-------
Aluminum Chloride
Aluminum chloride is made by reaction of chlorine with molten aluminum.
The aluminum chloride formed vaporizes and is collected on air cooled
condensers. The tail gases leaving the condensers are the only source
of wastes downstream of the reaction zone. Plant 125 is the exemplary
plant for this product/process. Figure 30 shows a scrubber system for
this plant.
In the process described above, there are two sources of waste-
uncondensed aluminum chloride and chlorine in tail gases and unreacted
aluminum metal. At the exemplary facility, the first waste is utilized
to manufacture another product and the unreacted aluminum is disposed of
as a solid waste.
The raw waste loads are shown below:
Waste_Product Source kg/kkg^of Product_{lb/ton^
A1C13 Tail Gases 80 (160) 64-96 (128-192)
Unreacted Aluminum Reactor 22
At the exemplary plant there is an integrated blower system to exhaust
the plant, packing station, condensers, etc. All blower exhaust is
treated in an absorption tower where, as shown in Figure 30, the
aluminum chloride and chlorine vapors are absorbed into a recycling
scrubber system. From this scrubber, about 121 liters of solution per
kkg of product (29 gal/ton) are drawn off, filtered and further treated
to produce a 28% aluminum chloride solution which is sold. There are no
waste streams. The water input and use for the scrubber system is an
equivalent volume. This water is supplied from a well for makeup to the
system. None of this is recycled. It is used to make 28% solution
product.
The characteristics of the 28% aluminum chloride solution re
78
-------
VENT
t
DE MISTER
A
WATER MAKEUP
V
RECYCLE WATER
SCRUBBER
A
BLOWER
T
WASTE
GASES
BASE TANK
BLEED
TREATMENT TANK
STORAGE
28%
ALUMINUM
CHLORIDE
SOLUTION
FIGURE 30
SCRUBBER SYSTEM FOR TREATMENT OF
ALUMINUM CHLORIDE WASTES AT PLANT 125
-------
covered for sale are -tabulated below:
Aluminum Chloride Solution
ACS-0002
Technical Grade
A1C13 % 28 min.
Baume'at 15°C 32° min.
Total aluminum as aluminum oxide, % 10.5 min.
Color, APHA 100 max.
Free Aluminum, % 0.1 max.
Fe 25 mg/1
Heavy metals 10 mg/1
Sulfate 500 mg/1
Free Acidity as % HCl 0.2 max.
Freezing point -34 (-30)
Density at 15°C, g/cc (Ib/gal) 1.28 (10.7)
There are three types of aluminum chloride manufactured, all
from the same process:
1. Yellow -- this product is made using a slight excess
of chloride (0.0005%) and may contain some iron due
to reaction of the chlorine with the vessel.
2. White — this product has a stoichiometric aluminum/
chloride ratio.
3. Grey — this product contains 0.01% excess aluminum.
The unreacted aluminum raw waste load is higher for
the grey material.
Industrially, it generally makes little difference which ofa the above
grades is employed. In some pigment and dye intermediate applications,
however, the yellow material is preferred as it is free of elemental
aluminum.
There is no water-borne effluent for this facility. The only wastes are
air-borne.
Aluminum Sulfate
Aluminum sulfate is prepared by reaction of bauxite ore with sulfuric
acid. The ore and sulfuric acid are reacted in a digester and the
resulting aluminum sulfate solution, containing muds 'and other
insolubles from the ore, is then fed to a settling tank, wherein the
insolubles are removed by settling and filtration. The filtered product
liguor is either shipped as liquid aluminum sulfate solution or
evaporated to recover a solid product. There are two exemplary plants
for this product/process - plants 049 and 063. Figure 31 shows a de-
80
-------
BAUXITE SULFURIC ACID
1 1
WATER-
REACTION TANK
NO. I
REACTION TANK
NO. 2
_V
REACTION TANK
NO. 3
OVERFLOW
DILUTION
WATER
1
_y
CLARIFIER NO. I
UNDERFLOW
MUDS
LIQUID ALUM
PRODUCT STORAGE
STEAM HEATED
EVAPORATOR
(BATCH TYPE)
I I
V
CLARIFIER NO. 2
FLOOR WASHINGS
STEAM
DRY
ALUM
PRODUCT
_y
CLARIFIER NO. 3
PRIMARY
SETTLING POND
_y
CLEAR WATER
HOLDING POND
FIGURE 31
SULFATE PROCESS AND TREATMENT
FLOW DIAGRAM AT PUNT 063
81
-------
tailed process diagram including waste treatment
Figure 32 is a similar diagram for the other.
for one plant, and
Raw wastes from the process include muds (insolubles) from the digester,
settling tank and filtration unit as well as washwaters from vessel
cleanouts. At one facility these wastes are treated in a settling basin
to remove the muds and the waters and then recycled for reuse. A
similar recycling system is used in the other facility.
Raw wastes from aluminum sulfate manufacture are listed below:
Waste Products
Process Source
kg/kkg of Produce jib/ton^
Spent aluminum sulfate muds*
Low aluminum sulfate water
Mud washing
Mud washing
170 (340) (two different
100 (200) facilities)
800 (1600)
*The raw material bauxite contains 54-56% of soluble A12O3,
about 3,5% TiO2, about 5.5% SiO2, about 1.5% Fe2O3 and the
rest water of hydration. The muds have approximately the
following compositions: 40% SiO2, 40% TiO2, 20% A12O3,
0. 5% A12 (S04) 3.
At these plants all waters are fed to a settling basin where
muds are removed and impounded, and the clear effluent is
then used back in the process. A breakdown of water use at
both facilities is shown below:
Input
Type
Well
Well
049
063
Quantity
cu_rn/day_ liters/kkg
47 (12,400
GPD)
76 (20,000
GPD)
1650 (396 gal/ton)
2090 (500 gal/ton)
Comments
No Pretreatment
Required for
Either
Quantity
liter s/kkg
£rocess_Water
T.y.P§
Process 049 77 (20,400 2720 (652 gal/ton)
GPD)
Process 063 87 (23,000 2400 (575 gal/ton)
GPD)
% of Process
Stream Recycled
30*
All excess pro-
cess water*
*Remaining water shipped with product.
are made at both plants.
Aluminum sulfate solutions
82
-------
AIR
STEAM
WATER
00
N
BAUXITE
STORAGE
WATER
SULFURIC
ACID
STORAGE
, \
DIGESTER
ALUM
SKATER
AND
WASHED
>
f
SETTLING
TANK
\
i
WASH TANK
CLEAR
ALUM .
CLEAR
^LIQUID
"•^
MUD ^
FILTER
>
ALUMRED LIQUID ALUM
>w PRODUCT
STORAGE
WATER
AND MUD Y
TANK TRUCKS
f
WASH TANK
^ WATER AND MU
^ OVERFLOW WATE
v FROM POND
UNREACTED
BAUXITE
FIGURE 32
ALUMINUM SULFATE PROCESS AND TREATMENT
FLOW DIAGRAM AT PLANT 049
-------
These plants have no process or cooling water effluent.
Calcium Carbide
Calcium carbide is manufactured by the thermal reaction of calcium oxide
and coke. Calcium oxide and dried coke are reacted in a furnace, and
the product is then cooled, crushed, screened, packaged and shipped.
The only wastes from the process are air-borne dusts from the furnace,
coke dryer and screening bag filters. Bag filters are also now being
installed in the furnace and the packing areas. All collections are
returned to the furnace. The process locations of the sources of raw
waste in plant 190 are shown in Figure 33. A listing of the raw wastes
and amounts is given below. All but the cooling tower blowdowns are
treated, or will be treated by installations to be completed by July
1973, by dry collection methods. The blowdown wastes are intermittent
and are currently untreated. This data was furnished by the
manufacturer.
Waste,Product*
1. Fine Petroleum Coke
2. Stack Dust
3. Packing Dust
4. Cooling Tower Blowdown
Solids and cooling Water
Treatment Chemicals
kg/kkq of Product jib/ton^
Average Range
50 (100) 30-70 (60-140)
85 (170) 70-115 (140-230)
10 (20) 6-11 (12-22)
0.5-1 (1-2)
*The first waste is collected by bag filters and recycled.
Waste products 2 and 3 are now being exhausted to the air
but will be collected and recycled by bag filters similar
to those now collecting the coke fines when installation
is completed in July, 1973. The fourth waste is currently
untreated.
Figure 34 shows schematically the source and disposition of the water
usages at this exemplary plant. Table 3 lists the effluent wastes data
supplied by plant 190 and GTC's verification measurements. (These data
are the same as presented to the Corps of Engineers in plant 190's
permit application, except for pH and flow, which were obtained during a
plant visit) . Agreement for the one set of grab samples taken is
reasonably good. The sample was taken by plant personnel in the
presence of the GTC engineer, not by the GTC sampling crew, which did
not visit this facility.
84
-------
LIME
SILO
PET-
COKE
oo
Ul
DRYER
SILO
f
FURNACE
COLLECTOR
COOLING
WATER
it
COOL
CRUSH
SCREEN
PACKAGE
COLLECTOR
V V
SHIP
COLLECTOR
FIGURE 33
CALCIUM CARBIDE PROCESS FLOW DIAGRAM AT PLANT 190
-------
DOMESTIC SEWAGE
PROCESS TREATED WATER
1
I
TOTAL
RETENTION
LAGOON
PERSONNEL
SHOWERS
I . |
CITY WATER
BLOWDOWN<-
FI6URE 34
WATER USAGE AT PLANT 190
CALCIUM CARBIDE FACILITY
-------
TABLE 3. Plant Effluent from CaC.2 Manufacture
(All units ppm unless specified)
Intake Water
Parameter
Total suspended solids
Flow (cu m/day)
Total dissolved solids
Conductivity (as NaCl )
BOD
COD
pH
Alkalinity (as CaC03.)
Nitrate (as N)
Zinc
Phosphorus Total (phosphate)
Color (APHA Units)
Alumi num
Turbidity (FTU)
Fluoride
Total hardness (as CaCOJ.)
Calcium hardness (as CaC03)
Sulfate
Chloride
Iron
Chlorine (as C1JJ
Plant
Data
3.5
152
238
(c)
80
15
7.6
99
0.45
0.01
0.27
Nil
0.15
0
0.45
140
(c)
55
46
0.03
(c)
GTC
Veri fen,
0
(a,b)
(a)
95-100
(a)
25
7.5
90
0.27
(a)
0.32
10
(a)
5
(a)
136
118
51 .5
36
0.08
0
Cooling
Tower Hater
Plant GTC
Data Verifcn
48
13
1930
(c)
308
170
7.6
68
12
2.8
0.55
675
0.17
18
0.95
404
(c)
290
198
(c)
0
(a,b)
(a)
810
(a)
75
8.0
165
9.8
(a)
1 .30
20
(a)
10
(a)
750
675
690
95
0.019
0.1
(a) Not measured
(b) Flow varied frequently, depending on response of level-
monitoring valve
(c) Not in furnished data.
Note: Above data are not from split samples, but represent data
furnished for Corps of Engineer permit application approx-
imately two years prior to the verification measurements.
87
-------
Considerable amounts of chlorides and sulfat.es are discharged
intermittently due to cooling tower blowdowns and use of water treatment:
chemicals. These wastes could also be treated.
Plant 190's policy is to recover and recycle all possible air-borne
dusts by dry collection techniques. This approach eliminates all
process water wastes. The cooling tower blowdown and incoming water
treatment regenerants are the only water effluents. These non-process
water effluents are common to almost all inorganic chemical (as well as
many other) facilities. There is no process water effluent in this
exemplary plant.
Hydrochloric Acid
Hydrochloric acid is manufactured principally by two processes: (1) As a
by-product of organic chlorinations; and (2) By direct reaction of
chlorine with hydrogen. Our efforts for this chemical were limited to
the second process. In this process, hydrogen and chlorine are reacted
in a vertical burner. The hydrogen chloride formed is condensed in an
absorber from which it flows to a storage unit for collection and sale.
The arrangement used at the exemplary facility (plant 121) is similar to
the standard, flow diagram shown in Section IV. The special waste
treatment system used during startup of this facility startup is shown
in Figure 35.
Raw Waste Load
The raw waste loads from hydrochloric acid manufacture are presented
below. Some of these are markedly dependent on conditions, with most of
the wastes being produced during startups. There are no water-borne
wastes during periods of normal' operation.
88
-------
STARTUP-
WASTE
NaOH + WATER VENT
1 t
SCRUBBER
WATER
Cl
ABSORBER
2
NaOH + WATER u
oa:
NEUTRALIZATION
VESSEL
UJ
o
CO
a
o
o
o
EFFLUENT
RGURE 35
STARTUP WASTE TREATMENT SYSTEM
AT PLANT 121
89
-------
Waste_Products Process Source Amount of Product
1. Chlorine* Burner Run - Startup - 100 kg/kkg(200 lb/
Chlorine-rich ton) avg. 5-200 range(10-400)
Operation - 5 kg/kkg(10 lb/
ton) avg. 0-10 range(0-20)
Shutdown - no waste
2. HC1** - Startup - U.5 kg/day(9 Ib/ton)
Operation - none
Shutdown - none
3. NaOH*** Neutralization Startup - depends on HC1
reaction and C12 to be neutralized
products Operation - none
(NaCl and Shutdown - none
NaOCl)
*Emerges in vent gas during normal operation, neutralized
during startup by NaOH.
**All neutralized during startup.
***Caustic (NaOH) used has 12% NaCl present and is cell liquor
. from chlorine plant also in the complex.
90
-------
Water Use and Treatment
All treatment is performed during startup of the facility.
During normal operation, there are no water-borne wastes to
be treated. Water use at the facility is listed below:
A. Input
Type
Lake
Well
Quantity
5,680
(150,000
GPD)
1,135
(30,000
GPD)
15,650
(3,750 gal/
ton)
3,130
(750 gal/ton)
Comments on Content
TDS-300 mg/1, SS-10 mg/1,
Cl-65 mg/1, SO4-3U mg/1,
CaCQ3_-200 mg/1, Ca(HCO.3)2-
2-250 mg/1. ~"
Same as lake water except
lower in sulfate, low SS
(less than 10 mg/1).
B- Water Use
Type
Cooling*
Process
Disposal
from neut-
ralization
tank**
Miscellan-
1,135
(30,000
GPD)
760
(20,000
GPD)
U.5U5
(120,000
GPD)
QuantitY
liters/kkg
3,130
(750 gal/ton)
2,085
(500 gal/ton)
12,520
(300 gal/ton)
380 1,OUO
(10,000 (250 gal/ton)
GPD)
(Leaves as part
of product)
0
*Phosphate treatment used for this water. About 0.5 mg/1
excess phosphate is employed.
**For safety purposes, continuous water flow is maintained
into the neutralization tank even during normal process
operation when no effluent or NaOH are introduced.
91
-------
The effluents from the process streams before sewer at plant
121 are listed below.
Stream No.
1. Neutralizing
Reactor
2. Neutralizing
Siphon Tank*
3. Test Sink and
Washdown
4. Cooling Water 1,135 (30,000 GPD)
cu m/day
4,355 (115,000 GPD) 12,000 (2,875 gal/ton)
520 (125 gal/ton)
1,040 (250 gal/ton)
3,130 (750 gal/ton)
190 (5,000 GPD)
380 (10,000 GPD)
*Siphon Tank is 26,500 liters and has less than 4 liters drainage per
day. It is operated batchwise with excess caustic always present. When
the alkali content has been neutralized, it is disposed of.
After treatment, these streams are fed to a common equalization pond for
pH adjustment and suspended solids settling prior to discharge.
Effluent after this treatment (for the total complex) contains less than
10 mg/1 of suspended solids and 2588 mg/1 chlorides and sulfates, mostly
from other processes.
The plant effluent characteristics are given below. There are no wastes
during normal operation. All of the wastes arise from startup opera-
tions. In addition, there is an air-borne chlorine vent gas waste as
noted earlier.
Parameter
Total
Suspended
Solids
Total
Dissolved
Solids
BOD
COD
pH
Stream No. 1 Stream No. 2 Stream
Oger at ion/Startup Operation/Startup No_.__3 NgJ
10*mg/l 10 mg/1 No
Effluent
300*mg/l 40,000-
50,000
0 mg/1 10 mg/1
0 mg/1 0 mg/1
6.5-10.0 6.5-10.0
9 avg. 9 avg.
Batch
for a
number
of pro-
cesses;
90-180 kg
of C12 neu-
tralized per
month and
disposed of
in this
stream
Same as lake
water
*Same as lake water
All of the chlorine-burning HCl plants for this study are located within
chlor-alkali complexes. At present, there are four such facilities: 1.
92
-------
Pennwalt - Portland Oregon 2. Detrex - Ashtabula, Ohio 3. Vulcan
Newark, New Jersey u. Hooker - Montague, Michigan
The 121 plant is exemplary because of two considerations: 1) Unlike the
other facilities, hydrochloric acid wastes are easily segregable. At
other plants these wastes are mixed with chlor-alkali wastes.before
treatment; and 2) Unlike some other facilities, there are no hydro-
chloric acid wastes during normal operations.
Sampling of this facility presented problems in that all waste
discharges occurred only during plant startup.
This facility could be further improved by: (1) More efficient scrubbing
of process tail gases to remove chlorine and use of the resulting
chloride/hydrochloric solutions formed elsewhere in the facility; and
(2) Reuse of the sodium chloride formed by acid neutralization.
Hydrofluoric Acid
Hydrofluoric acid is manufactured by reaction of sulfuric acid with
fluorspar ore (mainly calcium fluoride). The reaction mixture is heated
and the hydrofluoric acid leaves the furnace as a gas, which is cooled,
condensed and sent to a purification unit. There the crude hydrofluoric
acid is redistilled and either absorbed in water to yield aqueous
hydrofluoric acid or compressed and bottled for sale as anhydrous
hydrofluoric acid.
At an exemplary plant (plant 152), the calcium sulfate byproduct from
the reactor is slurried with water and sent to waste treatment. Also,
all tail gases are scrubbed and the scrubbed water sent to the waste
abatement system. A general process flow sheet was shown earlier,
Section IV, Figure 5. Figure 36 shows a detailed process diagram for
the exemplary facility, and Figure 37 shows the wastewater recycling
system in use at this plant.
The waste product from hydrofluoric acid manufacture are shown below.
Wastes consist of materials from the furnaces, which include calcium
sulfate, calcium fluoride and sulfuric acid, plus fluoride-containing
scrubber wastes.
93
-------
FLUORSPAR
GAS FUEL
AND AIR
1
FEED BIN COMBUSTION
r-ttu °m CHAMBER
COOLING WATER
4 V V
THREE
VV9* ""T*8 -* B°o1f -> "«<»•« -*
PARALLEL
\l/ ~~7
RESIDUE
CaS04 TO
TRENCH AND
RECYCLE
2
-------
SETTLING
POND
A
SETTLING
POND
A
CLEAR
WATER
POND
RECYCLE
WATER
PUMP
FURNACE
FURNACE
FURNACE
NEUTRALIZING
PIT
V
NEUTRALIZED RESIDUE SLURRY
FIGURE 37
EFFLUENT RECYCLE SYSTEM AT PLANT 152
-------
Waste Products Process SourceAverage kg/kkg of Product (lb/ton
1. CaS04 Kiln (reactor) 3,620 (7,240)
2. H2SCW Kiln (reactor) 110 (220)
3. CaF2~ Kiln (reactor) 63 (126)
4. HF Kiln (reactor) 1.5 (3)
5. H2SiF6 Scrubber 12.5 (25)
6. Si02 Kiln (reactor) 12.5 (25)
7. SO2 Scrubber 5 (10)
8. HF Scrubber 1 (2)
The water use within plant 152 is shown below.
Ty_p_e Total Quality
cu m/day (GPD) liters/kkq^gal/ton)
Cooling 3,270(864,000) 90,140(21,600) 0
(river water)
Slurry and 3,270(864,000) 90,140(21,600) 100
Scrubber
All process , and scrubber waste waters are totally recycled in the
exemplary plant. The waters used to slurry and remove the calcium
sulfate from the furnaces and scrubber waters are fed to a pond system
after being treated with caustic or soda ash and lime to precipitate
fluorides and adjust the pH. In the pond system, the insolubles are
settled out and the waters are then reused in the process as shown in
Figure 37.
Only cooling water is discharged from this facility. Table 4 shows the
compositions of process waters before and after neutralization and of
the river intake water which is essentially the same as the cooling
water effluent. Low fluoride levels are easily maintained because of
segregation of discharged cooling waters from the process water.
Verification measurements, shown for the plant intake water and the
outflow of cooling water, are given in Table 5. These data verify that
there is no fluoride discharge from this facility. The similarity of
the intake and cooling water discharge verifies that there is no process
water leakage into the cooling stream, and therefore there is no process
water discharge from this exemplary hydrofluoric acid manufacturing
plant.
Calcium Oxide and Calcium Hydroxide
Calcium oxide is manufactured by thermal decomposition of limestone in a
kiln. The limestone is first crushed, then added to the kiln, wherein
it is calcined to effect decomposition. The product is then removed
96
-------
TABLE 4.
Intake Water and
at Plant 152*
Units
Raw Waste Composition Data
mg/1
mg/1
Parameters
Aluminum Al
Beryllium Be
Calcium Ca
Cadmium Cd
Cobalt Co
Chromium Cr
Copper Cu
Iron Fe
Magnesium Mg
Manganese Mn
Molybdenum Mo
Nickel N i
Lead Pb
Titanium T i
Zinc , Z n
Barium Ba
Potassium K
Sodium Na
Tin Sn
Ammonia-Nitrogen
COD
Fluori de
Total Suspd Solids
Total Solids
Total Vol. Solids
Total Dissolved
Solids
Nitrate
Nitrite
Ni trogen-Kjeldahl
Phosphate Total
Sulfate
Arsenic
PH
TOC mg/1
*Data furnished by manufacturer
mg/1
mg/1 N
02
mg/1 N
mg/1 P
mg/1 S
Raw Waste
Into
Treatment
7400
66
640
16
300
46
44
3100
6.0
100
56
80
1320
240
1100
740
6.4
490
140
0.23
13.4
13.0
16596
22015
1220
4250
0.26
0.02
0.57
1 .60
880
77
3.86
4
Recycle
Water From
Treatment
2200
64
450
12
280
22
28
780
6.4
106
56
68
3400
220
880
1020
8.6
660
140
0.05
_
12.5
59
3758
340
3572
0.20
0.01
0.46
0.96
767
49
7.22
6
Intake
River
Water
2600
20
12.2
2
26
4
4
1060
3.2
68
26
4
820
20
440
1280
0.6
4.2
24
0.23
_
0.2
21
124
58
132
0.13
0.20
0.46
0.02
7
74
7.17
5
97
-------
TABLE 5. Comparison of Plant Intake Water and
Cooling Water Discharge at Plant 152*
Parameter
Flow
Temperature
Color (Apparent)
Turbidi ty
Conductivity
Suspended Solids
pH
Acidity: Total
Free
Alkalinity (Total)
Hardness: Total
Halogens: Chlorine
Fluoride
Sulfate'
Nitrogen (Total)
Heavy Metals:
Iron
Chromate (Cr+6)
Oxygen (Dissolved)
COD
P
T
Intake
Not Measured
Not Measured
50
19
65
135
7
7.40
0
0
0
0
50
0
0.2
25
0.20
0.25
0.02
11
25
Pi scharge
Units
3,270
(864,000)
18 (64)
50
19
65
135
12
7.50
0
0
0
30
50
0
0.2
22
0.14
cu m/day
(GPD)
°C (°F)
Units APHA
FTU
mg/1 NaCl
mi cromhos/cm
mg/1
-
mg/1 CaC03_
mg/1 CaC03
mg/1 CaC03
mg/1 CaC03_
mg/1 CaC02
mg/1 C12
mg/1 F-~
mg/1 S04-2
mg/1 N
0.25 mg/1 Fe
0.02 mg/1 Cr+6
10.4 mg/1 02
0 mg/1
*Data from GTC verification sampling
98
-------
from the kilns, marketed as is, or slaked by reaction with water and
then marketed. A process flowchart is given in Figure 38 descriptive of
the general process at the exemplary plant (plant 007).
The raw wastes produced from calcium oxide manufacture are shown below.
These consist of fine dusts collected from the plant gas effluent, by
scrubbing systems. At the exemplary facility this dust removal is
achieved by use of bag filters and other dry particulate collection
equipment. No wet scrubbing techniques are employed. Wet scrubbing of
these dusts is used commonly at non-exemplary plants.
kg/kkg of
Waste_Product Process Source Product (Ib/ton)
Dry Particulate Matter Kiln gases 67 (133) (no effects
(Dry collector) of startup & shut-
down)
Exemplary plant water usage is described below. All cooling water is
recycled and all process water is consumed in the manufacture of due to
the use of -dry waste collection techniques, there is no waterborne
effluent from the facility. This plant achieves ninety-five percent or
better solids collection at the kiln collector. Municipal water intake
to the plant amounts to 638 liters of product (153 gal/ton) plus the
amount evaporated on the cooling tower. This water is not further
treated in the plant prior to use.
This amount of water represents the process water, that is the water
used in the hydrator. The cooling water flow for the bearings on the
tube mill and pistons on the hydrator pump amounts to 1,000 liters per
metric ton of product (240 gal/ton) on an average and it is completely
recycled with makeup water added to compensate for evaporation.
There is no waterborne effluent.
Nitric Acid
Nitric acid is manufactured from ammonia by a catalytic oxidation
process. Ammonia is first catalytically oxidized to nitric oxide, which
is then further oxidized to nitrogen dioxide. The nitrogen dioxide is
then reacted with water under pressure to yield nitric acid. The
exemplary plant (plant 114) manufactures only commercial 63% nitric
acid. Fuming (i.e., more than 70%) nitric acid and nitrogen pentoxide
are made only at a few facilities and are not covered in this report.
The flow diagram for plant 11U is given in Figure 39.
99
-------
LIMESTONE
NATURAL GAS-
KILN
AIR
COOLER
QUICKLIME •
VENT
A
HAMMER
MILL
DRY
BAG
COLLECTOR
HYDRATOR
PRODUCT RECOVERY
BULK
HYDRATED
LIME
STORAGE
PARTICLE
SIZING
, KILN GASES
PARTICULATE
MATTER
VENT
t
DRY
BAG
COLLECTORS
SOLID
WASTE
MAKE-UP
WATER
COOLING WATER
COOLING
TOWER
— PROCESS WATER
NON-CONTACT
COOLING WATER
HYDRATED
LIME
PACKAGING
FIGURE 38
FLOW DIAGRAM FOR LIME PLANT 007
100
-------
AMMONIA
AIR
COOLING WATER
EVAPORATOR
COMPRESSOR
_y
MIST ELIMINATOR
LOW PRESSURE
STEAM - •
CONDENSATE
TO TANK
FILTER
SUPER HEATER
FILTER
\/
MIXER
_V
BURNER
_V
TURBINE GAS HEATER
V
HIGH PRESSURE STEAM.
TO STEAM TURBINE
BURNER GAS BOILER
CATALYST
RECOVERY FILTER
TAIL GAS TO CATALYTIC
COMBUSTER, GAS EXPANDER,^-
TURBINE GAS BOILER ^ '
AND VENT.
TAIL GAS HEATER
FEED WATER-
COOLING WATER
COOLING WATER.
COOLING WATER^,
_y
FEED WATER HEATER
_y
NITRIC GAS COOLER
WEAK ACID CONDENSER
ABSORPTION TOWER
\/
BLEACH AIR COOLER
LOW
PRESSURE
STEAM
TAIL GAS PREHEATER
-------
The raw waste load from nitric acid production at the exemplary plant- is
listed below. There are no nitrates in the waste. All weak nitric acid
lost in manufacture is recycled to the process at this facility. The
wastes consist only of water treatment chemicals used for the cooling
water.
Waste Products E£2£§§s_Source Avg,. kg/kkg_HNO3_(lb/t:on) *
1. Lime
2. Calcium and
Magnesium
Carbonates
3. Disodium
Phosphate
4. Sodium Sulfate
5. Sulfuric Acid
6. Chlorine
Boiler Feedwater
Boiler Feedwater
Boiler
Boiler
Cooling Tower
Cooling Water
Treatment
0.47 (0.94)
0.6 (1.2)
0.0016 (0.0032)
0.0008 (0.0016)
0.0016 (0.0032)
1.0 (2.0)
*Values not affected by startup and shutdown
102
-------
Treatment at. Exemplary^Plant
Plant water use is shown below and describes the large amount
of water and weak acid recycling at the plant. Only cooling
water is discharged, and this waste stream is currently un-
treated. A settling basin may be installed in the future at
plant 114 to settle out suspended materials from the cooling
water prior to discharge.
Wa te r_ In JDU t s
well
Water_Use
Cooling
Process stream
cu m/day_
3,815
(1,008,000 GPD)
liter_s/kkg
13,150
(3,150 gal/ton)
cu m/day
31,000
(8,000,000 GPD)
775
(200,000 GPD)
liters/kkg
106,800
(25,000 gal/ton)
2,670
(6,250 gal/ton)
95
75**
**Recycled weak nitric acid from condensates, etc. is
89 cu m/day (23,000 GPD)
Effluent from Exemplary Plant
The plant effluent streams are shown below. Wastes discharged
are only water treatment chemicals.
Sources
Boiler Feedwater
Treatment
Boiler Slowdowns
Tower Water
Slowdowns
cu m/day
(1,250 GPD)
30
(7,800 GPD)
3600
(95,000 GPD)
liter/kkg
16
(3.9 gal/ton)
85
(2 4. 4 gal/ton)
1240
(297.0 gal/ton)
(All streams tie into common effluen-t header before discharge)
Because of recycling of some water and of all nitrogen-
containing streams, this plant is exemplary. However, as in
many other cases, cooling waters are untreated prior to dis-
charge. The plant effluents are listed below.
103
-------
Average
Range
Units
Total Suspended Solids
Total Dissolved Solids
BOD
COD
PH
Temperature
Turbidity
Color
Conductivity
Alkalinity (Total)
Hardness (Total)
Chloride
Fluoride
Sulfite
Sulfate
Phosphates
Nitrate
Iron
Manganese
80
239
5
10
7.8
25
125
330
500
300
300
18
0.2
0.2
60
0.4
0.2
7.5
0.2
50-100
200-250
7.5-8.5
24-27
mg/1
mg/1
mg/1 (O2)
mg/1 (02)
°C
JTU
PTCO
mhos
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
mg/I
mg/1
A plant visit verified that only cooling water is discharged
from plant 114.
Potassium Metal
For the commercial preparation of potassium metal (K), potassium
chloride is melted in a gas-fired melt pot and is fed to an exchange
column, as was shown in the standard process flow diagram. Figure 9, in
Section IV. The molten potassium chloride flows down over steel Raschig
rings in the packed column, where it is contacted by ascending sodium
vapors coming from a gas-fired reboiler. An equilibrium is established
between the two, yielding sodium chloride and elemental potassium as the
products. The sodium chloride formed is continuously withdrawn at the
base of the apparatus and is normally sold. The column operating
conditions may be varied to yield either pure potassium metal as an
overhead product or to vaporize^ sodium along with the potassium to
produce sodium potassium (NaK) alloys of varying compositions.
Potassium metal of over 99.5% purity can be continuously produced by
this process.
Production of potassium in the United States was about 90 kkg/yr (100
tons/yr) in 1972, essentially all of it originating from one facility
plant 045. Contacts with this manufacturer have revealed that the
process diagram accurately describes their operation in which no process
water is used and from which there are no waterborne effluents. Hence,
there appear to be no waterborne effluent streams from the manufacture
of this material.
104
-------
Potassium Dichromate
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 pioduc- is
recovered by centrif ugation , dried, sized and packaged. The moth°r
liguor 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 zeaction
tank. The exemplary plant is plant 002, and its process flow diagram is
the same as Figure 10, Section IV, the standard flow diagram.
Raw Waste Loads
The raw wastes from potassium dichromate manufacture are listed below.
These are crystalline sodium chloride and filter aids which are solid
wastes and are hauled away for landfill disposal by a contractor.
H^st^ Products Process Sourcekg/kkg of Product __ lib/ton
NaCl Centrifuge 400 (800)
Filter aid Filter 0.85 (1.7)
Exemplary plant water usage is given below. All process waters are re-
cycled. The only wastes currently discharged emanate from contamination
of once-through cooling water used on the barometric condensers on the
product crystallizer. Plant 002 has plans to replace the barometric
condensers with heat exchangers using non-contact cooling water by the
end of 1973. This should eliminate the hexavalent chromium waste
completely. With this change, no process waters will be discharged.
A. Water Inputs to Plant
Type ________ QuaQtiiY _______ Comments
cu_m/day_ liters/kkg
Fiver 1,325 97,200 Untreated except for
(350,000 GPD) (23,300 gal/ton) macrof iltration
Municipal 245 18,100 Untreated
(65,000 GPD) (4,330 gal/ton)
cu m/day liters/kkg
Cooling 1,325 ' 97,200 0
(350,000 GPD) (23,300 gal/ton)
Process 245 18,100 100
(makeup) (65,000 GPD) (4,330 gal/ton)
105
-------
Presently, the only effluent from this plant is cooling water, possibly
contaminated with hexavalent. chromium in the barometric condenser.
Replacement of the condenser with a non-contact heat exchanger will
eliminate cooling water contamination, although a larger amount of water
will have to be used for the less efficient non-contact: heat exchanger.
Potassium Sulfate
The bulk of the potassium sulfate manufactured in the United States is
prepared by reaction of potassium chloride with dissolved langbeinite
(potassium sulfate-magnesium sulfate). The langbeinite is mined and
crushed and then dissolved in water to which potassium chloride is
added. Partial evaporation of the solution produces selective
precipitation of potassium sulfate which is recovered by centrifugation
or filtration from the brine liquor, dried and sold. The remaining
brine liquor is either discharged to an evaporation pond, reused as
orocess water or evaporated to dryness to recover magnesium chloride.
The fate of the brine liquor is determined by the saleability of the
magnesium chloride by-product (depending on ore quality) and the cost of
water to the plant. A diagram for the process used at the exemplary
facility (plant 118) is given in Figure 40.
The table below presents a list of the raw wastes expected
for potassium sulfate manufacture:
Waste_Product Process Source kg/kkg of Product jib/ton^
Average Range
Muds,(silica, alumina. Dissolution of 15-30
clay and other langbeinite ore (30-60)
insolubles)
Brine liquor Liquor remaining - 0-2000*
(Saturated magnesium after removal of
chloride solution) potassium sulfate
*Part of the magnesium chloride is recovered for sale and part
of the remaining brine solution is recycled for process water.
The high value corresponds to the case of no recycling or recovery of
magnesium chloride. These brines contain about 33% solids. The wastes
consist of muds from the ore dissolution and waste magnesium chloride
brines and are not affected by startup or shutdown. The latter brine
can sometimes be used for magnesium chloride production if high grade
langbeinite ore was used. composition of the brine solutions after
potassium sulfate recovery is:
Potassium 3.19%
Sodium 1.3%
Magnesium 5.7%
Chloride 18.5%
Sulfate 4.9%
Water 66.7%
106
-------
WATER
KCI
DISSOLVER
LANGBEINITE ORE-
FILTRATION
REACTOR
> WASTE MUDS
FILTRATION
PARTIAL
EVAPORATION
PRODUCT
BRINE LIQUOR FOR RE-USE
WATER
VAPOR
EVAPORATOR
\/
CLARIFIER
PRODUCT
MgCI2
FIGURE 40
POTASSIUM SULFATE PROCESS DIAGRAM AT PLANT 118
-------
The amount of brine produced is about 650 kg of solids/kkg of potassium
sulfate (1300 Ib/ton) after evaporation. For higher grade ores, the
sodium content is lower. The data presented above were supplied by
plant 118.
The muds listed above are separated from the brine solutions at this
exemplary plant by filtration after dissolution of the langbeinite ore.
These are recovered and disposed of as landfill on the plant site. The
brine wastes, containing mostly magnesium chloride, are either disposed
of or treated in three different manners:
1. Evaporation with recovery of magnesium chloride for sale. This is
practiced only when high grade ores are processed.
2. Reuse of the brine solution in the process in place of using process
water. This is normally done to a considerable extent.
3. Disposal of the brines in evaporation pits.
At plant 118, all three of the above options are practiced, depending on
the guality of the ore being processed.
Water use at plant 11R is described below:
Wa t er _I.np_ut s :
Type __________ Qy.Miii.tY _____ Water Purity
1/kkg (gal/ton)
Well Water 3,790 (1.0) 8,360 (2,000) 40 mg/1 total
solids
_Fl ows :
Ty_oe _________ Quantity _________ % Recycled
Cooling 13,600 (3.6) 30,000 (7,200) 60-70% (remainder
evaporated)
Process 2,270 (0.6) 5,010 (1,200) 67% recycled, 3354
lost either by
evaporation or re
moval from system
with product or
by-product.
There are no effluent streams from the plant since much of the
water is recycled. Most of the water losses occur during the
process evaporation steps.
108
-------
Sodium Bicarbonaf.e
Sodium bicarbonate is manufactured by the reaction of soda ash
and carbon dioxide in solution. The product bicarbonate is
separated by thickening and centrifugation and is then dried,
purified and sold. A detailed process diagram for the exem-
plary facility is given in Figure 41. This facility is plant
116, and it is located within a Solvay process complex.
A listing of raw wastes produced in bicarbonate manufacture
at plant 166 is shown below. These consist of unreacted soda
ash, solid sodium bicarbonate, boiler wastes and ash from
power generation equipment. The ash is treated as a solid
waste.
Wast^e_Product Process Source kg/kkg of Product __ (lb/ton)
Average
1. Na2_C03 Slurry thickener overflow 38.0(76.0) 0-375(0-750)
2. Ash Power generation 17.9(35.8)
3. Water purif. Boiler feed water 0.3(0.6)
sludge purification
U. NaHC03_ slurry thickener overflow 10.0(20.0)
The quantity of slurry thickener overflow depends upon the oper-
ation of another plant utilizing this by-product. The overflow
is not constant, and occurs only when the sister plant mentioned
above cannot absorb the entire flow. Consequently, the value
shown above is based on an annual average, with a wide variation
in flow over the period.
Waste Treatment at Plant 166
The water usage at plant 16.6 is shown below. Most of it is used
for cooling purposes.
109
-------
RECYCLE LIQUOR
OVERFLOW
LIQUID
A
PRODUCT
TO COOLER. CURER, C05>
CLASSIFICATION , £, %
(40%)
SODIUM
SESQUICARBONATE
FEED
BACKLASH
BACK WASH
(SODIUM
SEWER
SODIUM
SESQUICARBONATE
PURGE
SEWER SUSQUICARBONATE
SEWER pURGE)
MILL
WATER
FIGURE 41
SOLVAY SODIUM BICARBONATE PROCESS FLOW DIAGRAM AT PLANT 166
-------
toP_l ant :
Lake 1,430 (0.378)
Municipal 119 (0.0315)
5,430 (1,300) Chlorinated prior to
use as cooling water
455 (109)
Cooling
Process
1,430
119
(0.378)
(0.0315)
liters/kkg ^gal/tpn
5,430 (1,300)
455 (109)
None
Treatments are carried out for the two emerging waste streams.
These streams are fed to settling ponds to remove suspended
sclids and then discharged.
Stream
Settling
Pond Over-
flow
Cooling
Water
(Discharge)
jal/ton) Treatment Disposal
Slurry
thickener
Various
heat ex-
change
devices
found
throuohour,
plant
287 (69)
5,430 (1,300)
Settling
Pond
Plant
Effluent
a)Containment Effluent
of wastes
b) Cooling water
segregation
c)Some water
recycling
d) Collection
and sampling
of wastes
Individual effluents from this plant are combined witn other sewer
effluents. Some wastes are treated in conjunction with soda ash plant
wastes. Tabulated loads are based on reasonable allocations.
The effluent from Plant 166 contains 20,000 mg/1 of dissolved solids
(mostly dissolved carbonates), amounting to 5.75 kg/kkg of product: (11.5
Ib/ton). All of the bicarbonate wastes are treated along with chlor-
alkali and soda ash wastes at the 166 facility in a common treatment
system prior to discharge. There are no net effluent loads to the
cooling water based on average daily operation. There are no organics
in the plant effluent.
Plant 166 has plans to use the weak slurry thickener overflow, which
constitutes their present major source of waste, as a source of liquid
for the product dryer scrubber and to recycle this liquid (concentrated
111
-------
with respect to sodium carbonate) back to the process. These process
changes will eliminate the discharge of process wastewaters.
GTC verification measurements on the plant intake water, cooling water,
and effluent are given in Table 6. The similarity of composition of
plant intake and cooling water discharge verifies segregation of cooling
water from process water. The process effluent measured is the effluent
of the whole plant complex and hence is not indicative of that of an
isolated bicarbonate unit.
Sodium Chloride (Solar)
Sodium chloride is produced by three methods: 1) Solar evaporation of
seawater; 2) Solution mining of natural brines; 3) Conventional mining
of rock salt.
In the solar evaporation
evaporation over a period of
saturated brine
then fed to a
leaving behind
process, sea water is concentrated by
five years in open ponds to yield a
solution. After saturation is reached, the brine is
crystallizer, wherein sodium chloride precipitates,
a concentrated brine solution (bittern) consisting of
sodium, potassium and magnesium salts. The precipitated sodium chloric!-?
is recovered for sale and the brine is then further evaporated to
recover additional sodium chloride values and is then either stored,
discharged back to salt water or further worked to recover potassium and
magnesium salts. The exemplary plant solar process is well represented
by the standard process flow diagram. Figure 13.
In the solar evaporation process, all of the wastes are present in th°
bittern solution which is presently stored at all facilities. Typical
bittern analysis for the exemplary 059 facility is given in Table 7. No
bittern is discharged from this facility. The bittern is stored and, in
the past, has been worked for recovery of other materials.
At plant 059, treatment consists of storage and further use of the
bittern materials. There is no waste discharge. The plant water usage
is:
cu m/day 1/kkg
Ty_p_e Use §oy££§ (MGD) (sal/ton) Recycle
Process Refining Well
process
Process Raw Material Bay
2,270
(0.60)
327,000
(86.4)
894
(214)
129,000
(30,900)
100%
None
As the bitterns are stored and further worked, there is no discharge.
Eventual total evaporation after further bittern use yields only solid
112
-------
TABLE 6. Plant 166 Verification Data
Parameter
Plant Intake
Bi carbonate
Cooling Water
Plant
Complex
Effluent
Measured
Flow,cu m/day No
(MGD) u
Temperature, °C
Color (Apparent)
APHA Units
Turbidity, FTU
Conducti vi ty,
mg/1 NaCl
mi cromhos/cm
Suspended Sol ids ,
mg/1
Dissolved Sol ids,
mg/1
pH
Acidity:
Total ,mg/l CaC03.
Free,mg/1 CaCOS."
Alkalinity (Total)
P,mg/l CaCO^,
T,mg/l CaC03
Hardness:
Total ,mg/l CaC03.
Calcium,mg/1 CaCOS.
Halogens:
Chlorine,mg/1
Chloride ,mg/l
Fluori de ,mg/l
Sulfate ,mg/l
Phosphates
Total ,mg/l
Ni trogen
Total , mg/1 N
Heavy Metals: Iron
mg/1 Fe
Chromate,mg/l
Cr+6
Oxygen (Di ssolved) ,
mg/1 02
t meas
red
11 .2
20
10
2000
3800
2850
7.80
0
0
0
195
1300
1250
0.1
1525
0.45
170
1 .1
0.55
0.07
0.01
4.7
Furnished
188,000
(49.5)*
27
171
1428
571
Not Measured 17,400
(4.6)
Not Measured Not Measured
270 275
30 0
1800 67,000
3400 118,000
160 206
2560 76,000
7.75 10.8
0 0
0 0
0 460
305 610
1000 45,000
950 45,000
1 .9 0
1275
0.50 1.36
130 640
1.0 0.7
0.43 1.7
0 0.48
0 0
13 4
*Furnishes cooling water to whole plant
113
-------
TABLE 7. Chemical Analysis of Bittern
Parameter*
PH
Total
Total
Total
Total
Solids
Volative Solids
Suspended Solids
Dissolved Solids
Alkalinity as CaCOa
BOD
COD
Ammonia as N
Kjeldahl Nitrogen Total
Nitrate as N
Phosphorus Total as P
Chloride
Cyanide
Fluoride
Phenols
Sulfate as S
Sulfide as S
TOC
Aluminum
Arsenic
Cadmi urn
Calcium
Chromium
Iron
Mercury
Sodi urn
Titanium
Zi nc
7.8
241550
86600
1760
239790
2800
198
6350
0.702
. 32.610
37.50
0.22
158000
0.04
74.90
0.064
21000
2
900
2.5
0.04
0.02
450
0.02
6.5
0.001
5500
0.02
0.19
* All units mg/1 unless otherwise specified.
114
-------
wastes. Sufficient land and ponding area is available at the 059
facility to store bitterns for the next 30-50 years without difficulty.
Sodium Silicate
Sodium silicate is manufactured by the reaction of soda ash or anhydrous
sodium hydroxide with silica in a furnace, followed by dissolution of
the product in water under pressure to prepare sodium silicate
solutions. In some plants, the liquid silicate solutions are then
further reacted with sodium hydroxide to manufacture metasilicates which
are then isolated by evaporation and sold. Figure 42 shows the total
system diagram for the exemplary facility at plant 172.
The raw waste loads for plant 072 are listed below. These wastes
consist mostly of sodium silicate and unreacted silica:
Avg. kg/kkg of
Waste.Products ££Ocess_Source Dry Basis_Product tlb/tonj_
Sodium Silicate Scrubbers 37 (74)
Silica Scrubbers 2.85 (5.7)
NaOH/Silicates Washdowns 0.39 (0.78)
Data on in-plant water use could not be obtained from the exemplary
plant 072. However, the water use data from another plant (134) not
exemplary because it has process water discharge is given below on the
basis of unit weight of product (dry basis) to indicate the general
level. The water intake is 2,900 liters per metric ton (710 gal/ton)
which is used as follows:
Water_Use 1/kkg (gal/ton)
Process water 1,020 (245)
Boiler blow-down. Compressor 610 (147)
cooling. Wash-down, Tank
cleaning, and misc.
Steam, Evaporation, and 1,330 (319)
other losses
At the exemplary plant all scrubber and washdown waters are sent to a
totally enclosed evaporation pond. There is no plant effluent. Since
this exemplary plant is in an area of normal rainfall and humidity for
the humid areas of the United States, the evaporation ponding technique
appears generally applicable.
Sulfuric Acid (Sulfur-Burning)
115
-------
WATER VAPOR,DUST
N
-------
Sulfuric acid is manufactured primarily by the contact process which
involves catalytic oxidation of sulfur dioxide to sulfur trioxide and
reaction of the sulfur trioxide with water to yield sulfuric acid.
Within the contact process, there are three subcategories of plants.
(1) Double absorption - paired sulfur trioxide absorption towers and
catalyst beds in series are used to maximize conversion of sulfur
dioxide so that tail gas scrubbers are not required.
(2) Single absorption - single absorption towers and catalyst beds are
used and tail gases frequently have to be scrubbed to remove sulfur
oxides; and
(3) Spend acid plants - these plants use spent sulfuric acid in place
of, or in addition to, sulfur as a raw material. While the acid
production parts of these plants are the same as those tor single
absorption, these plants are unique because of the spent, acid pyrolysis
units used to convert the waste sulfuric acid raw materials to a sulfur
dioxide feed stream. In this section, we will consider only the first
two types of plants.
Double Absorption
In the double absorption contact process, sulfur is burned to yield
sulfur dioxide which is then passed through a catalytic converter with
air to produce sulfur trioxide. The sulfur trioxide is then abosrbed in
95-97% sulfuric acid. The gases emerging from the absorber are then fed
to a second converter to oxidize the remaining sulfur dioxide to sulfur
trioxide which is then absorbed in a second absorption tower, and the
tail gases are vented to the atmosphere. Figure 43 shows a detailed
process flow sheet for plant 086, which is the exemplary plant.
At plant 086, only cooling water is discharged. In double absorption
olants, the tail gases are sufficiently depleted to sulfur oxides that
there is no need for gas scrubbers. Also, at this plant, use of
extensive maintenance and leak prevention has been employed to prevent
discharge of any product acid.
The table below shows water usage at plant 086. Most water is used for
cooling. Process water is consumed to make sulfuric acid and is not-
discharged. The only plant effluent is the cooling water used in the
heat exchangers and associated water treatment chemicals.
s_to_Plant :
(MGD}_
1/kkg (gal/tonL Comments
River
Municipal
35,200 (9.30) 55,600 (13,300) Used for cooling
only
1,020 (0.27) 1,610 (386) Used for process
steam and cooling
117
-------
oo
MUNICIPAL WATER->
SOFTENER
I
BACK WASH
TO RIVER
LEGEND:
WATER OR STREAM FLOW
PROCESS FLOW
CONDENSATE
SULFUR
JLFUR AIR
X 1
SULFUR
BURNER
FEED
WATER
HEATER
EXPORT STEAM
t
I
I
M/
WASTE
HEAT
BOILERS
BLOWDOWN
*
TO RIVER
T
MUNICIPAL WATER- ^
CONVERTER
AND
ABSORPTION
SYSTEM
STEAM
BLOWER
TURBINE
PROCESS
HEATING
RIVER WATER
ACID
COOLERS
1 1
SULFURIC
ACID
TO
RIVER
FIGURE 43
DOUBLE ABSORPTION CONTACT SULFURIC ACID PROCESS
FLOW DIAGRAM AT PLANT 086
-------
1/kkg
Cooling Fiver 35,200 (9.30) 55,600 (13,300) 0
Municipal 295 (0.078) 463 (111) 0
Process Municipal 117 (0.031) 18U (44) 0
Steam Municipal 610 (0.161) 960 (230) 0
The only effluent from this facility is once-through cooling water.
Table 8 shows GTC verification measurements for the water intake and
effluent. Comparison of these two shews no clear evidence that process
water effluent is added to ^he cooling waters.
This plant is exemplary with respect to both air emissions and lack of
sulfuric acid discharges.
Single Absorption
The single absorption process differs from that previously described
only in the arrangement of converters and absorbers. The rest of the
process is the same. For the single absorption process, the sulfur
dioxide is passed through one or more converters and then into one or
more absorbers prior to venting to the atmosphere. This arrangement is
less effective for both conversion of sulfur dioxide to sulfur trioxide
and for absorption of the sulfur trioxide into the absorber sulfuric
acid. As a result, the tail gases may have to be scrubbed, and this may
create a waterborne waste not present for double absorption plants. The
exemplary plant is plant 141.
For the single absorption sulfur-burning process, there are no wastes
from the sulfuric acid process itself. Wastes arise from the use of
water treatment chemicals. The raw wastes are iron, silicon, calcium
and magnesium salts from water treatment. This does not cover spent
acid plants based on single absorption.
Most of the cooling water used at this plant is recycled and only 5
percent emerges from the plant. This is sent to evaporation ponds, from
which there is no discharge. The water input is well water in the
quantity of 606 cu m/day (0.160 MGD) or 1,670 liters/kkg of product (400
gal/ton). This water is used as follows:
lY2§ cH-ffi/day, IMGDL 1/kkg .(gal/ton) Recycled
Cooling 560 (0.148) 1,540 (370) 95
Process 45.5 (0.012) 125 (30) 0
Sanitary Insignificant 0
119
-------
TABLE 8. Intake and Effluent Measurements at
Plant 086
Parameter* Intake Effluent
Flow cu m/day (MGD) Not Measured T1.350 (3.0)
Temperature, °C 13 26.5
Color (apparent - 40 40
APHA std.)
Turbidity (FTU) 10 15
Conductivity (as Nad) 17,500 1:8,000
Suspended Solids 10 5
pH 7.5 7.43
Acidity: Total
Free
Alkalinity: (Total) P(CaC03) 0 0
T( " ) 93 91
Hardness: Total(CaC03) 3,300 3,200
Calcium(CaCO>3) 600 590'
Halogens: Chlorine
Chloride 10,000 10,000
Fluoride
Sulfate 1,500 1,500
Phosphates (Ortho) 0.70 0.68
Nitrate, N 0.24 0.26
Heavy Metals: Iron 0.28 0.32
Chromate
Oxygen (Dissolved)
Sulfite 1 1
COD
*A11units mg/1 unless otherwise specified.
120
-------
All waterborne wastes are sent to an evaporation pond. There
is no discharge. Table 9 shows GTC verification measurements
on the intake water, the effluent going to the evaporation
pond, and the evaporation pond water, respectively.
Category 2 Chemicals
Calcium Chloride
Calcium chloride is produced by extraction from natural brines.
Some material is also recovered as a by-product of soda ash
manufacture by the Solvay process. The latter will be dis-
cussed in the soda ash section (Category 2, pages 157 ff.).
In the manufacture of calcium chloride from brines, the salrs
are solution mined and the resulting brines are first partly
evaporated to remove sodium chloride by precipitation. The
brine is further purified by addition of other materials to
remove sodium, potassium and magnesium salts by precipita-
tion and further evaporation, and is then evaporated to dry-
ness to recover calcium chloride which is packaged and sold.
Figure UU shows the detailed separation procedure used at the
exemplary plant, plant 185. Bromides and iodides are first
separated from the brines before sodium chloride recovery is
performed. There is a large degree of brine recycling to re-
move most sodium chloride values. The composition of the brine is:
Cad 2 19.3%
MgCl2 3.1*
NaCl 4.9*
KCl l.UX
Bromides 0.25%
Other minerals 0.5%
Water Balance
The raw wastes expected from calcium chloride manufacture at
plant 185 arise from blowdowns as well as from the several
partial evaporation steps used. Most of the wastes are weak
brine solutions:
121
-------
TABLE 9. In-Plant Water Streams at Plant 141
Parameter*
Flow
Temperature (°C)
Color (Apparent-APHA)
Turbidity (FTU)
Conductivity (as NaCl )
Suspended Solids
Acidity: Total
Free
Alkalinity (Total)
P
T
Hardness: Total
Cal ci urn
Hal ogens : Chi ori ne
Chi ori de
Fl uori de
Sulfate
Phosphates (Total )
Nitrogen (Total )
Heavy Metals: Iron
Chromate
Oxygen (Dissolved)
COD
Well Intake
Water
Unable to
measure
19
100
35
410
40
7.0
0
0
0
475
410
275
0
18.5
0.35
78
1.6
0.03
18
0
5.3
25
Sump to
Ponds
24.6
0
10
360
4700
8.5
0
0
0
120
250
112
0
20
0.6
340
0.64
0.18
9
0.16
5.5
575
Evaporati on
Pond
17.5
.3.5
10
790
0
7.7
0
0
0
105
500
400
0
22.5
0.77
680
0.12
0
4
0.03
7.9
70
*A11units mg/1 unless otherwise specified.
122
-------
BRINE
WELL"
SEPARATOR
IODIDES, BROMIDES AND
' MAGNESIUM TO OTHER PROCESSES
INVENTORY
COOLING
WATER „
EVAPORATOR
WASTE
• STEAM
>CONDENSATE
-^CONDENSATE
NaCI SEPARATOR
CaClg LIQUOR^
38% SOLUTION"
PROCESS_
WATER
NaCI DISSOLVER
CaCI2 (SOLUTION)
PURIFICATION
VENT TO.
EXHAUST
COOLING
WATER
TO CHLOR-ALKALI
COOLING WATER
FROM PROCESS
SCRUBBER
WASTE•
_v
EVAPORATOR
FLAKER AND DRYER
-STEAM
'CONDENSATE
COOLING
.WATER
COOLING
TOWER
WASTE
ANHYDROUS PRODUCT
FIGURE 44
CALCIUM CHLORIDE FLOW DIAGRAM
AT PLANT 185
123
-------
Avg. kg/kkg of
Waste_Products Process Source Product 1Ib/ton)
NH3 Evaporators 0.55 (1.1)
Cad2 Evaporators 29 (58)
NaCl Evaporators 0.5 (1.0)
CaCl2 Packaging 0.7 (1.4)
*Nad S KCl Brine Separation 45.5 (91)
*NaCl Secondary Brine Separation 110 (220)
*Recycled or used elsewhere.
Water Use and Treatment at Exemplary PlantAt plant 185, the waste brine
streams are passed through an activated sludge treatment to remove
organics and are then passed to a settling basin to remove suspended
matter, adjusted to neutral pH, fed into a second pond to further settle
suspended matter, and finally discharged. Future plans at the 185 plant
call for changes in the evaporators to reduce calcium chloride
discharoes and eliminate ammonia from the discharges. More recycling of
spent brines is also planned. Table 10 gives a detailed breakdown of
current water usage at plant 185.
Table 10A lists the river intake and effluent compositions at plant 185.
The effluent consists mostly of weak brine solutions (neutral pH).
These discharges are expected to be reduced in the near future.
Hydrogen Peroxide (Organic Process)
Hydrogen peroxide is manufactured by three different processes: (1) An
electrolytic process; (2) An organic process involving the oxidation and
reduction of anthraquinone; and (3) A by-product of acetone manufacture
from isopropyl alcohol. In this study, we considered only the first two
processes.
In the organic process, anthraquinone (or an alkylanthraquinone) in an
organic solvent is catalytically hydrogenated to yield a
hydroanthraquinone. This material is then oxidized with oxygen or air
back to anthraquinone, with hydrogen peroxide being produced as a by-
product. The peroxide is water-extracted from the reaction medium, and
the organic solvent and anthraquinone are recycled. The recovered
peroxide is then purified and shipped. Figure 45 shows a specific
flowsheet for the exemplary facility, plant 069, including part of the
waste abatement system.
124
-------
TABLE 10. Plant 185 Water Flows
Inputs
Type
River (+ 44%)
Lake
cu m/day (MGD) liters/kkg (gal/ton)
31 ,100 (8.208)
545 (0.144)
62,700 (15,000)
1 ,100 (263)
Water Usage
Type cu m/day (MGD) liters/kkg (gal/ton) % Recycled
Cooli ng
Process
Washdown
Washout
58,500 (15.5)
164,000 (43.2)
2,180 (0.576)
680 (0.180)
118,000 (28,300)
330 (79)
4,390 (1 ,052)
1 ,370 (329)
46
0
0
10
TABLE 10A,
Parameter*
Composition of
of Plant 185
Intake and Effluent Stream
Flow, cu m/day (MGD)
Total Suspended Solids
Total Dissolved Solids
BOD
COD
pH
Turbidity (FTU)
Color (ALPH Units)
Conductivity (NaCl )
Hardness (Ca)
Sulfate
Ni trate
Ammonia
Organic Nitrogen
Iron
Copper
Chromate
Manganese
Zinc
Total Alkalinity (CaC03)
Intake
Plant
Data
31 ,600
(8.35)
42
353
3
GTC
Measuremen
**
8
293
-
t
Effluent Stream No. 1
0.1
0.05
0.1
160
170
Plant
Data
31 ,600
(8.35)
2,693
1 .1
8.3
5.3
20
476
200
110
0.2
0.1
0.2
0.4
8.3
0
70
520
179
36
0.29
0.60
-
0.30
6.7-8.0
18.2
60
5,390
700
312
0.2
2.0
2.7
1 .0
0.1
0.1
0.85
67
GTC
Measurement
**
29
309
9.1
25
80
340
169
36
20
8.8
0.09
235
* mg/1unless otherwise specified
**measurement not possible due to physical constraints of location
Note: Above data not split samples; plant data furnished separately,
prior to sampling for verification.
125,
-------
ORGANIC REACTION MEDIUM
S3
ORGANIC
SOLVENT
HYDROGEN
\
N >
OXYGEN
t 1
HYDROGENATION
\
^
2
OXIDATION
/ \
?
EXTRACTION
AND
PURIFICATION
SHIPPING
^
^
WATER
TREATMENT
\
H202
/ v y
ORGANICS
H202
H202
H2S04
DITCH
FIGURE 45
HYDROGEN PEROXIDE PROCESS DIAGRAM FOR PLANT 069
-------
Pro ducts
Sulfuric Acid
Trace Organics
Hydrogen Peroxide
Process_Source
Ion Exchange Units
Contact Cooling
Purification Washings
Operation Avg. Range
ka/kkg_llb/ton]_
12.5-15 (25-30)
0.17-0.35 (0.34-0.70)
20-25 (40-50)
The process runs continuously except for shut-down approximately 10 days-
per year. Total discharge will normally be no higher during start-up
and shut-down periods than under operation at capacity.
Treatment at Plant 069
water usage at plant 069 is described by the data given below:
Water_Inp_ut_to_Plant. Well water at 312 cu m/kkg of pro-
duct (74,500 gal/ton) having the following composition:
H^ejr. Usage
Type
Cooling
Process
Total Solids
Carbon Dioxide
Total Hardness
Fe
Cu
?n
Sulfate
Alkalinity (CaCO3)
cu_m/kkc[ (gal/ton)
365 (87,200)
16 (3,800)
110-125 mg/1
30-60 mg/1
80-100 mg/1
1-3 mg/1
0.03-0.06 mg/1
0.02 mg/1
2-7 mg/1
70-110 mg/1
% Recycled
25% recycled
35% of remainder-
used twice
Most of the water is used for cooling, and a relatively large fraction
of this water is recycled.
The data below describes the treatment of the waste stream emerging from
the peroxide plant. Peroxide is decomposed by iron filings, and organic
solvent losses are minimized by a skimming operation:
Waste_Strearn Source
Process Process
Effluent
cu m/kkg
(gal/tgnL
294
(70,200)
Final
Treatment
1. Peroxide reacted
with iron filings
2. Skimmers used to
trap organics for
recovery
River
127
-------
3. Waste sulfuric acid
is collected and
discharged at a
controlled rate
W. Solids (alumina 6
carbon) are hauled
to landfill
The effectiveness of the treatments in use is:
Qualitative Waste Reduction
Method Rating
Reduction Generally satisfactory 80% reduction of peroxide
to water and oxygen
Skimming Generally satisfactory 60-70% of organics
recovered
The effluent composition after treatment is given in Table 11. The
wastes consist of unreacted peroxide and a small amount of organics and
sulfates.
Sodium Metal
Sodium is manufactured by electrolysis cf molten sodium chloride in a
Downs electrolytic cell. After salt purification to remove calcium and
magnesium salts and sulfates, the sodium chloride is dried and fed to
the cell, where calcium chloride is added to give a low-melting CaC12-
NaCl eutectic, which is then electrolyzed. Sodium is formed at one
electrode, collected as a liquid, filtered and sold. The chlorine
liberated at the other -electrode is first dried with sulfuric acid and
then purified, compressed, liquified and sold. Figure 46 shows the
process in use and waste treatment facilities at the exemplary facility,
plant 096.
Paw Waste Loads
There is no waste during operation of an individual cell for the molten
salt electrolysis step in the Downs cell process. The cells are run in
banks, and individual cells are cleaned out and refilled after the
electrolyte is depleted. All of the wastes arise from this cleaning and
refilling of individual cells.
The wastes produced by sodium manufacture at plant 096 are shown below.
Several of the expected wastes are not present. This is due to the
reuse of materials in other parts of the facility to make other
products, for example, the sulfuric acid used in drying the chlorine.
128
-------
TABLE 11. Plant 069 Process Water Effluent After Treatment
Parameter*
Total Suspended Solids
Total Dissolved Solids
BOD
COD
pH
Temperature
T.O.C.
Hydrogen Peroxide
Turbidity (Jackson
Units)
Color (APHA Units)
Acidity (Free)
Acidity (Total)
Alkalinity (Total)
Hardness (Total )
Chloride
Sulfate
Iron
Copper
Fl ow
Plant Data
Average Range
15-20
310-330
6-7
40
30°C
25
0
0
6-9
5-15
60-80
20-20
40-50
150-195
90-105
40-75
2-3.5
,08-0.09
Verification Sample
GTC
Measurement
25,000
cu m/day
(6.6 MGD)
(7
9
98
50
6.4
27°C
12
50
61
92
5
43
1 .6
26,000
cu m/day
1 MGD)
Plant 069
Measurement
9
117
33
6.6
37.8
25
10
46
7
52
0.26
129
-------
PROCESS
V
EQUIPMENT REPAIR
WATER, Fe
I I
UJ UJ
zo:
o
0
0
t 1 1 1
PRODUCT PURIFICATION
al
->CI/PRODUCT
g
o
p
6*
-10
oz
FIGURE 46
WASTE TREATMENT ON DOWNS CELL AT PLANT 096
-------
Waste Products
Procgss Source kg/kkg of Product lib/ton)
NaCl Process
Misc. Alkaline Salts Process
Ca (OC1) 2_ Chlorine Recovery
Fe Coolinq Tower
50-65 (100-130)
25-35 (50-70)
U5-75 (90-150)
0.065-0.095 (0.13-0.19)
The process docs not normally shut down. The discharges result trom the
replacement of cells.
At the exemplary plant, cooling tower blowdowns and residual chlorir~
from tail gas scrubbers are discharged without treatment. The stream
containing calcium hypochlorite wastes is not discharged but is used to
tre>at cyanide wastes. Cooling water is discharged without treatment and
tank wash and runoff water are first ponded to settle out suspended
materials and then discharged.
The water input to the plant is well water in the amount of 2,730 cu
m/day or 46,300 1/kkg of product (11,100 gal/ton), having an impurity
conten4- of:
110-125 mg/1
30-60 mg/1
80-100 mg/1
1-3 mg/1
0.02-0.06 mg/1
0.02 mg/1
To-^al Solids
C02.
Hardness (as Ca)
Fe
Cu
Zn
Sulfat.e
Alkalinity (CaCO3)
2-7 mg/1
70-100 mg/1
The water use within the plant is as follows:
Use Flow Amount
Cooling
Process
29,100 cu m/day
(7.7 MGD)
530 cu m/day
(0.1U .MGD)
497,000 1/kkg
(119,000 gal/ton)
9,000 1/kkg
(2,150 gal/ton)
The 2% recycled process water is used in the calcium hypochloiite
absorber. Table 12 lists the various plant waste streams and their
compositions.
These stream effluents consist mostly of dissolved sodium chloride and
other chlorides. Table 13 shows the results of analyses of simultaneous
samples from three of the waste streams (those corresponding to streams
2, 3, and U of Table 12) performed by plant 096 and GTC. Good agreement
between the results was generally obtained.
131
-------
TABLE 12. Plant 096 Effluent
Stream No. Stream No. Stream No. Stream No.
Parameter* 1** 2*** 3**** 4*****
Flow, cu m/day 409(0.108) 133(0.035) 1,780(0.470) 409(0.108)
(MGD)
TSS 30-50 50-70 5-10
IDS 400-600 - 300-400
BOD -
COD -
pH 6.5-7.5 10.5-12.0 6.7-7.5
Fe 2 1-2 2-3
Chloride 100-150 10,000-30,000 50-100 13,000
Chlorine - 4,000-6,000 20-100
Sulfate - - 25-50
Total Hardness - - 180-225
Phosphate 0.2
Turbidity(FTU) 25-30 40-60 125
Color(APHA) 15 15 15
Acidity(Free) 20-30 20-30
Alkalinity - 4,000-6,000
(Total)
Hardness(Ca) - 25,000-30,000
*A11 units mg/1 unless otherwise specified.
**Cooling Tower Slowdown, C12 Residual.
***Calcium hypochlorite used to treat cyanide wastes in another
process.
****Cooling water.
*****Runoff, excess calcium hypochlorite, tank washup.
Note: There is also 2,270 liters/day (600 GPD) used sulfuric
acid sent for use elsewhere in the complex and not dis-
charged into surface streams.
132
-------
TABLE 13. Plant 096 Effluent
Parameter*
Flow, cu m/day (MGD)
Plant
GTC
Temperature, °C
Plant
GTC
Color(True),
APHA Units
Plant
GTC
Turbidity,
Jackson Units
Plant
GTC
Suspended Solids
Plant
GTC
Dissolved Solids
Plant
GTC
PH
Plant
GTC
Acidity(Free)
Plant
GTC
Alkalinity(CaCOS)
Plant
GTC
Chlorine
Plant
GTC
Chloride
Plant
GTC
Sulfate
Plant
GTC •
Fe
Plant
GTC
Stream No.
2
-
133(0.035)
-
21.5
15
300
26
82
39
39
574
479
6.5
6.55
19.5
-
-
48
0
0
121
125
-
-
0.33
0.22
Stream No.
3
-
1,590(0.42)
-
22
15
30
25
10
6
11
355
266
6.45
6.44
37.5
-
-
57
0.6
0.2
92
90
26
10
0.69
2.7
Stream No
4
-
-
-
20
15
260
58
45
137
90
_
35,800
11.9
11.9
-
_
_
4,500
64,000
2,400
17,800
26,500
_
_
0.92
0.7
*mg/l unless otherwise specified.
133
-------
This facility is exemplary in having good pH and suspended solids
control and reuse of some wastes, but there are large amounts of
chlorides being discharged which could,be recycled for process reuse.
Sodium Chloride (Solution Mining of Brines)
Sodium chloride is produced by three methods: 1. Solar evaporation of
seawater; 2. Solution mining of natural brines; mined mineral is
frequently sold as-is to users. In some cases the rock salt recovered
is purified, but in thes.e cases, the methods used are the same as those
employed with solution-mined brines. In this report, we discuss the
first two methods of sodium chloride production, as contacts with the
industry have revealed there are no waterborne wastes normally
associated with the conventional mining operations. Processes were
discussed previously.
Saturated brine for the production of evaporated salt is usually
obtained by pumping water into an underground salt deposit and removing
the saturated salt solution from an adjacent interconnected well, or
from the same well by means of an annular pipe.' Besides sodium
chloride, the trine will contain some calcium sulfate, calcium chloride,
magnesium chloride, and lesser amounts of other materials including iron
salts and sulfides.
The chemical treatment given to brines varies from plant to plant
depending on the impurities present. Typically, the brine is first
aerated to remove hydrogen sulfide and, in many cases, small amounts of
chlorine are added to complete sulfide removal and oxidize all iron
salts present to the ferric state. The brine is then pumped to settling
tanks where it is treated with soda ash and caustic soda to remove most
of the calcium, magnesium and iron present as insoluble salts. After
clarification to remove these insolubles, the brine is sent to multiple-
effect evaporators. As water is removed, salt crystals form and are
removed as a slurry. After screening to remove lumps, the slurry is
washed with fresh brine to remove fine crystals of calcium sulfate from
the mother liquor to the slurry. These solids are returned to the
evaporator. The calcium sulfate concentration in the evaporator
eventually builds up to the point where it must be removed by "boiling
out" the evaporators.
The washed slurry is filtered, the mother liquor is returned to the
evaporators, and the salt crystals from the filter are dried and
screened. Salt thus produced from a typical brine will be of 99.8
percent purity or greater. Some plants do not treat the raw brine, but
control the calcium and magnesium impurities by watching the
concentrations in the evaporators and bleeding off sufficient brine to
maintain predetermined levels. By such methods, salt of better than
99.5 percent purity can be made. In either case, the final screening of
the dried salt yields various grades depending on particle size. The
134
-------
exemplary facility at plant 030 is similar to the standard flow diagram,
Figure 22, shown in Section IV.
A detailed list of the raw wastes and their process sources is shown.
below. These include wastes from the multiple evaporators and dryers,
sludges from basic purification, as well as water treatment chemicals
used for the cooling water:
w§ste_Products ££oce§s_Source Ayg^. kg/kkg of Product (Ib/ton)
NaOH Boiler Blowdown 0.0055 (0.011)
Na3P04 " " 0.0015 (0.003)
Na2SiO3 " " 0.0025 (0.005)
Na2SO3 " " 0.0015 (0.003)
NaCl & CaSO4 Purge from multiple 0.045 (0.090)
evaporator
NaCl Evaporator 0.04 (0.08)
NaCl Barometric condenser 1.1 (2.2)
NaCl Miscellaneous sources
Brine sludges Brine purification 91 kkg/year
(100 ton/year)
The brine sludges are returned to the brine wells for settling
and disposal.
Water Usage and Treatment
Well water for brine field use is taken into the plant at a
rate of 2,240 liters/kkg of product (536 gal/ton). Lake
water for cooling and other uses is drawn into the plant at
a rate of 48,000 liters/kkg (11,400 gal/ton).
Use Flow Recygle
Cooling (barometric 41,700 liters/kkg none
(condensers) (10,000 gal/ton)
Other (dust collection 6,400 liters/kkg 90*+
pumps) (1,540 gal/ton)
Treatments of the effluent streams are as follows:
Stream_No. Source Treatment
1 Condenser Discharge To Lake
2 Storm Drain To Lake
3 Tunnel Line (Lake Water) To Lake
4 Ash Lime Discharge Recycled
The storm drain flow cited above was 3,790 1/kkg of product (910
gal/ton) on the average.
135
-------
The plant effluent streams #1 and #2 after treatment were portrayed by
the plant personnel as consisting solely of streams containing 100 mg/1
chloride at a pH of 8.2. Chloride concentration at the plant intake was
given as 70-80 mg/1, with a pH of 8.2. Table 1U shows GTC verification
measurements on the plant intake and condenser discharge (stream #1)
effluent. Only a small amount of chloride has been added to the water
used. The chloride content and pH as stated are verified within a
reasonable margin.
Sod ium_Sulfi t e
Sodium sulfite is manufactured ty reaction of sulfur dioxide with soda
ash. The crude sulfite formed in this reaction is then purified,
filtered to remove ir.solubles from the purification step, crystallized,
dried and shipped. A process diagram for the exemplary facility, plan-:
168, is given in Figure 47.
A listing of the raw wastes produced from sodium sulfite production is
given below. These consist of sul fides from the purification step and a
solution produced by periodic vessel cleanouts containing sulfite and
sulfate.
Waste_Products P£°2<|ss__Source kg/kkg of Product (lb/;ton)
Average Range
Metal sulfides Filter wash 0.755 0.19-1.44
(1.51) (0.38-2.88)
Na2SO3/Na2SO4 Dryer ejector
solution
Na2SO3/Na2SC4_ Process cleanout
solution
Cleanouts of various process vessels produce shock loads up to 9.1 kkg
(10 tons) of sodium sulfite and sulfate (dry basis). Cleanouts are
conducted 3-6 times per year. For this, separate tanks are used for
surge capacity with bleed into the treatment unit over a 5-10 day
period.
Approximately 244 cu m/kkg of product (57,600 gal/ton) of river water
and 290 to 630 1/kkg (70 to 150 gal/ton) of municipal water are taken
into the plant. The stated analysis and GTC verification of the river
intake is:
136
-------
TABLE 14. GTC Verification Measurements at Plant 030
Parameter*
Flow, cu m/day (MGD)
Temperature, °C
Color, APHA Std.
Turbidity(FTU)
Conductivity(NaCl)
Suspended Solids
PH
Acidity: Total
Free
Alkalinity (Total)
Hardness: Total
Calcium
Halogens: Chloride
Sulfate
Phosphates
Nitrogen
Heavy Metals: Iron
Oxygen (Dissolved)
COD
Intake
37,900(10)
13
40
10
225
0
8.0
0
0
0
139
171
128
65
13
0.07
0.17
0.24
55
Condenser
Discharge
37,900(10.0)
22.5-23.0
40
15
320
0
8.1
0
0
0
140
189
147
120
37
0.1
0.17
0.23
2.8
50
kmg/~\ unless otherwise specified.
137
-------
SMALL RECYCLE
S02 NOgC
1 X
REACTOR
COOLER
7 I
RIVER WATER
NaOH -
CuCl£ -
NaHS-
TREATMENT
CITY
WATER"
FILTRATION
CONDENSATE
WATER
r
CRYSTALLIZATION
A
CENTRIFUGE
CITY_
WATER
DRYING
PRODUCT
Na2S03
OXIDATION
i
i
M/
HOLDING
FILTRATION
i r
i i
\y V
SOLIDS CLEAN
WATER
FIGURE 47
SODIUM SULFITE PROCESS FLOW DIAGRAM
AT PLANT 168
138
-------
Conc en t r at ion
GTC
Parameter
pH
Suspended
Solids
BOD
Iron
Copper
Chromium
?inc
Nickel
Lead
Dissolved
Solids
Average
(6.80)
28
14.8
2.6
0.02
O.C1
0.49
0.01
0.02
Range
5.68-7.12
10-45
1.4-38.5
1.5-4.9
0.01-0.02
0.01-0.02
0.08-1.84
0.01-0.02
0.01-0.07
Measurement (mg/11
7.00
10
0.9
0.1
168
The in-plant use of the water intake is as follows:
Use lit££S/]s3S3 (<-L§_l/i°.D) Percent Recycle
Indirect cooling
Process (conden-
sate)
Dryer, Ejector,
Filter Wash
Approx. 244,000(57,600)
Approx. 170(40)
290 to 630
(70 to 150)
0
0
The principal waste streams operating on a continuous basis consist of
flows from the dryer ejector and filter washing operations. These
waters are treated by aeration and filtration prior to discharge.
Vessel washouts are also subjected to the aeration and filtration
procedure. The performance experience of oxidation and filtration
treatment processes at this plant is:
Method
Oxidation
Filtration
Qualitative
Rating
Excellent
Excellent
Waste Reduction Accomplished
94% oxidation of sulfite to sulfare
98% suspended solids removal
Compositions of the process effluents streams after treatments are given
below. The waste stream after aeration treatment and the same stream
after it has been subjected to a final filtration prior to discharge are
shown. The cooling stream, which consists of untreated river water, has
the same composition as measured at the intake. The GTC measurements
for verification of the process effluents and cooling water are given in
Tables 15 and 16, respectively.
139
-------
TABLE 15. Measurements of Plant 168 Process Waste
Streams Before and After Treatment
Parameter*
Flow
Temperature, °C(°F)
Col or(Apparent) APHA Std.
Turbidity, FTU
Total Dissolved Solids
Total Suspended Solids
PH
Alkalinity (Total) P
T
Hydrogen Sulfide
Sulfite
COD
Before**
(Batch Process)
76.7(170)
500
500
88,200
780
11.0
9,000
24,000
0
60,000
8,000
After
(Batch Process)
76.7(170)
500
380
93,900
2,010
11.2
4
,500
,800
0
170
250
*mg/l unless otherwise specified.
**This sample was collected from the full oxidation tank just
before the waste treatment process was begun. This was nec-
essary because the waste lines to the tank are not accessible
for sampling and the only outlet valve is on the tank itself.
140
-------
TABLE 16. Plant 168 Cooling Water Measurements
Parameter* '- Intake Effluent
Temperature, °C 17 21
Color(Apparent) APHA Std. 95 65
Turbidity, FTU 25 15
Conductivity, as Nad 130 120
Suspended Solids 10 8
pH 7.00 7.08
Acidity: Total 0 0
Free 0 0
Alkalinity (Total) P 0 0
T 40 40
Hardness: Total 73 76
Calcium 50 51
Halogens: Chlorine 24 24
Sulfate 53 55
Phosphates 0.72 0.66
Nitrate 0.33 0.32
Heavy Metals: Iron 0.86 0.78
Hydrogen Sulfide 0 0
Sodium Sulfite 3 4
*mg/l unless otherwise specified.
141
-------
After Aeration After Final Filtration
Parameter Ave. Range Ave. Range
Total Suspended 0.22% 0.07-0.41% 97 mg/1 3-240 mg/1
Solids
Total Dissolved 5.7% 4.64-6.95% 5.7% 4.64-6.9%
Solids
BOD5 56.8 mg/1 46-71 mg/1 56.8 mg/1 46-71 mg/1
COD 118 mg/1 64-161 mg/1 118 mg/1 64-161 mg/1
pH 9.8 9.7-9.9 9.8 9.7-9.9
Temperature 65°C - 43°C 38-49°C
Soda Ash
Soda ash is produced by two methods; mining and the Solvay Procesb. As
there are no water-borne wastes associated with the mining operations,
our detailed treatment of soda ash will concern the Solvay Process. Raw
sodium chloride brine is purified to remove calcium and magnesium
compounds and is reacted with ammonia and carbon dioxide produced from
limestone calcination to yield crude sodium bicarbonate which is
recovered from the solutions by filtration. The.bicarbonate is calcined
to yield soda ash and ^he spent brine-ammonia solution is reacted with
slaked lime and distilled to recover ammonia values for process recycle.
The calcium chloride formed as a by-product during the" distillation is
either discharged as a waste or recovered by evaporation. Figure 48
shows a process flowsheet for the facility at plant 166. .Although all
Solvay Process plants have high dissolved solids effluents, this plant
is unusual in that it recovers a significant amount of an otherwise
wasted by-product. Since the market for calcium chloride will not
absorb the by-product generated from such recovery from all Solvay
plants, this plant cannot be considered to be exemplary on this basis.
The information from it is given here to document such by-product
recovery and because it employs generally good processing practices for
this industry.
The raw waste loads for the 166 facility consist of brine purification
muds unreacted sodium chloride and the calcium chloride by-product
as follows:
142
-------
(jj
SODA AJI .. M|X Aflu < I.II.IN u. umi.
i • REACTION „„.„
RAW ^ BRINE
8RNE * RESERVOIR
-^ lANub SCRUBS E
DRYCRS
^ MILK OF L
CRUDE
BICARBO'JATE
OF SODA
<—
STEAMS
RECOVERED AMMONIA GAS
1
TO
SETTLINGS-
PONDS
1 T0
I CdCU PLANTS —
FILTER
LIQUOR DISTILLER \W
V \'
LIME HE.T
DISTILLER * HEAT
BRINE PURIFICATION MUDS
LIMESTONE »
COAL >
WATER
1
\l/ V
SCRUBBER
~«0% IUBE
CO, r— WtriJ?
T -L ^TEM
^S > COMPRESSORS
IME 1
1 LUBE WATER
RECYCLE PURO
A
TO WASTE
COLLECTION VARIOUS WEAK
CENTER LIOUOFK AND
CONBENSATE
A (ALL FREE NH,)
STE STEAM I 3
•i/ V
,,,„„ WEAK
DISTILLER
\, VAPOR
LIME
^
SLAKERS
w $ a?
1 |<5 |1
ffl1!
^_
STRAY LIQUOR
/T» /T> yT. /\
1 S JO UJ
o-^5 o §
§§§ 1 5
§ s = *
'15-1
HEAT TRAP
l
SPRAYS ETC.
FIGURE 48
SOLVAY SODA ASH PROCESS FLOW DIAGRAM AT PLANT 166
-------
Waste Products
Process Source
of Soda Ash (Ib/ton)
1* CaC03
2. Na2CO3
3. CaS03~*
4. Nad"
5. CaCl2
6. Na2SO4
~i. Fe(OHf3_
8. Mg (OH) 2
9. CaO (inactive)
10. NaOH
11. Si02
12. CaO (active)
13. NH3
14. H2S
15. Ash £ Cinders
DS, E, P
B
DS
DS, B
DS
B
B
DS, B, P
DS, B
B
DS, B
DS
DS
DS
DS = Distillation, E = Brine, P = Power
Water Use in Plant 166
Input s_to_Plant :
River
Lake
Municipal
Water Flows:
84.5
0.3
31
510.5
1090
0.8
0.1
"U8.5
109.5
0.05
58.5
24
0.15
0.02
40
(169)
(0.6)
(62)
(1021)
(2180)
(1,6)
(0.2)
(97)
(219)
(0.1)
(117)
(48)
(0.3)
(0.04)
(80)
3,650 (875)
4,680 (1,120)
2,030 (486)
Comments
Sent to Power Section for
boiler feed water
Treated prior to use with
chlorine
Majority is sent to Power
Section for boiler feedwater
Cooling
Process
Sanitary
Boiler Feed
52,100 (12,500)
4.5 (1.1)
Est. 74-149
(18-36)
5,420 (1,300)
Recycled
3-9
0
The maximum process water is about 149 1/kkg (36 gal/ton), but the
average is only 4.5 1/kkg (1.1 gal/ton).
144
-------
Most, of the water use is for cooling purposes and little stream
recycling is employed. Treatment methods in use are:
Stream
Source
Treatment
Disposal
Cooling water Various heat a. Internal recycle Disposal to
effluent
Settling pond
effluent
exchangers
throughout
plant
Distiller
wastes
Segregation of
waste
c. Collection and
containment of
wastes
Settling out sus-
pended solids with
coagulation and
precipitation of
metals and other
chemicals
cooling water
sewer system
Discharge to
source of
cooling water
Individual effluents from this plant are combined with other effluents.
Treatment consists of use of settling ponds and some pH con
trol prior to discharge. The performance of this treatment is detailed
below:
Method
Evaporation of
distiller waste
Settling Ponds
Qualitative
Rating
Good
Excellent
Waste Reduction
Accomplished
Reduces Cad by 21*
NaCl by 4%
Suspended solids reduced
by 99% +
In addition, two other methods of treatment are used or planned:
(1) part of the wastes may be used for municipal waste
treatment.
(2) part of the raw distiller waste stream is diverted to
a small plant for calcium chloride recovery. About
21% of the calcium chloride in the raw waste is re-
covered on this sidestream.
The plant effluent after treatment contains about 100,000 mg/i dissolved
solids (mostly NaCl and CaCl2) in the process waste stream and is also
fairly high in suspended solids. This type of effluent is typical of a
Solvay process plant. The only exemplary feature of the 166 facility
lies in its partial recovery and reuse of calcium chloride wastes.
Calcium Chloride Recovery
145
-------
The flow diagram for the calcium chloride recovery process at plant 166
is shown in Figure 49. The waste stream is first cycled through a
number of partial evaporation and filtration steps to concentrate the
waste solutions. After this, further partial evaporation is used to
selectively remove the sodium chloride from solution and then total
evaporation is used to recover calcium chloride from the remaining
solution.
Table 17 shows the raw wastes produced in this recovery operation and
some other data. The principal waste is a contaminated «sodium chloride
co-product which is discarded, as well as some calcium chloride from
condensates and spills. Water use for this recovery process is:
A. Water Inputs to Plant
Tyge 1/kkg of 100% CaCl2 Jgal/ton) Comments
River 3,910 (938) Steam generation
Lake 118,500 (28,400) Cooling
Municipal 434 (104) Steam generation
B. Water Usage
J.y_E§ liters/kkg^of^10Q% CaCl2 (gal/ton) Comments
Cooling 118,500 (28,400) None
Process 3,R50 (923)
The present recovery unit reduces the effluent calcium chloride by about
21%. This is because of the limited market for calcium chloride.
According to the manufacturer, if more of the material could be
marketed, more would be recovered. Thus, the major problem with soda
ash wastes lies in finding a use or disposal for the by-product calcium
chloride. An evaporation process for its recovery, as can be seen from
this discussion, is already operative. This recovery step, as it is now
practiced, also reduces the sodium chloride effluent of the Solvay
process by 4 percent.
Table 18 shows the GTC verification measurements on the water intake,
the calcium chloride cooling water, the final effluent and the soda ash
cooling water.
Category 3 Chemicals
Mercury Cell Process Chlor-Alkali (Chlorine, Sodium Hydroxide, and
Potassium Hydroxide)
146
-------
TABLE 17. Calcium Chloride Recovery Process
A. Raw Materials for Product
1. Soda ash distiller waste
2. Chlorine
3. Carbon dioxide 40% C02
4. Captive steam and power
B. Raw Waste Loads
Waste Products
1. Ash and cinders
2. Water purification
sludge
3. NaCl co-product
4. CaC12
Process Source
Steam and power
Steam
Evaporation
Condensates and
spills
kg/kkg (Ib/ton)
of Product*
42.5(85)
0.75(1.5)
235(470)
35-50(70-100)
C. Comments
Ratio of CaCl2 to NaCl available in distiller waste is
approximately 1.4. Market demand at this location is
at a ratio of 10.6 to 1.
*Product is 100% calcium chloride.
147
-------
TABLE 18. GTC Verification Measurements at Plant 166
Parameter*
Flow, cu m/day
Temperature, °C
Color (Apparent)
APHA Units
Turbidity, FTU
Conductivity,
micromhos/cm
Suspended Solids
pH
Acidity: Total
Free
Alkalinity (Total) P
T
Hardness: Total
Calcium
Halogens : Chlorine
Chloride
Fluoride
Sulfate
Phosphates (Total)
Nitrogen (Total)
Heavy Metals: Iron
Chromate
Oxygen (Dissolved)
COD
Water
Intake
Not
Measured
11.2
20
10
2000 (NaCl)
3800
5
7.80
0 CaC03
0 "
0 "
195 "
1300"
1250"
0.1
1525
0.45
170
1.1
0.55
0.07
0.01
4.7
175
CaC12
Cooling
Water
Not
Measured
23.8
35
15
; 4000
7500
10
7.95
0
0
0
190
1400
1350
0.6
2600
0.55
170
1.2
0.58
0.18
0
7.7
~"
Final
Effluent
17,400
..
275
0
67,000
118,000
170
10.8
0
0
460
610
45,000
45,000
0
50,000
1.36
640
0.7
1.7
0.48
0
4
~
Soda Ash
Cooling
Water
Not ;
Measured
ii
110
? -•• 5
21,000
4,400
30
7.8
0
0
. 0
240
1,270
1,120
1.7
1,350
0.6
190
1.6
0.48
0.12
0
10
~
*mg/l unless otherwise specified.
148
-------
CLARIFIED LIQUOR -
NOTE.'
• OCCURS DURING
OPERATIONAL
UPSETS
LP STEAM —
CONDENSATE TO BOILER HOUSE<-
MILL
WATER
MILL WATER
TO SEWER
1 t
BAROMETRIC
FILTRATE
1
PRIMARY
CENTRIFUGE
-------
Caustic and chlorine are produced from salt or potassium chloride raw
materials in the mercury cell process, depending on whether caustic soda
or caustic potash is to be produced. ' The raw material is dissolved and
purified by addition of barium carbonate, soda ash, and lime to remove
magnesium and calcium salts and sulfates prior to electrolysis. The
insolubles formed on addition of the treatment chemicals are tiltered
from the brine. The brine is then fed to the mercury cell, wherein
chlorine is liberated at one electrode and a sodium-mercury amalgam is
formed at the other.
The chlorine formed is cooled, dried in a sulfuric acid stream, purified
to remove chlorinated organics, compressed and sold. The mercury-sodium
amalgam also formed during electrolysis is sent to a "denuder" where it
is treated with water to decompose the amalgam. Sodium hydroxide and
hydrogen are formed in the reaction. The mercury liberated is returned
to the electrolysis cells. The hydrogen is cooled, scrubbed to remove
traces of mercury, compressed and sold.
The sodium hydroxide formed at the denuders is filtered, concentrated,
and sold. Waste brines emerging from the electrolysis cells are
concentrated and recycled.
Two exemplary facilities, plants 130 and 144, and one qualified
exemplary facility, plant 098, have been selected and studied in detail.
Plant 130 produces potassium hydroxide and plants 144 and 098 produce
sodium hydroxide. Plant 098 is considered as an exemplary plant with
the gualification that it is located outside of the United States; it is
included because its mercury recovery system is of special note. The
process flow diagram for plant 130 is shown in Figure 50.
Raw waste loads for this process are presented in Table 19, which gives
overall figures based on twenty-one facilities, plus partial data as
furnished from plants 098 and 130. The chief raw wastes include
purification muds (CaCO3, Mg(OH)2 and BaSO4) from brine purification,
some spent brine materials from caustic recovery, and condensates from
chlorine and hydrogen compressions. The sulfuric acid used to dry the
chlorine is not a waste in plant 130 as it is recovered for sale.
In the caustic potash plant, plant 130, the brine muds and potassium
chloride make up the bulk of the primary waste. A small amount of
copper sulfate catalyst is also wasted. This catalyst is used in
treatment of waste chlorine. Specifically, the chlorine is reacted with
excess sodium hydroxide in the presence of copper sulfate to produce
sodium chloride, water and oxygen. The sodium chloride so produced is
sent to the waste treatment facilities.
150
-------
TABLE 19. Raw Waste Loads from Mercury Cell Process
(All Amounts in kg/kkq of Chlorine)*
Based on 21 Facilities
Purification
muds, CaCO3
6 Mg (OH) 2
NaOH
NaCl
KCl
H2SO4
Chlorinated
Mean
16.5
13.5
211
0
16
0.7
Hydro-carbons**
Na2SO4 15.5
C12
(as CaOCl2)
Filter aids
Mercury
Carbon,
graphite
CuSO4
11
0.85
0.15
20. 3
0
Range
0.5-35
0.5-32
15-500
-
0-50
0-1.5
0-63
0-75
0-5
0.02-0.28
0.35-340
Plant 098
7.25
0
11.3
1.83
0.0018
0
0.004
Plant_130
Mean
7.5
HO
50
0
6.8-7.9
35-45
45-54
*can be converted to Ib/ton of product by multiplication by 2.0,
**depends markedly on grade of chlorine produced.
151
-------
KOH
PH
ADJUST
DEPLETED BRINE
FROM CniS AT
pH 2-2.5
CCI WATER Kj,C03 ADJU
^ w \y ^ ^/
INLET BOX END BOX
VENT TO VENT TO
ATMOSPHERE NoOH SCRUBBER
SATURATOR
PURIFIER
i
BRINE FILTER
SLUDGE TO
ABATEMENT
Ul
2K-Hg + Clz
ELEPTROLYSIS AMALGAM
CI2 TO LIQU1FACTION
DEPLETED BRINE TO SATURATION ANP PURIFICATION
2KOH
SLUDGE SALES
TO KOH
ABATEMENT
SYSTEM
OVERFLOW
TO
ABATEMENT
SYSTEM
DEMINERALIZEO WATER
MJ> TO USERS;
(I),FUEL IN
(2.) OTHER PLANT USES
FIGURE 50
MERCURY CELL FLOW DIAGRAM (KOH) AT PLANT I30
-------
At plant 144, the wastes emerging from chlor-alkali manufacture are sent
to a series of two settling ponds, with the exception of those from the
cell building, which are sent to a mercury treatment unit first. The
wastes from chlorine drying, brine preparation, salt saturation and
caustic loading are sent directly to the two settling ponds described
above, where suspended solids are removed and the pH adjusted prior to
discharge. Two emergency ponds are in parallel with these two pen-is and
wastes can be diverted to them for special treatment if needed.
Mercury-containing wastes from the cell building are first treated prior
to being sent to the central waste treatment system. The effectiveness
of treatment based on six months of data (129 days of measurements) is,
in summary:
Mercury Concentration to Mercury Concentration Average Removal
Average 44.3 0.43 99.0
Maximum values 1920.0 15.0
Minimum values 0.48 0.01
153
-------
Approximately 99 percent removal of mercury is achieved with the mercury
losses from the facility being kept to about 0.0045-0.0237 kg/day (0.01-
0.05 Ib/day) for the most part. Figure 51 gives a histogram of the
mercury discharges on a daily total quantity basis. The mean value of
this discharge* parameter is 0.0178 kg/day (0.03882 Ib/day) or 0.000070
kg/kkg of chlorine (0.000140 Ib/ton of chlorine). Ninety-one percent of
the measurements fell below twice these mean values.
At plant 098 several of the streams are completely recycled to minimize
brine wastes. Treatment of mercury-containing streams makes use of
sodium sulfide to precipitate mercury and mercury sulfides. These
materials are filtered from the streams, recovered as solids and treated
with sodium hypochlorite to recover mercury (as chloride). The leached
solids can then be safely discarded and the mercury chloride-containing
solutions can be used for brine makeup and returned to the cells where
the mercury chloride is decomposed to elemental mercury for reuse.
The mercury effluent and chlorine treatment effectiveness at plant 098
are as follows:
Method
Mercury Recover
Chlorine
Neutralization System
Hydrogen Peroxide
Treatment of
liquid effluent
Qualitative
Patina*
Excellent
Excellent
Good
Waste Reduction
Accomplighed_
97% recovery of mercury
100% removal of chlorine
from waste gas stream
100% removal of available
chlorine
*As rated by plant personnel.
The mercury discharged and recovered from the sulfide treatment system
over a two month period in 1972 from this plant averaged 0.0108 kg/day
(0.0237 pounds) per day or 0.000069 kg/kkg (0.000138 Ib/ton) of
chlorine. Analysis of the data for the two month period showed that the
average mercury recovery was 258 kg (568 pounds) per day or 7.5 kg/kkg
(15.0 Ib/ton of chlorine. At the plant 130 mercury cell facility, brine
filter sludges, potassium hydroxide recovery wastes and other waste
streams are fed into a common treatment system, wherein the wastes are
treated with sodium hydrosulfide and flocculants. The insoluble mercury
products from treatment are removed by settling and filtration and the
wastes are then discharged. The mercury content of the wastes is
recovered by distillation from the recovered sludges. The mercury
treatment system is shown in Figure 52.
Table 20 summarizes the mercury effluents from plant 130 as a result of
treatment over a one-year period. The mean mercury effluent level of
0.0073 kg/day (0.016 Ib/day corresponds to a value of 0.000057 kg/kkg of
chlorine (0.000114 Ib/ton ton of chlorine), remarkably similar to the
154-
-------
TABLE 20. Monthly Mercury Abatement System Discharge
During 1972 at Plant 130
Month
Average
Volume
Discharge
cu_ m_(ga !]_/_ da_y_
Av.
123 (32,516)
Total Hg
Discharge
Jan
Feb
Mar
Apr
May
Jun
Jul
Auo
SQp
CC +
Nov
Dec
144
118
02
112
115
134
124
137
131
129
126
118
(37
(31
(24
(29
(30
(35
(32
p6
(34
(34
(33
(31
f
i
r
r
i
i
t
»
i
r
r
t
916)
0?0)
195)
616)
339)
277)
709)
169)
4^5)
024)
33^)
135)
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
369
327
198
184
318
214
225
302
127
133
176
144
(0.
(0.
(0.
(0.
(0.
(0.
(0.
(0.
(0.
(0.
(0.
(0.
813)
719)
435)
404)
700)
471)
494)
665)
280)
293)
377)
251)
Average
Daily Hg
Discharge
kg^lb) /day
0.012 (0.
0.011 (0.
0.0064 (0.
0.0059 (0.
010 (0.
0068 (0.
0073(0.
0096 (0.
0041(0.
0041 (0,
0.0055 (0.
0.0036 (0.
026)
024)
014)
013)
023)
015)
016)
021)
009)
009)
012)
008)
0.224 (0.492) 0.0073(0.016)
Average
mcg/1
Hg
82
92
69
53
91
51
59
72
31
33
43
31
59
Statistical Summary: Mercury Abatement System Jan-Aug 1972 -
Total of 244 Days
Mean
Range, Max.
Standard Deviation
of Values
Daily Mercury
Discharge,
0.0086 (0.019)
0.0545 (0.120)
0.0077 (0.017)
0.0182 (0.040)
Daily Volume
Discharge,
cu_m (gal^/day
122 (32,164)
292 (63,945)
40 (10,492)
173 (45,594)
155
-------
CO
o
o
<
UJ
O 5
I-
LJ
UJ
a.
0.01
0.02 0.03
MERCURY DISCHARGE (KG PER DAY)
0.04
0.05
RGURE 51
HISTOGRAM OF MERCURY DISCHARGES FROM PLANT 144
-------
BRINE
FILTER
SLUDGE
ACID SULFIDE
KOH
FILTER
SLUDGE
4>
->
CELL ROOM
WASHINGS,
Hs CONDENSATE,
^g CLEANUP
OPERATION.
DECHLORINATED
BRINE
CONDENSATE, ETC.
FEED
TANK
TREATERS
FILTER
FEED
TANK
FILTER
PRESS
FILTRATE
HOLD
TANK
/Sl
DRUMS
n
I LAB I
•ANALYSIS :-
| A.A. I
I I
AREA 3 OUTFALL
I. ADJUST TO pH 7
2. ADD SULFIDE I
3. ADD FLOCCULANT
4. SETTLE
5. DECANT
RECOVERED
MERCURY
HgS RECOVERY
FIGURE 52
MERCURY ABATEMENT SYSTEM AT PLANT 130
-------
0.000069 kg/kkg (0.000138 Ib/ton) calculated for the 098 plant and.
0.000070 kg/kkg (0.000140 Ib/ton) for the 144 mercury cell plant.
the
The general characteristics of the 098 plant discharge are listed below.
The seawater cooling water stream is mixed with the process water
effluent prior to discharge, hence the high TDS:
Total Suspended Solids, mg/1
Total Dissolved Solids, mg/1
PH
Temperature, °C (°F)
Hydrogen Peroxide, mq/1
Sodium Sulfide, mg/1
Free Chlorine, mg/1
Mercury, mmg
Average
7.1
12 (54)
0
0
5-10
20,000-25,000 (seawater)
6.7-8.5
10-19 (50-66)
0-1.0
0-0.5
Max. 0.08
Max. 8.0
Tables 21 and 22 give the plant 130 effluent stream data and GTC
verification data. Tables 23 and 24 give the plant 144 intake and
effluent streams data and GTC verification data.
Diaphragm Cell Chlor-Alkali Process (Chlorine/Sodium Hydroxide)
The plant 057 facility described in this section is part of an
integrated complex making use of a considerable amount of recycling and
reuse technology. The discussion below demonstrates that this facility
comes fairly close to the "zero discharge" goal.
158
-------
TABLE 21. Plant. 130 Effluent. Data*
Outfall Outfall Outfall
£1 . 12 !!!*_ Intake
Flow, cu m/day 9,U60(2.5) 13,300(3.5) 42,400(11.2)
(MGD)
^otal Suspended 5
Solids
nil P-ll 8-9 8-9
Color (APHA Units) b
Conductivity, umhoc- - 267
Hardness, (To-.a]) - - UOO 134
(CaCO3_)
Chloride - - 1252 z^
Fr^e Chlorine 0 0
Fluoride - - 1 1
Phosphates (as P) - - - 0.1
Nitrate (as N) - 1.92 1.92
Iron - - 1.2 1.0
Cooper - - - 0.01
Chromium - - 0.01 0.01
Manganes^ - - -
0.01
Vanadium -
Arsenic - 0.28
M.^rcury, mcu/1 - - 1.2 1
Lead - - 0.1 0.1
Sulfat^ - - 39 18
Turbidity - 16
*Data supplied by Plant 130, mg/1 unless otherwise specified.
**Main outfall, outfalls 1 & 2 feed into 3. This waste stream
contains potassium carbonate manufacturing effluent also.
159
-------
TABLE 22. Measurements of the Effluents
From Plant 130
Parameter*
Flow, cu m/day
(MGD)
Temp., °C
Color, Apparent,
APHA Units
Turbidity, FTU
Conductivity,
mhos/cm
Suspended Solids,
pH
Alkalinity (Total)
P (CaCO3)
T (CaCOS)
Hardness, (Total)
(CaCO3) mg/1
Calcium (CaCO3)
Chlorine
Chloride
Fluoride
Sulfate
Phosphates (Total)
Nitrogen (Total)
Iron
Dissolved oxygen
Mercury, mcg/1
Hg Cell
Piver Chlorine Major
(Intake) Li3ue.!tcti2!}** Abatement** Outfall**
Not
Measured
2.0
60
23
230
70
7.8
0
97
145
115
0
35
0
45
0.38
1.55
0.19
***
5
8,540(2.25) 16,700(4.28) 42,000(11.1)
11.95
60
19
240
210
11.9
40
180
60
25
0.2
47.5
0
44
0.4
0.45
0.5
8.3
5
10.1
180
55
320
75
9.4
30
135
140
110
0.3
60
0
41
0.42
0.13
0.7
7.6
5
8.5
150
50
370
210
10.5
25
200
65
35
0
48.5
0
40
0.37
0.38
0.4
8.5
*mg/l unless otherwise specified.
**Corresponds to outfalls #1, 2 and 3 respectively on Table 21,
***Unable to determine at temperature below 5°C.
160
-------
TABLE 23. Plant 144 Intake Water
GTC
Parameter* ElfLD.t_Data** Measurement.
Temperature, °C 8-24 19
Colcr, Apparent, APHA Units - 175
Turbidity, FTU - 50
Conductivity, mhos/en; 75 55
Suspended Solids 10 10
Dissolved Solids 65
oH 6.6 6.7
Acidity: To^al - 0 CaCQ.3
^ree - 0 "
Alkalinity (Total) P - 0 "
T 18 16 "
Hardness: Total - 15 "
Calcium - 5 "
Halcqf-ns: Chlorine - 0.18
Chloride - 15
Fluoride - 0.1
Rulfate - 8
Phosphates (Total) - 0.34
Heavy Metals: Iron - 0.48
Chromate (Cr + 6) - 0.02
Oxyaer. (Dissolved) - 12
COO 15 10
*mq/l unless otherwis^ specified.
**Data from Corns of Engineers permit application, approximately
two years prior to verification sampling.
161
-------
TABLE 24. Plant 144 Effluent Data
Parameter*
Flow, cu m/day (MGD)
Temperature, °C
Color, Apparent, APHA Units
Turbidity, FTU
Conductivity, mhos/cm
Suspended Solids
Dissolved Solids
PH
Acidity: Total
Free
Alkalinity (Total) P
T
Hardness:#Total
Calcium
Halogens: Chlorine
Chloride
Fluoride
Sulfate
Phosphates (Total)
Heavy Metals: Iron
Chromate (Cr+6)
Oxygen (Dissolved)
COD
Mercury, mcg/1
Plant Data**
5,300 (1.9)
32-38
1,525
0
1,455
7.0
60
8
3
GTC
Measurement:
8,360 (3.0)
33
30
10
2,000
0
1,777
7.5
0 CaCO3
0 '•
0 '•
14 '•
20 "
10 "
0
1020
0.5
107
0.18
0.42
0.02
10
5
5
*mg/l unless otherwise specified.
**Data from Corps of Engineers permit application, approximately
two years prior to verification sampling.
162
-------
sodium
are first purified by addition of
and sodium hydroxide in the amount;
Sodium chloride brine . t ^
carbonate, flocculating agents and sodium hydroxide in the amounts
required to precipitate all the magnesium and calcium contents of tht=
brine. The brine is then filtered to remove the precipitated materials
and el^ctrolyzed in a diaphragm cell. Chlorine, termed at one
electrode, is collected, cooled, dried with sulfuric acid, then
and shipped. At the other electrode.
purified,
is
compressed,
liquefied
(JUI.J-1 .L ~*-i , l^vjlllj.j.L'^osc:'^, _L J-v^u^r j_ j_c*-l dl ivu oilx^-'^-'^va . rl i- uuc \J L-ut= ±. ^: _L — v^ i.. i. \j •-,( ~ ,
sodium hydroxide is formed and hydrogen is liberated. The hydrogen is
cooled, purified, compressed and sold; and the sodium hydroxide ;.orn'.eu.
Ourinq
cnloride
collected
- — - — - » i_ - — - - - w - i. , j .
along with unreacted brine, is evaporated to 50% conceritratio
the partial evaporation, most of the unreacted sodium
precipitates from the solution, which is then filtered. The
sodium chloride is recycled to the process, and the sodium hydroxide
solutions are further evaporated to yield solid products.
Figure 53 shows the flow diagram of a
caustic soda plant at plant 057. A new 2080 kkg (2500 ton) p'-r :.lay
chlorine-caustic soda plant also exists in this facility. Tne -o^.i-um
from these two plants is concentrated in another
^his function is illustrated in Figure 54. All
(all parts of plant 057) will be dibcn-pe-^
1810 kkg/day (2000 ton) chlor
hydroxide product
portion of pl^nt 057.
three of these facilities
There are no brine wastes from plant 057 and several of the oth^r waste
streams are diverted for other uses in the complex. This stream
diversion and maximal raw material utilization has served to minimize
the wastes to be treated. The raw wastes from the newer plant
1. NaOCl
2. NaHCO3
3. Chlorinated
Organics
4. Brine Sludge
5. Spent Sulfuric
Acid
6. Chromates
7. Suspended Solids
Gas Scrubber
Gas Scrubber
Liquefaction
Brine Treatment
Chlorine Drying
Cooling Tower
Cooling Tower
1.13 (2.26)
(Startup and shutdown)
2.49 (4.58)
(Wastes are ponded for recycle)
0.35 (0.70)
10.5 (21)
1.0 (2.0)
The raw wastes from the old plant are:
Waste Product
1. Weak Caustic
2. Spent Sulfuric
Acid
Process Source
Cells
Chlorine Drying
0.000363 (0.00072b)
0.0333 (0.0666)
Average kg/kkv-j of
Chlorine (Ib/ton)
66.25 (12.5)
4.05 (8.1)
163
-------
RIVER WATER
BRINE WELL
NaCI
NaOH
RIVER WATER
1
COOLER
H2
H2 DISTRIBUTION
AMMONIA PLANT
H2S04-
RIVER WATER
SEA WATER
No CIO
"L
TAIL GAS
SCRUBBER
SATURATOR
MIXER
NOTE;
• WASTE STREAMS
CLARIFIER
SETTLING PONDS
CELLS
COOLER
DRYER
\/
COMPRESSOR
SOLIDS (LANDFILL)
•TRENCH NaOH STARTUP
>AND SHUTDOWN
>NaOH STORAGE
AND DISTRIBUTION
RIVER WATER AND SEA WATER
'CHLORINATED WATER
if STORAGE DISTRIBUTION
r 60% H2S04
WATER
INTERCOOLER
-TAIL GAS
SEA WATER
LIQUEFACTION
TANK CAR
LOADING
LIQUID CHLORINE
\/
STORAGE
COOLING SEA WATER
CHLORINATED HYDROCARBONS
DISTRIBUTION
t
EVAPORATOR
FIGURE 53
DIAPHRAGM CELL CHLOR -ALKALI PROCESS
AT PLANT 057
-------
NaOH 8NaCJ_
FROM CELLS
\
/
EVAPORATORS
X.
S
FILTERS
~N
s
COOLING
EQUIPMENT
^s
S
FILTERS
x,
s
PURIFIERS
(Ti
U1
WASTE
ENTRAPMENT
OTHER SLURRY
PLANT TO BRINE
USE TREATING
SYSTEM
SALT
TO
RECOVERY
\
PRODUCT
FIGURE 54
SODIUM HYDROXIDE CONCENTRATION FACILITY AT PLANT 057
-------
3. NaOCl
4. Carbonate Sludge
(CaCO3)
5. Chlorinated
Hydroca rbon s
Tail Gas Scrubber
Brine Treating
Chlorine Purification
The raw wastes from the caustic plant are:
Waste Products
1. NaOH
2. NaCl
3. NaOH
4. NaCl
Prgeess Source
Entrainment
Fntrainment
Filter Wash
Filter Wash
7.50 (15.0)
12.25 (24.5)
0.70 (1.4)
Average kg/kkg of
_Product Qb/ton]_
4.4 (8.8)
5.1 (10.2)
17.6 (35.2)
20.3 (40.6)
Many of the chlor-alkali waste streams, including brine wastes, are
either recycled or put to use elsewhere in the complex. This section
discusses treatment of those streams which are discharged.
The newer chlor-alkali plant takes in 2,720 cu m/day (0.72 MGD) oi river
water for cooling makeup and process water, as well as 54 cu m/day
(0.0144 MGD) of well water for potable use. About 98.5% of rhe total
cooling water flow of 109,000 cu m/day (28.8 MGD) is recycled, and 90%
of the process water flow of 6040 cu m/day (1.6 MGD) is recycled. Of
the potable water intake, 10? is recycled.
The waste treatment within this newer plant is:
Stream No./gource
I/Gas Scrubber
2/Spent Sulfuric
Acid
3/Chlorine lique-
faction
4/Brine Treating
5/Cooling Tower
Slowdown
Flow, I/day
IGPDI
Treatment
Method
409,000 Sunlight decompo-
(108,000) sition of NaOCl
2,890
(765)
492
(130)
327,000
(86,400)
75,700
(20,000)
Other plant use
Incineration
Solids to land-
fill
None
Final
Disposal
To plant
waste water
system
Used
Brine recycled
To plant
waste water
system
Waste chlorine in the tail gas is reduced by 80% in an absorption
process, and the remaining chlorine is removed by scrubbing. These two
processes are used in series to attain complete removal of chlorine from
166
-------
-he rail aas. Ponding is stated to he 100"? effective in removal of
solids, due to recycle of brine.
Future treatment plans which will further reduce the wastes to the point
where the facility will approach the zero discharge goal are:
Estimated
Installation Estimated
Method Time Performance
1. Chlorinated hydrocarbon 2 years 100%
waste burner
2. Catalytic conversion 1 year 100%
of scrubber effluent
•••o remove sodium
hyoochlorite
3. Neutralization of 1 year 100%
scrubber effluent
-o remove sodium
carbonate
ht the older chlor-alkali facility in plant 057, river water inii^Ke is
10,'J70 cu m/d^y (2.76 MGD) and seawater intake is 57,200 cu m/day (1S.1U
MOD). The coolina water flow is 61,000 cu m/day (16.13 MGD) , which is
all non-contact except for the water chlorination step. Process war^-r
flow is 6.530 cu m/day (1.726 MGD) , which is mainly as bri^co. Oth-r
nrocess water uses are compression cooling, hydrogen cooling, cnlorir^
cooling and absorption. There is less recycling of water here tnan in
the newer plant. The effluent stream which is not recycled arises from
•^he tail gas scrubber, which has a flow of 133,000 I/per day (3^,000
GPD) or 141 1/kkq (37.2 aal/ton) based on chlorine product. Tnis i=
disposed of completely in the plant waste system. It contains sodium
hypcchlorite. The disposal of this material will be eliminated by mid-
summer 1973, ?.nd the tail gas will be used to manufacture hydrochloric
acid product, thus eliminating a waste stream. When this happens, the
older process should be close to a nondischarge system,
Th<= water intake to the caustic plant is:
cu_m/day [MGD)
river water 1,890 (0.50)
seawater 90,900 (2U.O)
well water 57 (0.015)
The river water is treated; the well water is not. The in-
plant water flows are:
cu_m/day_ (MGD) % Recycled
Forced Draft Cooling 6,540 (1.73) 95
Process 1,300 (0.344) 0
Washdowns 265 (0.07) 0
Entrainment Seawater 90,000 (24.0) 0
167
-------
The only effluent to be treated is 4.4 kg/kkg (8.8 Ib/ton) of sodium
hydroxide and 5.1 kg/kkg (10.2 Ib/ton) of sodium chloride in a 90,900 cu
m/day seawater waste stream (the entrained system). This system is
presently discharged without treatment. Future plans call for it to be
neutralized prior to discharge. Chloride values entrained in this
stream are considered to be too low to be worthwhile for other plant
usage. These three facilities are being improved to further reduce
discharges. When all of the improvements cited in this sec-cion have
been completed, this whole chlor-alkali facility should approach the
zero discharge goal.
The effluents from the newer chlor-alkali facility, the older facility
and the sodium hydroxide plant are shown below. The relative amoun-i-s of
waste produced are quite small and will be reduced in the future.
Parameter
Total Dissolved
Solids
Total Suspended
Solids
BOD
COD
pH
Temperature, °C
Chromate
Older_Plant:
Dissolved Solids
AlJ$a_l:L_P!ant:
NaOH
NaCl
Stream No.
Average Concentration, mg/1
). 1 2 _3 4 5 _
1200 820
18,330
(mostly
chlorides)
14
0
0
7.8
-
—
0
0
1
38 Ambient
22,500 256
0
0
-
31
-
0
0
11.0
Ambient
-
0
0
7.0
32
10
103,090 (chlorides, hypochlorites)
25
28.9 (added to seawater)
Hydrogen Peroxide (Electrolytic) Hydrogen peroxide is manufactured by
three different processes: (1) An electrolytic process; (2) An organic
process involving the oxidation and reduction of anthraquinone; and (3)
As a byproduct of acetone manufacture from isopropyl alcohol. In this
168
-------
study, only the first two processes are considered. Th<
was discussed under Category 2.
organic process
In the electrolytic process, a solution of ammonium Disulfate in
electrolyzed, hydrogen is liberated at the cathodes of the cells used,
and ammonium persulfate is formed at the anode. The persulfate is then
hydrolyzed to yield ammonium bisulfate and. hydrogen peroxide which is
senarated by fractionation from the solution. The ammonium bisulfate
solution is then recycled, and the peroxide is recovered for sale. Th-:
only waste is a stream of condensate from the fractionation conciens-r.
Figure 55 shows the process waste treatment system at: the exemplary
plant, plant 100.
Table 25 lists the raw wastes from peroxide manufacture at plant 100.
These consist of ammonium bisulfate losses, ion exchange losses, boiler
blowdowns and some cyanide wastes from the special batteries use-! in
electrolysis.
Plant Water Use
Plant water intake and use are as follows:
water
Municipal
Well
Flow, cu m/day
IMGD]
7.2 (0.0019)
Amount, 1/kkg
41,600 (11.0)
601
3,U80,000
Use
Drinking,
Washing,
Sanitary
76 cu m/day
(0.002 MGD)
demineralized
for process
water, rest
used as cooxiag
Of the 76 cu m/day of process water, 31% is used in the product.
Recycle flow of process water is 132 cu m/day and recycle flow of steam
is 305 cu m/day (liquid basis). About 26.5 cu m/day is boiler blowdown.
None of the cooling water is recycled.
169.
-------
TABLE 25,
Raw Waste Loads at Plant 100
Waste
Product
1. Blue prus-
siate sludge
2. Gray sludge
3. Ion Exchange
sludge
4. H2S04
5. (NHU)2SOU
6. Water flow
7. HC1
8. NaOH
9. Steam
condensate
Process
Source_
Purif.
Battery
rebuild
Deionizer
regen.
Plant solu-
tion loss
Plant solu-
tion loss
Cooling
Deionizer
regen.
Deionizer
regen.
Boiler
blowdown
kg/kkg of Peroxide lib/ton)
Operation Startup Shutdown
0.18(0.36)
(5 times
per year)
0.0018(0.0036)
0. 012(0. 02U)
2000-2900
(UOOO-58000)
1.3(2.6)
0.33(0.66)
581 (1162)
No significant diff-
erence during start-
up 6 shutdown periods.
Plant runs contin-
uously; shuts down
once per year.
Comments: H2_SOU and (NHUJ^SOU are used to replenish plant solution.
Na4Fe (CN) 6 is converted to (NHU) UFe(CN)6 through ion ex-
change (yellow solution) .
NH4SCN is oxidized in the batteries and is used for
better current efficiency.
HCl and NaOH are used for regeneration of demineralized
water ion exchange resins.
170
-------
WATER SUPPLY
DEEP WELLS
SLUDGE
SETTLING
TANK
SLUDGE
SETTLING
TANK
_y
COOLING WATER
FOR HEAT
EXCHANGERS
CONDENSERS
(INTERMITTENT DISCHARGE ONCE A WEEK)
WATER
DEIONIZERS
YELLOW
SOLUTION
DEIONIZER
REGENERATION EFFLUENTS
(INTERMITTENT DISCHARGE]
_y
BOILERS
CONTINOUS BOILER
BLOW-DOWN
8
o
UJ
o
I
o
-------
Waste Treatment
Table 26 lists the various plant effluent streams, their
sources, values and treatments. Treatments consist of ion
exchange for pH control and recovery of some process mater-
ials, and recovery of platinum in the waste streams. After
this, wastes are discharged.
Performance information on the pH control and ion exchange
technology used for waste abatement in this plant is:
Method
1. pH Control
2. Process change
3. Monitorina
Plant Effluent
Qualitative
Rating
Good
Excellent
Good
Waste Feduction
Accomplished
99+%
CN- load reduced 98% -
Additional concentration to
discharge stream less than
0.01 mg/1
Reduces unknown discharges
and allows quick operation
response.
Table 27 lists the compositions of the various effluent streams after
treatment. These streams are then mixed prior to discharge. Table 28
shows a GTC analysis of the intake water and final effluent after
mixing. Only very small amounts of materials are introduced into the
waters used, and cyanides in the effluent are negligible.
Chromate Manufacture (Sodium Dichromate and Sodium Sulfate
Sodium dichromate is prepared by calcining a mixture of chrome ore
(FeO.Cr2O3) , soda ash and lime, followed by water leaching and
acidification of the soluble chromates. The insoluble residue from the
leaching operation is recycled to leach out additional material.
172
-------
TABLE 26,
Effluent Treatment Data for Plant 100
Water Streams
Stream No.
I/day
1. Low Exchange
Reqenerant
2. Flue Prussiate
Supernatant
(filter back-
wash)
1. Yellow Solution Ion Exchange
U. Boiler Blowdown Boilers
Source
Demineralizer 3,790(1,000)
Filters 568(150)*
1/kkg
(gal/ton)^
317(76)
47.6(11.4)
568(150)* 47.6(iI.M
26,500(7,000) 2,210(530)
B
Treatments
Stream No.
Final
Disposal
Treatment Method
Anion and cation regener- Plant effluent
ants are mixed to control
pH and slowly released.
Settled for platinum recov- Plant effluent.
ery, siphoned and
filtered**.
Backwash recycled to pro- Plant effluent
cess and regenerant is
discharged.
Dilution Plant effluent
*These operations are batch carried out an average of once
per week. ,
**Sludges recovered here are sent to refiners for recovery
of platinum values.
173
-------
TABLE 27. Composition of Plant 100 Effluent Streams
After Treatment
Total Suspended
Solids
Total Dissolved
Solids
BOD
COD
PH
Temperature, °C
Orqanics
Conductivity
micromhos/cm
Alkalinity
Free Cyanide
Phosphate
Chloride
Stream Stream
1856 as CaCO3
equiv. during
regeneration
Comparable to
raw water
Same as raw --
water
Same as raw
water
6.5-8.5 H
17 18
0
7160
Stream Stream
0
200-UOO U0,000 1,000
7
18
400
0
30
20-30 (as
NaCl)
*all units mg/1 unless otherwise specified.
174
-------
TABLE 28. Plant 100 Water Intake and Final Effluenr.
Verification Measurements
Parameter* Wel.l_Water Outfall
Conductivity, 120 (as NaCl) 120 (as Nc.Cl)
micromhos/cm 2^0
Color 0 0
Turbidity 0 0
SS 00
oH 6.8R 7.0U
Sulphate 18 21
Nitrate 3.3 2.3
Phosphate 0.35 0.36
Iron 0-02 0.01
Chloride 6.5 7.5
Hardness (Ca) 65 70
Total Hardness 95 90
*mg/l unless otherwise specified.
175
-------
During the first acidification step, the chromate solution pH is
adjusted to precipitate calcium salts. Further acidification converts
it to the dichromate and a subsequent evaporation step crystallizes
sodium sulfate (salt cake) out of the liquor. The sulfate is then dried
and sold. The solutions remaining after sulfate removal are further
evaporated to recover sodium dichromate. Chromic acid is produced from
sodium dichromate by reaction with sulfuric acid. Sodium bisulfate is a
by-product. Figure 56 shows a detailed flowsheet tor the exemplary
facility at. plant 184.
Plant 184 manufactures only the sodium dichromate and chromic acid.
However, some other chromate plants, none of which are exemplary, do
convert part of their chromic acid products to potassium dichromete.
All of this latter material is made in plants that produce oth^r
chromates but the plant 184 facility is, to our knowledge, the only
exemplary chromate facility, based on effluent quality.
The raw waste loads expected from the manufacture of sodium dichromate
and its by-product sodium sulfate are given below. The bulk of the
waste originates from the undiges#ed portions of the ores used. These
materials are mostly solid wastes. The wastes arising from spills and
washdowns contain most of the hexavalent chromium. The wastes from
water treatment and boiler blowdowns are principally dissolved sulfates
and chlorides. The manufacture of chromic acid contributes no addition-
al wastes.
Waste_Product Process Source Product (Ib/ton)
me
1. Chromate wastes Residues 900(1800)
(Materials not
digested in H2S04)
2. Washdowns* — 0.75(1.5) 0.5-1(1-2)
spills, etc.
3. Blowdown Boilers and — 0.5-1(1-2)
cooling
towers
*Includes contributions from the chromic acid unit.
Water intake to this facility consists of river water and well water in
the following amounts based on sodium dichromate product: 12,700 1/kkg
(3,030 gal/ton) and 1,840 1/kkg (440 gal/ton) respectively. The boiler
feed comes from the river water feed and is softened prior to use. The
well water is all filtered, softened and chlorinated.
176
-------
BALL MILLS
1
Ii lur PULVERIZED
LIME CHROME ORE SODA
1 A
i
| BLOW TANKS
>
| MIX FEED TANKS
1 KILNS
| LEACH TANKS
ASH
-
RECYCLE
1
| CLASSIFIER | s| FILTERS | S
,
SULFURIC ACID 5 ACID FIER
•) TANKS
| FILTER |
SODA ASH ^ • PRECIPITATOR
| FILTER
^
SULFURICACID > ^ RER
•
| EVAPORATOR |
v
EVAPORATOR
N
| FILTER
SULFURIC ACID
1
CHROMIC SODIUM
ACID BICHROMATE
REACTOR LIQUOR
1 ( FILTER
f
MELTERS | 5J FLAKERS
SODIUM CMBOU
BISIII FATT
C ACID
PICKLE
LIQUOR
,
WASTE
—5 TREATMENT ( S
REACTORS
«—
•
RESIDUE
DRYER
OOA ASH
1
WASTE LAGOONS > EFFLUENT TO RIVER
HSULFATE
CENTRIFUGES
DRYER
SODIUM
SULFATE
v
•
CRYSTALLIZER
,
-•
CENTRIFUGE
DRYER
COOLER
SODIUM
BICHROMATE
CRYSTALS
FIGURE 56
CHROMATE MANUFACTURING FACILITY
AT PLANT 184
177
-------
Water_Use:
1/kkg of sodium
Tyjae dichromate (gal/toa) % Recycled
Cooling 275,000 (66,000) 98.2
Products and 5,400 ( 1,300) 0
Evaporation
Waste Treatment 8,860 ( 2,120) 0
Sanitary 255 ( 60) 0 :
Waste Treatment :
Waste waters are treated with pickle liquor to effect reduction of
chromates present and then all effluent waters are lagooned to settle
out suspended solids. This treatment removes 99% of the hexavalent
chromium and the discharge contains 0.01 mg/1. The lagoon discharges to
a nearby river when full.
Chromate waste control in this plant is excellent. All rainwater,
washdowns, spills and minor leaks in the part of the plant which handles
hexavalent chromium are captured in the area's sumps and used in th^
process. Storage facilities are provided to contain a heavy rain and
return the water either to the process or to treatment. Separate
rainwater drainage is provided for areas not handling hexavalent
chromium. Sewers are continuously monitored. Even cooling tower and
boiler blowdowns go through the process waste treatment, as do all waste
sludges. A batch system is used in the treatment process. Each batch
is treated and analyzed before release to the lagoon.
Effluent
Data on the effluent from this exemplary chromate treatment facility are
presented below:
Average Bange
Flow, liters/kkg (gal/ton) 8,860 (2,120)
Total Suspended Solids, mg/1 1U 1-2U
Total Dissolved Solids, mg/1 10,000 5,000 - 13,000
(mostly chlorides)
pH 7.2 6.0-8.5
Cr+3, mg/1 0.1U 0.01 - 0.31
(mostly in form of suspended solids)
Cr+6, mg/1 «0.01
The chromium content has been reduced to negligible values. However,
the amount of sodium chloride being discharged is significant. Based on
the porous nature of the present lagoon walls and the , high dissolved
178
-------
solids content discharged into the river, this plant is considered
exemplary only from the standpoint of chromates control and treatment.
Table 29 gives a more detailed presentation for the river intake and
plant effluent from this facility. The composition of river water taken
near the plant and the plant effluent determined on two separate
occasions are shown as a range of values. These data were furnished by
the plant.
Tables 30 and 31 present data obtained by the GTC mobile sampling
laboratory for this facility. Table 30 shows an analysis of river water
drawn adjacent to the plant. Table 31 shows the compositions of waste
stream before and after passage through the pickle liquor treatment
unit. During sampling at this facility, it was not possible to obtain
an effluent sample because treatment ponds were being switched over and
the newer pond was not yet filled to overflow level. Since the first
pond reguired several months to fill, overflow level in the new pond was
not reached in time for analysis during this study.
179
-------
TABLE 29. Intake and Effluent Composition at Plant 184
Parameter
Total Solids
Organic Solids
Mineral Solids
Alkalinity as CaCO3_ (methyl-orange)
Alkalinity (phenolphthalein) ^
Free Carbon Dioxide
Total Hardness (as CaCO3)
Total Hardness (grains per gallon)
PH
Analysis of Mineral Solids:
Silica (SiO2)
Iron Oxide (Fe203)
Alumina (A12O3J
Lime (CaO)
Magnesia (MgO)
Sulphate (SO3J
Chloride (Cl)
Soda (Na20)
Manganese (Mn)
Fluoride (F)
Biochemical Oxygen Demand (BOD5)
Color (Pt-Co)
Chromium (Cr)
Tannin
*mg/l unless otherwise specified
**None found
River
Water
79
45
34
2.0
0.0
1.6
15
0.88
6.4
2.6
0.4
0.8
5.6
2.0
6.8
8.9
5.7
0.0
0.0
Plant
Effluent
330-334
93-104
230-232
0.0
0.0
1.0-17.0
209.3-238.7
12.2-12.8
7.4-8.4
5.0-6.0
0.1-0.3
0.0
114.4-115.5
0.8-5.0
3.4
1.3-1.8
8.2-10.4
0.0
0.0
less than 5
130
T
2.6
**
**
180
-------
TABLE 30. Analysis of River Water at the
Exemplary Chromate Facility 184
Parameter
Color, APHA Units
Turbidity, FTU
Conductivity
Suspended Solids
PH
Alkalinity (Total)
Hardness: (Total)
(Calcium)
Halogens: Chloride
Sulfate
Phosphate
Nitrate
Heavy Metals: Iron
Chromium (Cr+6)
Measurements (mg/1 unless
otherwise_sjoecified
270
5
35 NaCl eq.
5
6.59
phen-O/Total-20 (as CaC03)
23 (as CaC03)
15
11
0
0. 38
0.13 (as N)
1.5
0*
*less +:han 20 mcg/1
181
-------
TABLE 31. Analysis of Waste Treatment Streams
at Plant 184
Parameter
Flow
Temperature,
color
°c
Conductivity
Dissolved Solids
Suspended Solids
PH
Alkalinity (Total)
Hardness: Total
Calcium
Halogens: Chloride
Sulfate
Phosphate
Nitrate
Heavy Metals:
Chromium (Cr+6)
Iron
Oxygen (Dissolved)
Before Treatment
Batch volume -
28,700 liters
49
500 (supernatant
liquid)
5000 NaCl
10,700
170,000
10 (straight);
9.3 (dilution)
phen-O/total-1000
(as CaCO3)
600 (as CaCO3)
520 (as CaC03)
310
3,900
0.7
9.8 (as N)
1,300
10.4
After^Treatment
Batch volume -
30,400 liters
61
70
14,500
18,000
154,000
9.1 (supernatant,
fresh) ;
8.4 (filtered,
30 days old)
phen-2/total-23
(as CaCO3)
6,000
6,000
8,700
1,900
0.7
0.01
0.60
*tng/l unless otherwise specified.
Titanium Dioxide (Sulfate Process)
182
-------
I'e
For the sulfate process, we have examined information on all th
existing facilities in the United States. None of these plants, based
on data examined, can be considered to be exemplary. The following
description lists the raw wastes and waste segregation practices
normally used by the industry and describes planned improved treatments.
In the sulfate process, ground ilmenite ore is digested with
concentrated sulfuric acid at relatively high temperature. The acid
used is normally about 150 percent of the weight of the ore. In some
cases, small amounts of antimony trioxide are also added. The resultina
sulfates of titanium and iron are then leached from the reaction mass
with water, and any ferric salts present are then reduced to ferrous by
treatment with iron scrap to prevent coloration of the final titanium
dioxide product.
After these operations, the resulting solutions are clarified, cooled
and sent to a vacuum crystallizer. There, ferrous sulfate crystallizes
out and is then separated from the mother liquor by centrifugation.
This material is either sold or disposed of as a solid waste.
The mother liquor is then clarified by filtration after addition of
filter aid and is further concentrated by vacuum evaporation. Seed
crystals or other nucleating agents are added, and the concentrated
liquor is then treated with steam to hydrolyze the titanyl sufate
present. The resulting precipitate is collected by filtration, washed
several times and then calcined to yield titanium dioxide. The calcined
product is ground, quenched and dispersed in water. The coarse products
are separated in a thickener to which caustic soda is added to maintain
a constant pH. These coarse particles are reground and further
processed to yield a purer product.
Table 32 gives a generalized listing of the raw wastes from titanium
dioxide manufacture by the sulfate process. Data in this table are in a
form applicable to the effluent from any of the five existing sulfate
process plants. Each of these five facilities have slightly different
raw wastes due to differences in compositions of the raw ores. Table 33
lists typical ores used in U.S. manufacture of titania, with the
Adirondack and Austrailian Ilmenites being typical of ores used with the
sulfate process.
183
-------
TABLE 32. Sulfate Process Waste Streams —
Titanium Dioxide Manufacture
1. Dissolving and
Filtration
2. Cooperas (if
produced)
3. Strong Acid
. Weak Acid
5. Vent and Kiln
Scrubbing
6. TiO2 Losses
Ore and scrap iron
plus flocculants
H2SO4
Organic Carbon
FeSO4.7H2O
(as Fe)
Total Sulfate
FeSO4 (as Fe)
H2SOU
Other ore impurities
TiO2
Organic Carbon
FeSO4 (as Fe)
H2SOU (Total)
Other ore impurities
TiO2
Organic Carbon
H2SOU
Ti02
Na2SO4
0.07 x total ore and
scrap iron discharged
0.0016 x ore
0.0004 x ore plus 0.1
x C in ore
(Fe+2 + 1.50 Fe + 3) in
ore minus 0.33 x
TiO2_ in ore
1.76 x iron in copperas
0.67 x (iron in ore
minus iron in copperas)
1.07 x ore
0.67 x impurities in ore
0.03 x TiO2 in ore
0.0022 x ore plus 0.81
x C in ore
0.33 x (iron in ore
minus iron in copperas)
0.53 x ore plus 0.25
x TiO2 in ore
0.33 x impurities in ore
0.02 x TiO2 in ore
0.00025 x ore plus 0.09
x C in ore
0.01 in ore
0.016 x Ti02 in ore
0.03 x Ti02 in ore
Note: Effluents also contain traces of Pb and Cu from process
equipment. Silica and zircon do not react and are dis-
charged with the sludge.
184
-------
TABLE 33. Typical Ore Analyses* - Titanium Dioxide Manufacture
Constituent Australian Florida Australian
[Wt_.__%) Adirondack Ilmenite Ilmenite But.il§. §i§2
Ti02 44.5 55.4 64.0 96.3 71.0
FeO 38.0 23.8 3.2 10.9
Fe203 5.8 16.9 26.9 0.28
P2O5~ 0.04 0.08 0.21 0.03 0.01
V205 0.14 0.17 0,13 0.56 0.5
A1203 1.79 0.94 1.5 0.39 5.7
CaO ~ 0.58 0.02 0.13 0.01 1.0
MqO 2.14 0.27 0.35 0.05 5.0
Si02 2.48 0.15 0.3 0.28 5.0
MnO 0.50 0.72 1.35 0.01 0.3
S 0.17 0.01 0.09 0.09
CO 0.02 0.11
Cr2O3 0.01 0.14 0.10 0.20 0.2
ZrO2 0.07 0.6
Fe 0.5
C 0.27
NbO2 0.11 0.30
H 0.27 0.02
*Blank spaces indicate low impurity level or absence of. reliable
analytical data. Data from reference 14.
185
-------
Discussion of water use and treatment will be based on one facility,
chosen at random from the five plants. The specific facility used for
these modelling discussion is the plant 122 facility. A general waste
treatment flow chart for this facility is presented in Figure 57 and
generalized water usage is:
Ty.p_e £a_21/}s}S3_2f_P£2duct __ tgal/ton)
Cooling 28U (68,000) brackish 054
Cooling 83.6 (20»000) fresh 90%
Process 100 (24,000) 256
Boiler feed 16.7 (U,000) 3036
Currently, all of the process water used is fed to a settling pond to
remove suspended materials and is then discharged. The process water
discharged is from two streams, one from a solids separation part of the
process which contains strong (18-22%) acid and a second weak acid
stream coming from other parts of the process. Both streams are
currently mixed before treatment.
In the treatment of wastes, the best approach would be to segregate
these two streams and attempt to recover acid values and/or ferrous
sulfate from the more acidic stream, while applying neutralization
procedures to the other. Considering the strong acid stream first, a
possible recovery treatment is first to partially evaporate the waste to
effect further precipitation of ferrous sulfate and other metal salts
which could be recovered by filtration after cooling. The remaining
solution could be further concentrated for other use or recycled to the
process.
The weak acid stream, which does not contain sufficient metal or acid
values to justify recovery, would be oxidized to convert ferrous salts
to the ferric state and then treated with lime to precipitate heavy
metals and adjust for pH to contain about 2000 mg/1 dissolved CaCO3.
One advantage to this scheme is the possibility of further processing
the heavy metal salts recovered by acid concentration. These could
possibly be further processed to recover vanadium values, among others.
It may be noted that the above-mentioned scheme is a combination of two
treatment approaches. The method involving total neutralization and
settling is currently being installed at the plant 122 to treat all of
the waste streams. Table 3U lists some information on this treatment
process.
Effluents from four titanium dioxide sulfate process facilities are
listed in Table 35. None of these have discharge pH's in the 6.0-9.0
range for all streams, and all contain 3000 mg/1 dissolved solids. In
-------
SULFURIC ACID-i
r-TITANIUM BEARING ORE
DIGESTION
V
SETTLING
EXCESS TO
STOCKPILE
CLARIFICATION
DRYER
T
SALE
IRON REMOVAL
VWET
COPPERAS
_V
PRECIPITATION
AND SOLIDS
SEPARATION
SLUDGES
SLUDGES
STRONG ACID.
WASHING
WEAK ACID
RECOVERED
CALCINATION
Ti02 DUST
J
CALCINER
RECOVERY
SYSTEM
WET TREATMENT
SCRUB
WATER
RECOVERED
FILTRATION
AND
WASHING
Ti02
FILTRATE
00
DRYING
AND
GRINDING
RECOVERY
THICKENER
OVERFLOW/
CHLORIDE .
PROCESS—^
WASTE
STREAM
_V
SETTLING
POND
Ti02 PIGMENT PACKING
TO RIVER
FIGURE 57
SULFATE PROCESS FLOW DIAGRAM
AT PLANT 122
187
-------
some cases, strong acid streams are currently segregated and this
material, in one case, is disposed of by ocean dumping. Thus, at
present, there is no titanium dioxide sulfate process plant with an
acceptable effluent, although the 166 plant after completion of
installation of its total neutralization treatment facility may approach
the exemplary status. The neutralization procedure, along with a
possible scheme for some acid recovery, was discussed earlier in this
section. More details on possible treatment methods and their costs
will be given in Sections VII and VIII.
For the sulfate process, an alternate treatment may consist of raw ore
enrichment to remove much of the iron present before the raw material is
used in the process. One such potential process under development at
the U.S. Bureau of Mines Reno Research Center involves the smelting of
ilmenite (FeTiO^) with coal and sodium borate-titanate slag which
contains UO weight percent titanium dioxide and 0.2 weight percent iron.
Over 99 percent of the titanium in the ore is recovered in the slag,
while about 90 percent of the iron present is converted to the elemental
form. After separation of the iron from the slag, air or oxygen is
blown into the molten slag to oxidize the titanium to the tetravalent
form which is readily soluble in acid. The molten slag is water
quenched and leached in hot water to yield a sodium titanate residue (70
- 90 weight percent TiO^) in a sodium borate solution. The recovered
titanate can then be used in the sulfate process.
Sodium borate in solution is recovered by crystallization and can be
recycled to the smelting step. Use of this procedure to provide a
sodium titanate feed for the sulfate process eliminates the generation
of large amounts of iron sulfate and the inherent problems related to
its disposal.
Other methods of ore enrichment under development have been alluded to
by the various sulfate process titanium dioxide producers, but details
have not been made available.
188
-------
TABLE 34. Future Treatment at Plant 122
Methods
Neutralization of acid
to CaSOU. and oxidation
of iron, and remove
for sale or stockpile
(as ferrous sulfate)
of process wastes and
cooling water
Additional settling
ponds for cooling
waters
Estimated
Installation
Time
22 mos
22 mos
Estimated
Performance
Peduce C.O.D to Nil
Peduce acidity to Nil
Peduce Fe, Mn, V,
and Cr to Nil
TDS 50 mg/1
Reduction of suspended
solids formed due to
neutralization by 95%
189
-------
TABLE 35. Partial Discharge Data from Ti02_ Sulfate Plants(1)
Plant 142
Paramater* No_._l No,.. 2
BOD 5
COD
PH
10
71
8.0
3
145
1.2
No. 1
6
6.5
No. 2
3
5.6
Noi_3
-.
No_t_!
287
1.0
No
0
2
i_2
.3
42
.6
No. 3
0.5
27
5.0
Plant
NO. 1
5 min
Alkalinity 220
Total Dis- 1660
solved
Solids
Iron
Sulfate
Chloride
Acidity
Flow,
0.02
1,170
51.5
-
22,371
823
12,377
105
11,435
10, 200Combined
15,316
0.5
1,617
6,394
36
20,000
21
1,
7,
123,
,300
1.7
378
900
—
400
14,000
31,000
131,000
—
—
6,100-
15,400
1,000
6,800
625
20,000
20,000
3,
2,
40,
000
45
187
480
160
900
2,700
15
125
2,830
1000
30,300
5,000
100
--
--
--
cu m/day
(MGD)
(1) One
and
(2) The
(2.7)
plant of
chr ornate
_ «.
(5.5)
(32
one manufacturer is
concentrations
corporation owning this
were
.6)
not
(1.6)
(5.5)
(10
listed here. Data
.8)
(8,0)
on titanium
dioxid
provided.
facility
is currently developing
a process
for recovery and recycle of the sulfuric acid used. This process is
still under testing on the pilot plant scale.
(3) This plant barges its strong acid wastes out to sea for disposal. This
method of disposal of highly acid wastes containing large amounts of
dissolved heavy metals is not considered satisfactory. Effluent No. 3
is the available data on material dumped at sea.
*mg/l unless otherwise specified
190
-------
Substitution of sodium titanate for ilmenite as a sulfate process raw
material would lead to a sulfate - bisulfate by-product which could be
recovered by crystallization (as is done with ferrous sulfate) for sale.
This would eliminate much of the heavy metal salt discharge problems
with the sulfate process and also solve the problem of acidic discharges
via recovery of a low grade sodium bisulfate by-product for sale or
other use.
This approach may prove to be a superior approach to either the
neutralization scheme or the acid recovery techniques mentioned earlier.
The economics of the above mentioned possible sulfate process
modification have not yet been reported. A more detailed evaluation of
this possible process must await such an economic presentation.
Titanium Dioxide (Chloride Process)
Virtually the same process is used at the two chloride process
facilities studied (plants 009 and 160). The only process differences
lie in the types of ore used. See the earlier Table 33 for typical ore
compositions. Plant 160 employs a unique process using an ore
containing 66 percent titanium dioxide, while plant 009 uses only 95
percent plus grades of rutile and upgraded ilmenite, and nence has a
more exemplary effluent. Figure 58 and 59 show the process flows within
the 009 facility.
The raw wastes from plant 009 consist of heavy metal salts, waste coke
and hydrochloric acid. In the raw waste stream, these are actually
metal chlorides before waste treatment. In detail, the raw wastes are:
Iron salts (equiv. Fe203l) 58 (116)
Other metal salts 58 (116)
(equiv. metal oxides)
Ore 138 (276)
Coke 23 (46)
Titanium hydroxide 29 (58)
TiO2 40.5 (81)
HC1 227 (454)
Plant Water Use
Input:
cu m/day JMGD) 1/kkg (gal/ton)
Lake 11,500 (0.304) 17,100 (4,100)
Municipal 76 (0.020) 1,130 (270)
191
-------
to
0n ..... . --.
WASTE SLUDGES
TiCI4 '
TiCl4 , FeClx
COKE, ORE, COjj.Njj.CO^ w w
I
COKE } CHLORINATOR ^ ^ QUENCH ^. TiC'4
COKE > LMLUNINATUK 2 TOWER ^CONDENSATION
ORF —- m "^
TIT)
\'
WATER >
V
WASTE
SLURRY
• 1 EVERYTHING EXCEPT
gQLIQ RECOVERED ORE^
WAS TtS
FeCI,, ORE, L.. .:s I.
1 COKE ORE J_
V LIQUID "1 , RECOVERY
WASTES '
HOI ...
L FeC|x j
ORE
'URIFICATION COOUNG
CHEMICALS WATER
V \I/
TiCI4 TICI4
^ PURIFICATION ^ STORAGE
COOLING WATER V V
Ti02 TiCI4
PLANT SALES
v
v, WASTE
~^ TREATMENT
FIGURE 58
^NIUM TETRACHLORIDE PORTION OF TITANIUM DIOXIDE PLANT
-------
TICI4 VAPOR-
LIQUID
TiCl4
VAPORIZER
PURCHASED BY PIPELINE -
COOLING WATER
CO
GENERATOR
^
->
OXIDATION
REACTOR
COOLER
-SPENT COOLING WATER•
WASTE TREATMENT
AT Ti02 OPERATION
CI2,02,C02,N
COLLECTION
COOLING FUTURE _^FUTURE WASTE TO Tjcu
WATER SCRUBBER ^PORTION ^
X t
C\2
RECOVERY
SYSTEM
WATER
Ti02
SLURRY
SYSTEM
1
WASTE
WASTE TREATMENT
AT TiCI4 OPERATION
<-
—LIQUID CI2—>TiCI4 PROCESS
WASTE
h-COOLING WATER—> J^TIO^^
OPERATION
VARIOUS
TREATMENT
CHEMICALS
1
Ti02
TREATMENT
WASTE
Ti02, SPILLS, SALTS
-STORM DRAINAGE FROM Ti02 OPERATION
WASTE TREATMENT AT TiOg OPERATION
FIGURE 59
TITANIUM DIOXIDE PORTION OF PLANT (CHLORIDE PROCESS)
-------
% Recycled
Use:
Cooling 58,700 (15.5) 876,000 (210,000) 93
Process 6,060 (1.6) 90,500 (21,700) 0
Cleanup 28U (0.075) 4,220 (1,010) 0
Sanitary 38 (0.01) 560 (140) 0
Boiler feed 834 (0.22) 12,500 (3,000) 0
Treatment
Most of the cooling water is recycled. The waste treatment methods used
on the effluent stream, which consist of neutralization, precipitation
and settling of heavy metal salts prior to discharge, are shown below.
Figures 60 and 61 show the treatment processing at plant 009.
Tr eatment
Stream No. Source Methods Disposal
1 TiClU precipitation Neutralization, Lake
settling
2 Cooling Neutralization, Lake
settling
Table 36 shows the plant 009 effluents after neutralization and settling
treatment. The effluent consists of a neutral pH stream containing
dissolved salts (mostly sodium chloride) and low heavy metals
concentrations. Table 37 shows verification measurements at this
facility.
194
-------
STORM DRAINAGE
1
RETENTION
BASIN
TiCl4
WASTE -
STREAM
PROCESS
WASTE
STREAM
CaO
I
SUMP PUMP
3 STAGE
NEUTRALIZATION
SYSTEM
FLOCCULENTS-
SUMP PUMP
CLARIFIER
ALSO SURGE FOR
STORM WATER
RUN-OFF
UNDERFLOW
THICKENER
L
POLISHING
POND
TiCI4
->PORTION
OUTFALL
POLISHING
POND
UNDERFLOW
ROTARY
FILTERS
_V
FILTER CAKE TO
'LAND STORAGE
FIGURE 60
TREATMENT, TITANIUM TETRACHLORIDE
OF PLANT 009
195
-------
STREAM-
o
{E«
C i«>
fe8
If
IK
O.O
i
MOSTLY COOLING WATER
^
STORM
DRAINAGE
SYSTEM
V
RETENTION
BASIN
SUMP
PUMP
-^
\/
SUMP
PUMP
1
SETTLING
\
-------
TABLE 36. Composition of Plant 009 Effluent Streams
After Treatment
Parameter* . Average
Suspended Solids 18
Total Dissolved Solids 3300
COD 50
pH 7.8
Temperature, °C 16
Organics
Turbidity (Jackson Units) 20
Color (APHA Units) 10
Chloride 1650
Sulfate
Sulfat.e
Iron
Copper
Chromate
Total Chromium
Arsenic
Mercury
Lead
0.2
0.015
0.01
0.05
0.02
0.001
0.14
i_Noi_l
Range
1-50
1500-4500
40-90
6.0-9.0
7-27
Stream
Average
15
300
20
6.8
16
NOj_2
Range
0-40
180-900
5-45
6.0-9.0
2-32
(Ambient Temp.)
None were
10-80
10-20
750-2050
1-2.5
—
0-3.0
0.01-0.03
0.01-0.15
0.1-0.19
found
20
10
50
—
150
0.2
0.015
0.01
0.05 0.
0.02
0.001
0.02
10-50
10-20
70-100
1-2.5
90-450
0.1-1.0
0.01-0.03
01-0.15
0.02
*mg/l unless otherwise specified
197
-------
TABLE 37. Verification Data of Plant 009
Parameter*
Flow, cu m/day (MGD)
Temperature, °C
Color (APHA Units)
Turbidity (FTU)
Conduct ivity
Suspended Solids
PH
Acidity: Total
Free
Alkalinity (Total) P
T
Hardness: Total
Calcium
Halogens: Chlorine
Chloride '
Fluoride
Sulfate
Phosphates (Total)
Nitrogen (Total)
Heavy Metals:
Iron
Chromate
Oxygen (Dissolved)
Lake
Intake Water
3650 (0.964)
9
100
35
100 (Nad)
25.0
7.9
N/A
N/A
0 (CaCO3)
93 ,(CaC03)
129 (CaC03)
97 (CaCO3)
0
36.5
0
32.0
1.4
0.24
0.225
0 (Cr+6)
10.8
Effluent
Stream tl
6060 (1.60)
16
1UO
35
2100 (NaCl)
10
7.6
N/A
N/A
0 (CaCO3)
22 (CaC03)
2600 (CaC03)
1920 (CaCO3)
0
2250
0.3
240
0.025
0.14
1.6
0 (Cr+6)
9.0
Effluent
Stream t2
2240 (0.590)
26.5
90
30
170 (NaCl)
30
6.85
0 (CaC03)
0 (CaC03)
0 (CaC03)
28 (CaC03)
185 (CaC03)
139 (CaC03)
0
49.5
0.25
175
0.225
1.3
0.4
0
.6.2
(Cr+6)
*mg/l unless otherwise specified
19S
-------
VERIFICATION SAMPLING AND ANALYTICAL METHODS
Sampling Operations
Two teams of two men each were assigned to the field sampling and
measurements operations. Each of the teams was equipped with a station
wagon and a 4.7-meter trailer outfitted as a mobile water testing
laboratory. The visit of a team to each facility was preceded by a
visit to the plant by one of the senior engineers on the project team.
During this visit, effluent streams and potential sampling sites were
determined and approximate expected stream compositions were
established.
The duties of the field team visiting the plant included measurement of
flow rate and collection of samples at each designated sampling site.
Methods used to determine flow rates varied from stream to stream, bur.
included: (1) Use of existing weirs or installed flow meters; (2) Use of
current meter plus dimensional measurements; (3) Direct collection of
small outfall streams, with volumetric measurement related to duration
of collection; (4) Use of dye tracer to give velocity measurement (plus
dimensional measurements).
Since many of the streams of interest could not be approached, the
wastes contained therein were sampled after having mixed with one or
more other streams.
For most effluent sampling sites, four one-liter samples were taken (one
per hour) over a four-hour duration. These samples were then mixed to
give a four-liter composite sample. One four-liter grab sample was
taken of the water supply to the plant. At the end of the day, a four-
liter grab sample was taken at each sampling site (and of the water
supply) for backup.
One-half of the four-liter composite sample was used for analyses and
tests in the field laboratory. The remaining two liters of composite
sample were divided into several samples, some of which were acid-
stabilized, and were transported to our Springfield, Virginia facilities
for further analyses. Basis of Analytical Method Selection
It was the philosophy of this program to adopt and to utilize practical
analytical methods which were reliable and easily used in the field.
This decision was dictated by several considerations involving the
necessity to accomplish sampling and analysis in a large number of
selected plants, plus the doubtful nature of the conventional
stabilization methods (such as addition of nitric acid to metal
solutions; sulfuric acid to COD samples; and mercuric chloride to
nitrogen samples) when applied to the often complex discharge streams
encountered in this study. Backup analyses were performed in the
analytical laboratory at the home office for those not practicable in
199
-------
the field and to provide analyses conforming to the accepted standard
techniques. (12)
The results obtained by the use of the field transportable test methods
were, in general, quite reliable. As a routine matter, however,
standard test samples were inserted into the analytical program to allow
some estimate of the validity of the results reported front the field.
The unlabeled standard samples were made up from EPA Reference Samples
and presented to the analytical personnel without obvious
identification.
The analysis of the samples from various process and discharge streams
has been a somewhat complex procedure. This is due primarily to the
extraordinary variation in flow rates, concentration of solutes and (in
particular) the extremely wide range of suspended solids which was
encountered.
However, analytical techniques were utilized which were judged to yield
the maximum results within the time limitations of the study.
Pretreatments in the field for the various types of samples were:
(1) Suspended and dissolved solids - none;
(2) Metal ion analysis - addition of 5 ml of concentrated nitric acid
per liter of sample;
(3) COD analysis - used immediately in the dichromate reflux apparatus
or treated with 1.0 N sulfuric acid;
(4) Nitrogen analysis - used immediately or treated with mercuric
chloride for stabilization;
(5) Phosphorus - addition of 40 mg. of mercuric chloride per liter; and
(6) Fluoride - none.
The analytical methods used in the field are described briefly below:
Dissolved Oxygen, Temperature and pH
Dissolved oxygen and temperatures were measured in situ using remote
probes. The pH was measured immediately after sampling with a Chemtrix
type 40/40E pH meter (standardized to pH 7 before each measurement).
Color
Apparent color was determined by direct comparison of the sample with
platinum-cobalt standards. One unit of color is that produced by 1 mg/1
of platinum in the form of the chloroplatinate ion. To preclude changes
during storage (biological activity, for example), measurements were
made in the field as soon as possible after sampling.
Turbidity
200
-------
The method was based on a comparison of the intensity of light scattered
by the sample under well-defined conditions with the intensity of light
scattered by a standard (formazin) suspension under identical
conditions. Analysis was accomplished in the field as soon after
sampling as possible using a turbidimeter calibrated with formazin
polymer suspension.
Conductivity
The specific conductance of the sample was obtained by direct
measurement using a conductivity meter. Sample preparation required
protection from atmospheric gases and the adjustment of pH using gallic
acid (0.2 gm/50 ml sample). Results were reported in mg NaCl/1
equivalent at 25°C.
Acidity
Acidity was determined by titration with Standard N/44 sodium hydroxide
to the carbonic acid equivalence point (pH 4 to 5) using methyl orange
as a colorimetric indicator to determine "free" acidity, and then
further to the bicarbonate equivalence point (pH 8.3 using
phenolphthalein) for "total" acidity. These measurements were made in
the field as soon as was practical after sampling.
Alkalinity (Phenolphthalein and total)
Phenolphthalein alkalinity was determined in the field as soon as
possible by titration of the unaltered sample with Standard N/50
sulfuric acid to a phenolphthalein endpoint.
Total alkalinity was determined by addition of a bromcresol green-methyl
red indicator solution at the phenolphthalein endpoint and titrating
with standard N/50 sulfuric acid until the color changed from green or
blue-green to pink.
Hardness (Ca & Total)
Hardness was determined in the field using EDTA titration with Chrome
Black T as an indicator.
Chloride
Total chlorine was determined in the field as soon as possible after
sampling by the orthotolodine method wherein the color intensity is
determined at U90 nanometers (nm) .
Chloride
Chloride (expressed as mg/1 chloride) was titrimetrically determined in
the field using mercury nitrate with mixed diphenylcarbazone-bromphenol
201
-------
blue indicator. The endpoint of the titration was the formation of the
blue-violet mercury diphenylcarbazone complex.
Sulfate
Sulfate determinations were made in the field using the barium sulfate
turbidimetric method with a spectrophotometer. A calibration curve for
the spectrophotometer was prepared from standard sulfate solutions.
Nitrogen
Nitrogen/nitrate determinations were made in the field using the cadmium
reduction method with 1-naphthylamine sulfanilic acid as the indicator.
The resulting color was determined spectrophotometrically at 525 nm.
Hydrogen Sulfide
Hydrogen sulfide content was determined by stripping sulfide from an
acidified sample by lead acetate paper. Color comparison then allowed
estimation of mg/1 of hydrogen sulfide.
Chemical Oxygen Demand
COD was determined in the field as soon as possible after sampling using
the dichromate reflux method with readout accomplished
spectrophotometrically at 600 nm.
Fluoride
Analyses for fluoride, total dissolved solids, total suspended solids,
and elemental phosphorus were performed in the fluoride ion
determinations were carried out with an Orion specific ion electrode
(Model 94-09; a silver - silver chloride - lanthanum fluoride crystal
cell) used with an Orion Model 801 meter. All samples and standards
(made up with reagent grade sodium fluoride) were diluted with a total
ionic strength adjustment buffer to bring the sample pH to between 5 and
6, to eliminate complexing with the polyvalent ions Si+4, Al+3, and Fe+3
and finally to bring the total ionic strength for sample and standards
to a constant level. A calibration curve of electrode potential in
voltage versus fluoride concentration was constructed, from which the
concentration of fluoride ion in the unknown was determined. This
method is also known as Storet 00950.
Total Dissolved Solids
A standard glass fiberA well-mixed sample is filtered through a standard
glass fiber filter, a Reeve Angel type 984 H. The filtrate is
evaporated on a steam bath and dried to constant weight at 180°C. These
202
-------
analyses were carried out using the procedures outlined as Storet No.
70300 and Storet No. 00530 in "Methods of Chemical Analysis of Water and
Wastes" (1971) . To determine the precision of these methods, a standard
solution of sodium chloride was analyzed which contained 247 mg/1
(dissolved solids standard). The method showed a consistent error of
less than 0.1%. On the other hand, an attempt to use a suspension of
Ti(D2 in water as a reference standard for suspended solids has proved to
be quite undependable; this observation is clearly in line with the
comment "the precision and accuracy data are not available at this time"
(for Storet OOSOO) , from "Methods of Chemical Analysis of Water anrl
Wastes", op. cit.
Elemental Phosphorus
The method for phosphorus consisted of oxidation to orthophosphate by
nitric acid, followed by ascorbic acid addition and colorim-tric
determination of orthophosphate.
Presentation of Available Day-to-Day Plant Effluent Data Heavy Metals
Metal concentrations were determined, as required, by Penniman and Brown
(Registered Analytical Chemists) Baltimore, Maryland, using conventional
atomic absorption methods.
EFFLUENT DATA ANALYSIS
Presentation of Available Day-to-Day Plant Effluent Data
It was found not to be possible to collect day-by-day effluent data from
the many plants sampled in this study in order to do an extensive
statistical treatment of data. Such data was obtained from a very few
plants and the following comments were constructed from them to set the
groundwork for the analysis of data as was carried out on all the
various plants for which no statistical bases were available.
To convey the clearest possible picture of the effluent data acquired
from several plants, the presented data-samples (Figures 62 through 73)
have been arranged in a dual format, as follows: (a) Range of effluent
variation over the time-domain of the sample; and (b) Percentage
frequency of readings over the range of the effluent-variation.
Inspection of the time-domain plots (which were automatically plotted by
day from industry-supplied tables of raw data) indicates the existence
of higher frequencies of variation by the "spiky" appearance of the
graph.
Of more significance is the magnitude of such variations. Observe that,
in Figure 62, the amplitude varies over an order of magnitude. In
particular, the minimum value recorded was 727.3, while the maximum was
203
-------
7590.9. For this run, the standard deviation, was calculated as 1441.9,
and if we defined a normal 95% confidence- interval for the mean, /( =
3567.7, by
(where n = 182 is the number of data-points in the sample) , this would
imply that the mean is 95% certain to lie between 3363 and 3790.
However, more than 65% of the readings fall below the lower limit of
this confidence interval, as can be seen by an inspection of Figure 63.
Thus, it is obvious that neither the mean nor the calculated confidence
interval is completely meaningful.
The fact of the matter is that the variations in the effluent are
neither random, stationary, nor closely controlled. For example, the
week-long minimum early in 5-73 (due to a strike, in this case) weights
the data on the low side. But, over a sufficiently long sample, such
occasions could arise several times and, if unaccounted for, could bias
the results heavily.
A better approach seems to be to regard the percentage-frequency
histogram as something akin to a "distribution pattern". If, an
increase in control measures could substantially reduce the frequency of
readings above that level. Put another way, if a process can be
sufficiently well-controlled to limit a large majority of its effluent
readings to a relatively low (or even marginally acceptable) level,
there seems little reason not to demand that all such readings remain
below that level, except, perhaps, for particular singular events which
may be beyond control.
Consider Figures 68 and 69 and Figures 70 and 71 as examples. In Figure
68, variations in concentration range over two orders of magnitude,
while in Figure 70, the variation in total mass the standard-deviations
exceed the mean-values. However, inspection of Figures 69 and 70
indicates that, in both cases, better than 65% of the readings lie below
the mean value. Manifestly, a process which could be described as
we 11- con trolled is not being considered. Indeed, if 65% of the daily
readings over six months lie below the mean-value of the six month
sample, any limitation based upon a normal standard deviation is little
limitation at all. In fact, should the normal 95% again be utilized
confidence interval for the mean, as previously, in the case of Figures
68 and 69 that the mean (637.9) is 95% certain to lie between
(approximately) 539 and 737; whereas, for the case of Figures 70 and 71,
the mean (3290.4) is 95% certain to lie between (approximately) 2770 and
3810. Inspection of the percentage frequency histograms indicates that
over 50% of the readings (in both cases) lie below the lower level of
the 95% confidence interval. As might be expected, comparison of Figure
68 with 70 serves to illustrate the accentuation of the variations in
concentrations by the variations in flow-rate.
204
-------
4
mean:
3567.7"
Plant 030
12/72 1/73 2/73 3/73 4/73 5/73
FIGURE 62. Time Variation of Effluent Chloride Ion Concentration at Plant 030
201
lOt
01
Plant 030
Cl-1on..,
12/72-5/73
1
mean: 3567.7 kg/day
0 3 6 g 12 15 18 21 24 27 30 33 36 39 42 45 46 51 54 57 60 63 66 69 72
10' kg/day
FIGURE 63. Frequency Distribution of Effluent Chloride
Ion Concentration at Plant 030
205
-------
25J
20t
IS!
101
SI
01
8/72 9/72 10/72 11/72 12/72 1/73
FIGURE 64. Time Variation of Effluent Mercury Concentration at Plant 144
Plant 144
Hg
8/72-1/73
mean: 3.27-10"'
Hg (10"' ppn)
10 ' 11 12 13 14 15
FIGURE 65. Frequency Distribution of Effluent Mercury
Concentration at Plant 144
206
-------
1.78.10""
8/72
9/72
10/72
11/72
12/72
20t
FIGURE 66. Time Variation of Effluent Mercury Daily
Discharge at Plant 144
Plant 144.
Hg
8/72-1/73
10*
J
mean: 1.78-10"
\
IS
20
30
40 45 50
Hg (10"' kg/day)
FIGURE 67. Frequency Distribution of Effluent Mercury
Dally Discharge at Plant 144
-------
0 I—
Mint 144
Cl-lon
e/H-i/rt
8/72
9/72
\m
FIGURE 68. time Variation of Effluent Chloride
ion Concentration at Plant 144
101
-------
8/72
9/72
10/72
11/72
12/72
1/73
FIGURE 70. lime Variation of Effluent Chloride Ion
ua
-------
(discontinuities Indicate absence of collected
-------
A prime example of the deceptive nature of average-values is clearly
exhibited by Figure 72 and 73. Here, a six-month average of pH readings
provides us with a mean of 6.99 (highly favorable) and a standard
deviation of 1.44. Again taking the normal 95% confidence interval for
the mean, we find that the mean is 95% certain to lie between 6.8 and
7.2. However, inspection of Figure 72 shows that (midway through 8-72)
in four successive days, the pH of the effluent ranged from 3.9 to 11.0
to 2.7 to 10.8. This type of variation would obviously conflict with
any reasonable guideline which could be set. Although there can be some
reservations taken about the mathematical averaging of pH values, which
are really the negative logarithms of the hydrogen ion concentrations,
this operation was carried out to be illustrative. If the pH data cited
above is reinterpreted as hydrogen ion concentration, the mean value
corresponds to a pH of 4.4, which we believe to be highly misleading of
the performance of this plant.
Thus, final analysis of the raw data of a dangerous pollutant (mercury),
as illustrated by Figures 64 through 67, shows that conclusions must be
carefully considered. Concentration is found to have a mean of
approximately 3.3.10-mg/l, with a standard deviation of about 2.03.10-.
Daily amount data indicates a mean of 1.78.10- kg/day with a standard
deviation of 1.06.10-. It is observed throughout, variations are being
dealt with which have standard deviations on the order of their mean-
values. Put the percentage-frequency histograms yield a better
indication of what is actually going on. Figure 65, for example, shows
that concentration is relatively well-controlled. The spread of the
readings about the mean is reasonably limited, and one could reasonably
conclude that some care has been exercised with the process. Proceeding
to Figure 67, however, it is clear that a much wider scatter of data
points is present in the mass per day sample. Clearly, such scatter
arises from variations in flow rate, which indicates that concentration
data, alone, are insufficient to provide an adequate assessment of a
potential effluent problem.
On the basis of the available data, it is hardly possible to arrive at a
satisfactory statistical justification for any "hard" limitation placed
on effluent outputs. On the other hand, if we can assume that these
data samples are not unrealistic over the industry as a whole,
inspection of the relevant percentage-frequency histograms clearly
indicates that "most" of the time the effluent outputs are kept at
generally lower levels than the sample-means, by themselves, would
indicate. consequently, it is not unrealistic to assume that the actual
"most probable population-value" would lie considerably lower than the
calculated means. Assuming this to be the case, it follows that
calculated means would tend to be "high" (at least over runs on the
order of six months or more) -- and, therefore, limitations based upon
such means should certainly not be excessively restrictive.
Limitations of Statistical Treatment of Data
211
-------
The intent of this program has been the construction of effluent
limitation guidelines for the inorganic chemicals industry. For such
guidelines to be defensible, they must be both realistic and realizable.
To be administratively useful and enforceable, they must afford a
standard basis of comparison between similar operational processes and
lend themselves to practical and economical monitoring operations.
Limitations, however, imply a bound to variation; consequently, it is
the degree to which such bounds satisfy the above criteria that
determines the effectiveness of the limitation. But, realistic bounds
can be constructed only when sufficient knowledge of the extent and the
apparent nature of existing effluent variations is accumulated. For
this reason, significant effort has been expended throughout the program
in attempts to acquire (whenever it existed) records of monitoring data
sufficiently complete to aid in the characterization of these effluent
variations as they actually occur in practice. While this endeavor has
not met with the success desired, it seems clear from the samples
obtained that, if they are representative of the industry as a whole, a
high degree of caution should be exercised in their analysis.
The ultimate value of conclusions based upon numerical results is
necessarily determined by the reliability of the data and the validity
of the methods by which these data are analyzed. Failure to realize the
importance of a continued appraisal of such factors can lead to
misdirected effort and expense, and, in extreme cases, may result in
unrealistic decisions.
A random (stochastic) process is distinguished by the fundamental
indeterminacy of its behavior. Over a run of measurements, a random
process exhibits variations from observation to observation which no
amount of effort or control exercised in the course of the run can
remove. Furthermore, knowledge of the past behavior of the system over
any particualr run cannot be expected to yield any precise indication of
its future action. Any single output from a random process is
essentially an accident which is unlikely to occur again. With such
processes, the standard procedure is to replicate (to the limit of
practicality) whatever runs of measurements are of interest, and to
utilize the ensemble of collected records to characterize the nature of
the statistical variations involved. Once this has been accomplished,
reasonable statements concerning the probable spread of future process-
values (all salient process parameters remaining fixed) can be made.
Such well-defined systems are essentially non-existent in the chemical
process industries. That such a situation prevails can be appreciated
by noting that only in the most rigidly controlled processes should we
expect anything approaching random variations. As control diminishes,
nonrandom effects, nonstationary variations, and singularities begin to
appear in the output data. However, the population mean is the "best,"
or most probable output value only if the system variations observed are
the result of small, random, independent, and additive effects. Once
212
-------
nonrandom or nonstationary variations are present, the mean may differ
significantly from the most probable value of the population.
Similarly, the standard deviation becomes useful in establishing
confidence-intervals only when the standard error of a known statistic
is known or can be estimated. Without such knowledge, the data must be
treated most carefully, and specific conclusions must be cautiously
constructed.
213
-------
SECTION VI
SELECTION OF POLLUTANT PARAMETERS
PRIMARY WASTE WATER POLLUTION PARAMETERS OF SIGNIFICANCE
The primary or Group I parameters are those deemed significant for the
inorganic chemicals, alkali and chlorine industry in terms of effluent
volume or degrading impact on receiving water quality. The Group I
parameters of pollutional significance for the industry include:
PH
Total Suspended Solids (TSS)
Chromates
Harmful Metals:
Arsenic
Cadmium
Chromium
Iron
Lead
Mercury
SECONDARY WASTE WATER POLLUTION PARAMETERS OF SIGNIFICANCE
The Group II parameters are those considered important due to their
impact on water quality, but which, except TDS, occur only in limited
quantities or only from a particular process. These parameters include:
alkali and alkaline earth metals, ammonia,chloride, chlorine, chlorinated
hydrocarbons, cyanides, fluoride, nitrate, nitrite, phosphates, phenols, and
cyclic hydrocarbons, Chemical Oxygen Demand (COD), silicates, sulfate,
ulfite, emperature, Total Dissolved Solids (TDS), Other Harmful Metals:
aluminum, copper, nickel,manganese, ra'olybdenum, tin, titanium, vanadium, z inc.
SIGNIFICANCE OF POLLUTION PARAMETERS
In the inorganic chemical industry, the most significant pollution
parameters were determined to be total suspended solids (TSS) and the
presence or absence of harmful quantities of metals or other materials.
These parameters are important for every chemical studied. Other
specific parameters, such as chloride, sulfate, phosphate, COD, etc.
should be considered for individual chemical plants on a case-by-case
basis.
Group I parameters are those which will have a large impact on receiving
water quality and should be monitored routinely and with some degree of
frequency.
215
-------
Group II parameters, except TDS, are those occurring in waste waters
from a particular process or manufacturing operation. They need to be
routinely monitored less frequently except for those processes where
they are generated.
RATIONALE FOR SELECTION OF POLLUTION PARAMETERS
The justification for the selection of the Group I and Group II
parameters for the inorganic chemicals, alkali and chlorine industry is
given below.
Chemical Oxygen Demand (COD)
Certain waste water components are subject to aerobic biochemical
degradation in the receiving stream. The chemical oxygen demand is a
gross measurement of organic and inorganic material as well as other
oxygen-demanding material which could be detrimental to the oxygen
content of the receiving water. It is a Group I parameter.
Cyanides
These materials are of concern because of their toxicity, although they
are biodegradable in the receiving stream. The approved analytical
methods do not differentiate between complex cyanides and simple
cyanides, which may have different toxicities. They are a Group II
characteristic because they were encountered in the waste water effluent
from one process in this study, that of the electrolytic method for the
production of hydrogen peroxide.
Ammonia
Ammonia is of concern, because it exerts an oxygen demand on the
receiving stream, as well as being toxic to fish and aquatic organisms.
It is a Group II parameter as it is encountered in soda ash, calcium
chloride, and nitric acid manufacture.
Nitrate
Nitrates are of importance in water supplies used for human or livestock
consumption because high nitrate concentrations can become toxic. From
investigations of this toxicity, it has been concluded that the nitrate
content in terms of nitrogen should not exceed 20 mg/1 in public water
supplies(15). The U.S. Public Health Service(16)recommends that nitrate
concentrations in ground water supplies not exceed 10 mg/1 nitrate as
nitrogen. It is a Group II parameter as it is encountered primarily in
nitric acid manufacture or use.
216
-------
Nitrite
This parameter is reported as nitrite nitrogen. It occurs between
ammonia and nitrate with respect to the oxidation status of nitrogen.
In cases where the conditions exist, for oxidation to nitrate it would
impose an oxygen demand on the receiving stream. It is considered a
Group II parameter found mainly in boiler treating chemicals.
Total Dissolved Solids (TDS)
The total dissolved solids is a gross measure of the amounts of soluble
pollutants in the waste water. It is an important parameter in drinking
water supplies and water used for irrigation. A total dissolved solids
content of less than 500 mg/1 is considered desirable. It is a Group II
characteristic found across the board in this industry. From the
standpoint of quantity discharged, TDS could have been considered a
Group I characteristic. However, energy requirements, especially for
evaporation, and solid waste disposal costs are so high as to preclude
limiting dissolved solids at this time.
Total Suspended Solids (TSS)
The measure of suspended solids as a parameter serves as an impor^srit
indicator of the efficiency of solid separation devices such as
clarifiers and settling ponds. The total suspended solids are a source
of sludge beds in receiving streams. This is a Group I parameter found
across the board in the industry.
Fluoride
This parameter is of concern because of its toxicity to aquatic
organisms at certain concentrations and drinking water standards which
limit its conrent. It is a Group II parameter found mainly in the
manufacture of hydrofluoric acid and its use.
Chloride
Chloride is important in water supplies used for drinking purposes or
for irrigation. A total chloride content of less than 500 mg/1 is
considered desirable by the U.S. Public Health Service for drinking
water purposes. It is a Group II parameter found across the board in
this industry.
Sulfate
Sulfate may be a large fraction of the TDS. It is a Group II
characteristic in this industry, found as a spent warer treatment
chemical, in the manufacture of sulfuric acid and operations using
sulfuric acid as well as titanium dioxide sulfate process and
manufacture of sulfate compounds.
217
-------
Sulfite
Sulfite is an intermediate oxidative state of sulfur, between sulfides
and sulfates. It exerts a chemical oxygen demand on the receiving
stream. It is a Group II parameter found in sodium sulfite manufacture
and in one of the sulfur dioxide removal treatments.
Acidity/Alkalinity
Acidity and/or alkalinity, reported as calcium carbonate, are
quantitative measurements of the amount of neutralization to be required
in the receiving stream. There does not appear to be any need for their
determination in effluent waste waters when the pH is between 6.0 and
9.0
PH
pH is a measure of the acidity or alkalinity of a solution, with a pH of
7.0 defined as being neutral. The range of pH of the effluents from
this industry is generally between 6.0 to 9.0. This is a Group I
parameter across the board in this industry.
Phosphates
Phosphates, reported as total phosphorus(P) , contributes to
eutrophication in receiving bodies of water. It is a Group II
characteristic for this industry found primarily in water treatment
chemicals.
Chromates
Chromates are reported as hexavalent chromium, which is a known harmful
material. It is a Group I parameter found primarily in water treatment
and conditioning, and as such is found across the board in the industry.
Harmful Metals
The following metals are frequently encountered in water pollution
control problems, particularly when they are used in water conditioning
applications. Although they are generally encountered in relatively
small amounts, they are all harmful to some degree:
Arsenic Iron
Cadmium Lead
Chromium Mercury
They are all considered Group I parameters where they are used as in
water treatment or produced by the manufacturing process.
218
-------
Other Harmful Metals
This class of metals is much less frequently encountered being primarily
derived as by-products of mineral raw materials or normal corrosion of
process equipment. They include:
Aluminum Tin
Copper Titanium
Manganese Vanadium
Molybdenum Zinc
Nickel
They are considered to be Group II parameters.
Alkali and Alkaline Earth Metals
These metals, sodium, potassium, magnesium, calcium, and barium, are
Group II parameters for this industry. When TDS is exceptionally high
or the receiving stream is used for irrigation water supply, these
metals merit attention as pollutants. Barium salts are of very low
solubility, but harmful.
Chlorine
Chlorine is of concern because of its known toxicity to fish, bacterial
organisms and aquatic organisms. It is a Group II parameter encountered
in chlor-alkali, aluminum chloride, and hydrochloric acid manufacture.
Chlorinated Hydrocarbons
These materials are of concern because of toxicity under certain
conditions to fish and aquatic organisms as well as taste and odor
problems in water supplies. They are a Group II parameter being found
primarily in chlorine processes.
Phenols, and Cyclic Hydrocarbons
Although phenols are biodegradable, they sometimes persist in the
receiving stream and produce taste and odor problems in water supplies
and taint fish .flesh. Phenols are a Group II characteristic found
primarily in operations producing coke as a raw material. Cyclic
hydrocarbons are found in hydrogen peroxide manufacture.
Silicates
Silicates contribute to eutrophication in receiving bodies of water. It
is a Group II parameter for the industry found primarily in silicate
manufacture or by-product of mineral raw materials.
219
-------
Temperature
Temperature is a sensitive indicator of unusual thermal loads where
waste heat is involved in the process. Excess thermal load, even in
non-contact cooling water in the inorganic chemical industry has not
been and is not expected to be a significant problem* It is a Group II
parameter.
220
-------
SECTION VII
CONTROL AND TREATMENT TECHNOLOGY
The best practicable control technology currently available (BPCTCA) and
best available technology economically achievable (BATEA) for the
several segments of the inorganic chemicals, alkali and chlorine
industries of this study are summarized in Table 38. Each chemical is
discussed in detail on the following pages.
SPECIFIC CONTROL AND TREATMENT PRACTICES IN THE INDUSTRY
Aluminum Chloride
Direct chlorination of aluminum to produce aluminum chloride is a
relatively simple process. Plants are small (9 to 18 metric tons/day).
Since the process is so simple, plant age is not an important factor.
There is no process water involved, nor usually any cooling water. The
only source of water wastes is from equipment used to treat air-borne
wastes such as aluminum chloride dust around the packing station and
aluminum chloride and chlorine from the air-cooled condensers.
In some plants, run on the aluminum-rich side (white or gray aluminum
chloride), there is very little chlorine in the discharge from the air-
cooled condenser. Also, the gas volume from the condenser is sucn that
only a very small quantity of aluminum chloride is discharged. In such
plants there may be no air pollution control provision. One of the
exemplary plants of this study operates in this fashion. In plants
operating on the chlorine-rich side (yellow aluminum chloride), water
scrubbing of the air condenser discharge gases is needed. Provisions
for this treatment vary from none to exemplary, depending on the plant
involved.
At least three practicable, economically feasible, and low energy air
pollution control approaches are available:
(1) No air or gas treatment for gray or white aluminum chloride.
(2) Gas scrubbing and sale of scrubber wastes. This approach is taken
by an exemplary plant of this study.
(3) Gas scrubbing followed by chemical treatment to precipitate aluminum
hydroxide and convert chlor'ine to sodium chloride. Technology available
from the chlor-alkali and titanium dioxide chloride process may be
applied. Costs for this treatment process are developed in Section VIII
to demonstrate its economic reasonableness.
221
-------
TABLE 38. Summary of BPCTCA and BATEA
Chemical
BPCTCA Best Practicable Control
Technology Currently Available
Guideline BPCTCA
BATEA
Guideline
Best Available Technology
Economically
Achievable
BATEA
Category 1
Aluminum
Chloride
(Anhydrous)
Aluminum
Sulfate
Calcium
Carbide
Hydrochloric
Acid
Chlorine
Burning
Hydrofluoric
Acid
Sodium
Bicarbonate
Sodium
Chloride
(Solar
Process)
Sodium
Silicate
No discharge of
pollutants in
process waste
waters
No discharge of
pollutants in
process waste
waters
No discharge of
pollutants in
process waste
waters
No discharge of
pollutants in
process waste
water
No discharge of
pollutants in
process waste
waters
No discharge of
pollutants in
process waste
water
No discharge of
pollutants in
process waste
water
No discharge of
pollutants in
process waste
water
Sulfur!c Acid No discharge of
(Sulfur Burning pollutants in
Contact Process) process waste
water
(1) No water scrubbers for white or Same as BPCTCA
grey aluminum chloride production
(2) For yellow aluminum chloride pro-
duction, gas scrubbing and sale of
scrubber wastes as aluminum chloride
solution; or
(3) Gas scrubbing followed by chemical
treatment to precipitate aluminum
hydroxide and removal by clarification.
(1) Settling pond
(1) Dry dust collection system
Same as BPCTCA
Same as BPCTCA
(1) Acid containment and isolation with Same as BPCTCA
centralized collection of acid wastes;
neutralization to form brines
(1) Acid containment and isolation;
neutralization with lime and
settling ponds
Same as BPCTCA
(1) Evaporation and product recovery; Same as BPCTCA
(2) Recycle to process; or
(3) Ponding and clairification
(1) Storage of bittern in evaporation
ponds; or
(2) Evaporation and recovery of metal
salts
Same as BPCTCA
(1) Storage of wastes in an evaporation Same as
pond; or
(2) Ponding and clarification
(1) Acid containment and isolation
with recycle to process or sale
as weak acid; or
(2) Neutralization with caustic or lime;
and
(3) SC>2 scrubber effluent should be
minimized on existing installation;
and no water-borne wastes from
future SC>2 removal systems
Same as BPCTCA
Same as BPCTCA
Same as BPCTCA
Same as BPCTCA
Same as BPCTCA
Same as BPCTCA
Same as BPCTCA
Same as BPCTCA
Same as BPCTCA
Same as BPCTCA
(continued on next page)
222
-------
TABLE 38. Summary of BPCTCA and BATEA (continued)
Best Available Technology
Chemical
Lime
Nitric Acid
Potassium
(Metal)
Potassium
Dichromate
Potassium
Sulfate
BPCTCA
Guideline
No discharge of
pollutants in
process waste
water
No discharge of
pollutants in
process waste
water
No discharge of
pollutants in
process waste
water
No discharge of
pollutants in
process waste
water
No discharge of
pollutants in
process waste
water
Flow Limitation
liters/kkg kgAkg
TSS Other
Category 2 (TSS Concentration = 25 mg/l;
Calcium
Chloride
(Brine
Extraction)
Hydrogen
Peroxide
(Organic)
Sodium
(Metal)
Sodium
Chloride
(Solution
Mining)
Sodium
Sulfite
330 0.0082 -
16,000 0.40 0.22
TOC
9,000 0.23
6,400 0.15
Best Practicable Control
Technology Currently Available
BPCTCA
(1) Dry Bag Collection System; or
(2) Treatment of scrubber water by
ponding and clarification
(1) Acid containment and isolation
and neutralization
(1 ) No process water used in manu-
facture
(1) Replacement of barometric con-
densers with non-contact heat
exchangers; recycle of process
liquor
(1 ) Evaporation of brine waters with
recovery of magnesium chlorine;
or
(2) Reuse of brine solution in process
in place of process water; or
(3) Ponding and clarification
No Harmful Metals Present)
(1) Settling pond or clarification
(1) Isolation and containment of
process wastes; oil separation
and clarification
(1) Settling pond; and
(2) Partial recycle of brine waste
solution after treatment
(1) Containment and isolation of
spills, packaging wastes,
scrubbers, etc; partial recycle
to brine cavity
630 0.016 1.7*** (1) Air oxidation of sodium sulfite
COD wastes to sodium sulfate -- 94%
(As C^Oj effective; and final filtration to
remove suspended solids
Soda Ash 6,900 0.17
(Sodium
Carbonate)
Solvay Process
(1) Settling ponds
BATEA
Guideline
Same as BPCTCA
Same as BPCTCA
Same as BPCTCA
Same as BPCTCA
economically
Achievable
BATEA
Same as BPCTCA
Same as BPCTCA
Same as BPCTCA
Same as BPCTCA
Same as BPCTCA Same as BPCTCA
Flow Limitation
HtersAkg kg/kkg
TSS
No discharge of
pollutants in
process waste
water
No discharge of
pollutants in
process waste
water
No discharge of
pollutants in
process waste
water
No discharge of
pollutants in
process waste
water
No discharge of
pollutants in
process waste
water
6,900 0.10
Same as BPCTCA
Same as BPCTCA
Same as BACTCA
Same as BPCTCA
Same as BPCTCA
(1) Settling ponds and clarification
(continued on next page)
223
-------
Chemical
Best Practicable Control
BPCTCA Technology Currently Available
Guideline BPCTCA
BATEA
Guideline
Best Available Technology
Economically
Achievable
BATEA
Flow
litersAkg
Limitation
kg/kkg
TSS Other
Category 3 (TSS Concentration = 25 mg/l; Harmful Metals Present)
Hydrogen
Peroxide
(Electrolytic)
95
0.0025 0.002
CNT
0.002
Metals****
Sodium
Dichromate
and
Sodium
Sulfate
8,900
Chlor-alkali
(Diaphragm
Cell)
Chlor-alkali
(Mercury
Cell)
(1) Ion exchange to convert sodium
ferrocyanide to ammonium
ferrocyanide which is then re-
acted with hypochlorite solution
to oxidize it to cyanate solu-
tions; and
(2) Settling pond or filtration to
remove catalyst and suspended
solids
0.22 0.0009 (1) Isolation and containment of
Cr spills, leaks, and runn off; and
0.0044 (2) Batchwise treatment to reduce
Cr (total) hexavalent chromium to trivalent
chromium with NaHS, plus pre-
cipitation with lime or caustic;
and
(3) Settling pond with controlled
discharge
3,300 0.083 0.0025 (1) Asbestos and cell rebuild
Pb wastes are filtered or
settled in ponds then land
dumped; and
(2) Chlorinated organic wastes
are incinerated or land
dumped; and
(3) Purification muds from brine
purification are turned to
salt cavity or sent to
evaporation pond/settling
pond; and
(4) Weak Caustic—brine solu-
tion from the caustic filters
is partially recycled
21,000 0.32 0.0007 (1) Cell rebuilding wastes are
Hg filtered or placed in settling
pond, then used for landfill;
and
(2) Chlorindated organic wastes
are incinerated or placed in
containers and land dumped;
and
(3) Purification muds from brine
purification are returned to
brine cavity or sent to
evaporation/settling ponds;
and
(4) Partial recycle of brine waste
streams; and
(5) Recovery and reuse of mercury
effluent by curbing, insulation
and collection of mercury con-
taining streams, then treatment
with sodium sulfide
No discharge of
pollutants in
process waste
water
(1) Same as BPCTCA plus segregation
of waste water from cooling
water
No discharge of
pollutants-in
process waste
water
(1) Same as BPCTCA
No discharge of
pollutants in
process waste
waster
Same as BPCTCA plus
(1) Extraction/elimination of heavy
metals and impurities from brine
effluent
(2) Installation of dimensionally
stable anodes to replace graphite
in lead anodes
No discharge of
pollutants in
process waste
water
(1) Extraction/elimination of heavy
metals and impurities from all
weak brine solutions
(continued on next page)
224
-------
TABLE 38. Summary of BPCTCA and BATEA (continued)
BPCTCA Best Practicable Control
Technology Currently Available
BATEA
Best Available Technology
Economically
Achievable
Chemical Guideline BPCTCA Guideline BATEA
Flow
litersAkg
Limitation
kg/kkg
TSS Other
Category 3 (continued)
Titanium
Dioxide
(Chloride
Process)
Titanium
Dioxide
(Sulfate
Process)
90,500 2.2
0.036
Fe
0.014
Pb
0.015
Total
Other
(1) Neutralization with lime or
caustic; and
(2) Removal of suspended solids
with settling ponds or
clarifier-thickener; and
(3) Recovery of by-products
Metals;e.g., V, Al, Si, Cr, Mn, Nb & Zr.
100,000 2.5 0.1 Max. (1) Neutralization with lime or
caustic; and
(2) Removal of suspended solids
with settling ponds or clarifier-
thickener; and
Each
Si02,
CrO,
Cr2O3,
AI2Og, (3) Recovery of by-products
& Fe2O3.
2.0MnO Max.
3.2V2O5
Same as BPCTCA
except TSS is
l.SkgAkg
Same as BPCTCA plus additional
clarification and polishing
Same as BPCTCA
except TSS is
1 .5 kg/kkg
Same as BPCTCA plus addition
clarification and polishing
*Monthly average values. To convert from metric units to English units (Ibs/ton), multiply the above values by 2.
**Because three exemplary plants reduce the concetration of suspended solids to less than 15 mg/l, this process is an exception to the
25 mg/l concentration limitation.
***COD of 2720 mg of dichromate ion per liter.
****"Metals" are total dissolved iron and platinum.
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Aluminum Sulfate
Current typical treatment involves use of a settling pond to remove muds
followed by neutralization of residual sulfuric acid prior to discharge.
Two exemplary plants (049 and 063) have closed loop waste-water systems.
Suspended solids are dropped out in the settling vessels and ponds and
the clear overflow returned to the treatment process.
Calcium Carbide
There is no process water involved in the production of calcium carbide.
Ancillary water wastes such as cooling tower blowdowns and ion exchange
regenerants are often present. There may also be water-borne wastes
from air pollution control equipment.
Water-borne wastes from air-borne waste control equipment may be avoided
by use of dry bag collector systems. Unlike aluminum chloride, the air-
borne 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 constitute a significant
fraction of the feed materials, may be profitably returned to the
system. The exemplary plant of this study uses only dry bag collectors
and recycle of collected fines to the furnace.
Dry bag collection of air-borne fines eliminate 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.
Hydrochloric Acid
The only process considered in this study is chlorine burning. Only
about ten percent of the U.S. production comes from this process. Most
hydrochloric acid is produced as a by-product of other processes. The
chlorine-burning process is a simple one and capital equipment is
relatively inexpensive. The process fits well with chlor-alkali
complexes where low-cost or waste chlorine (and possibly hydrogen from
mercury cells) is readily available.
There is no water-borne process waste during normal operation. A small
amount of chlorine and hydrochloric acid wastes is developed during
startup. Neutralization with sodium hydroxide can be followed by
forwarding the neutralized stream to other chlor-alkali complex uses
such as make-up water for brine solutions used in mercury or diaphragm
226
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cells. The size of the waste load, excluding that from the air-borne
hydrogen chloride treatment, is small - 0.5 to 1.0 kg/kkg.
Since there are no process wastes, spills, leaks, contributions from
air-borne hydrogen chloride waste treatment equipment, and startup and
upset wastes are the only concerns. Base treatment and control of these
small miscellaneous wastes consists of neutralization with available
sodium hydroxide followed by discharge to surface water.
To reduce water-borne wastes, containment and isolation techniques are
required. Dikes, dip pans and other devices are used to control leaks
and spills. Centralized collection and neutralization with sodium
hydroxide can be followed by forwarding the neutralized stream to other
chlor-alkali complex uses such as make-up water for brine solutions used
in mercury or diaphragm cells. The size of the waste load, excluding
that from the air-borne hydrogen chloride treatment, is small - 0.5 to
one kq/kkg.
If waste water streams are kept small, as is certainly feasible, control
and treatment costs are minimal.
Hydrofluoric Acid
Hydrofluoric acid sells for approximately $550/kkg. Therefore, the
incentive for containment and recovery of leaks, spills and other
product losses is understandably greater than for the other mineral
acids. By the nature of the process, large quantities or cooling water
are required. This is in the non-contact category, however, such that
water-borne process waste loads are small.
Neutralization of sulfuric and hydrofluoric acid wastes with lime,
followed by removal of precipitated calcium sulfate and calcium fluoride
in settling ponds, reduces fluorides to 18 mg/1 and calcium suifate to
approximately 2000 mg/1 in treated water streams.
Segregation of the leaks, spills and sulfuric acid-containing wastes
from the cooling water reduces the quantity of water which has to be
treated. Also by in-process changes, such as using stoicniometric
quantities of sulfuric acid in the process reactor, the sulfuric acid
may be eliminated from the process waste water stream.
Lime treatment of the isolated wastes and settling pond removal of the
precipitate reduces the fluoride content of this small stream to
approximately 10 mg/1. This procedure gives waste with less than 0.5 kg
total dissolved solids kkg (1 Ib/ton) of hydrofluoric acid. This
227
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treatment makes closed cycle operation possible. Two exemplary plants,
one using once-through cooling water, and the other (plant 152) a closed
cycle system (zero effluent), were found in this study.
There are no air pollution problems for this process, but massive
calcium sulfate solid wastes (34-00-4250 kg/kkg (6800-8500 Ib/ton) of
hydrofluoric acid) from the process reactor give both land disposal and
rainwater runoff problems. Storage piles of this calcium sulfate should
be located and contained so that materials such as calcium sulfate and
residual lime or sulfuric acid are not conveyed by rainwater runoff to
surface or underground fresh water streams.
Calcium Oxide and Calcium Hydroxide
The process for producing calcium oxide involves no water-borne wastes.
Waste water treatment is required only when wet scrubbers are used to
remove entrained dust from the gaseous effluent.
Practices evidently vary from one plant to another as iar as air
pollution control practices are concerned. Some plants have no
facilities for air-borne wastes; other use water scrubbers, others use
dry bag collectors.
Water-borne wastes from air-borne waste control equipment may be avoided
by use of dry bag collector systems. Unlike aluminum chloride, the air-
borne wastes from the calcium oxide process are all dusts. This dust
may be profitably returned to the system. The exemplary plant of this
study uses only dry bag collectors and recycle of collected fines.
Dry bag collection of air-borne fines not only eliminates water-borne
wastes and makes it possible to reuse these fines, but it also
significantly reduces energy requirements by avoiding high energy drying
costs needed for recovery of water wastes.
Nitric Acid
There are no water-borne process wastes. There are usually no water-
borne wastes from air pollution abatement practices. Cooling water
requirements are high. Minor water-borne wastes are due to leaks,
spills and washdowns and ancillary systems such as cooling towers.
Provisions may be made for handling and neutralizing spills and leaks.
Neutralization can be done with limestone, oyster or clam shells, lime
228
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or sodium hydroxide. Collected leaks, spills and washdowns may be
returned to the process.
Diking of tanks, pump areas, loading and washing areas may be combined
with isolation and return of leaks, spills and washdowns. DiKing of
large tanks should be sufficient for complete containment. Emergency
ponds should be provided for major upsets. Limestone or seashell pond
linings and ground coverings may be used for neutralizations.
Potassium Metal
There are no water-borne wastes from this process.
Potassium Chromates
Potassium dichromate is made from the reaction of sodium dichromate with
potassium chloride. There is none of the massive ore waste present as
in the sodium dichromate process. The only water-borne wastes from the
major U.S. production facility emanate from contamination of once-
through cooling water used in the barometric condensers. These are
scheduled for replacement in 1974 by heat exchangers using non-contact
cooling water. This will result in no discharge of waterborne wastes.
Potassium Sulfate
The exemplary plant for production of potassium sulfate is plant 118.
It is a closed cycle plant where water recovery is accomplished by
distillation of 1,500 cu m/day (400 GPD) (somewhat larger than the
sodium dichromate evaporation modelled in Section VIII).
Sodium Bicarbonate
Typical treatment practices involve the settling of suspended solids in
ponds before discharging the effluent to surface waters.
The untreated effluent from this process is essentially sodium carbonate
in solution. In a complex, use for this solution may be made, probably
at lower cost than for recovery. Present waterborne wastes are a
relatively low 6.5 kg/kkg (13 Ib/ton) of product.
By keeping the waste stream small and the solids level high, evaporative
techniques are feasible without undue expense. The evaporation process
yields demineralized water for boilers plus recovered product worth
$36/kkg ($32/ton). An alternative approach would involve total recycle.
Sodium Chloride
In spite of the fact that the sodium chloride industry has very heavy
wastes, disposal is usually accomplished by pumping the brine wastes
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back into the well or mine, by storage of solar salt wastes in large
ponds or by sale of salt wastes. Pond storage is feasible because large
land areas are already available and evaporation-rainfall balances are
favorable in the pertinent areas. Pond storage of bitterns is not a
desirable or economical long range solution for solar salt producers.
The use of the magnesium-rich bitterns for magnesium chemicals
production would conserve major quantities of energy over starting with
natural brines or seawater.
Sodium Silicate
Contaminated waste streams containing sodium hydroxide, sodium silicate
and filter aids may be sent to settling ponds to remove suspended
solids. Waste water is then neutralized and discharged to surface
water.
The wastes from sodium silicate plants are so minor that closed loop
zero discharge operation is feasible.
Sulfuric Acid (Sulfur-Burning and Regen Plants)
There are no process wastes from the sulfur-burning sulfuric acid
plants. The only water-borne wastes result from spills, leaks,
washdowns, and air-borne sulfur dioxide scrubbers.
Leaks, spills and washdowns may be detected by monitoring pH in-
strumentation. In-process leaks give serious corrosion prob
•b'lems so
that shutdown and repair is in order as soon as these leaks are
detected. Neutralization with lime or sodium hydroxide is used to
control the pH level of the effluent.
Emergency ponds may be for containing contaminated cooling water for
neutralization.
Containment, isolation, and reuse or neutralization of minor leaks,
spills and washdowns may be obtained with dikes, catch pans, sumps and
drain systems. Major storage tanks should be sufficiently diked for
complete storage tank capacity containment. Pond linings and pertinent
plant grounds coverings of limestone or seashells can provide automatic
neutralization. pollution devices to remove sulfur dioxide sometimes
contribute to the water-borne waste load. This may be avoided by
utilizing sulfur dioxide removal processes which do not generate waste
water streams. They should be used for all future installations.. These
non-water waste E£ocesses include double-absorption add-ons Ifor
Bl§.Q^§li §Q
-------
Existing sulfur dioxide control equipment which invoves waterborne waste
can be converted to a waste-free basis by concerntration and recovery of
dissolved solids. Since the recovered solid is sodium suliate for which
there is a market, this approach will be analyzed in Section VIII.
Sodium Metal
Sodium metal is produced in a Downs Cell Process. Chlorine, produced
simultaneously with the sodium, is covered in this Section VII under
chlorine. The treatment and control problems for chlorine once it
leaves the cell are the same for the Downs Cell product as ror the
mercury and diaphragm cells chlorine. Therefore, no discussion of
chlorine treatment and control will be made in this subsection.
The non-chlorine based wastes consist of brine purification muds, cell
wastes such as bricks, graphite, sodium chloride and calcium chloride,
and sodium-calcium sludge from the sodium cooling and purification step.
Settling ponds may be used for mud removal. Bricks, graphite and other
solids may be landfilled. Sodium chloride and calcium chloride may be
washed down and allowed to flow to surface water.
In the exemplary plant of this study, (no. 096), the only ceilbased
wastes not land dumped are the sodium and calcium chlorides. These
salts, lost to the extent of an estimated 88 kilograms/kkg of sodium
produced, result from cell dumpings, wash tanks, and run otfs. These
wastes are not currently controlled, and are allowed to run off over the
land into surface water. Isolation and collection would make it
possible to recover and reuse the sodium and calcium chlorides in the
incoming brine system. The simplest procedure would be to recycle this
weak brine into the brine purification system. If this procedure is not
satisfactory, then the fairly small stream can be concentrated to
recover, first any calcium sulfate or sodium sulfate, secondly sodium
chloride, and finally, calcium chloride. Sodium chloride and calcium
chloride can be dumped. Sodium sulfate can be sold or it may be
containerized and disposed of to landfill.
Treatment methods for chlor-alkali facilities to eliminate the discharge
of process waste water pollutants are applicable to chlorine production
using the Downs Cell Process.
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Sodium Sulfite
The wastes from this process are primarily sodium sulfite and sodium
sulfate. The sulfites constitute a heavy chemical oxygen demand (COD).
Typical treatment, at least until recently, has consisted of using large
quantities of cooling water to dilute the waste load.
Best technology is now being applied to effect a ninety-five percent
conversion of sulfite to sulfate by air oxidation.
Recovery of the sodium sulfate from the effluent elimir.a-ces process
waste. This is technologicallyan^ economically feasible. rc-covery reduces
the sulfite process waste to virtually zero and provides ooth a saleable
product and a supply of high quality demineralized water for boiler,
cooling tower, or process use.
Calcium Chloride
This chemical is obtained both from soda ash wastes and from natural
salt deposits. The soda ash produces large amounts of calcium chloride
as a by-product. Unreacted sodium chloride and other dissolved solids
are present in this waste stream. After calcium chloride is extracted
from this waste stream, the remaining calcium chloride, sodium chloride
and other dissolved solids may be returned to the waste stream of soda
ash manufacture. Extraction of calcium chloride from natural salt
deposits is carried out in a major chemical complex and is scheduled
within the next six months to be brought to virtually a zero process
waste water pollutant discharge. Since both processes are dissimilar,
there are no typical practices. The two major producers differ widely
in their treatment approach.
From the soda ash process, recovery of calcium chloride is considered as
a zero discharge process similar to sodium sulfate from the sodium
dichromate process. There are no additional wastes generated as a
result of this recovery.
The natural salt process, on the other hand, utilizes the integrated
nature of the complex where it is produced to take advantage of every
normal waste. Sodium chloride goes to chloralkali facilities.
Magnesium chloride, which is often difficult to dispose of, is isolated
and used for other processes. Consequently this process for making
calcium chloride also has no effluent in the particular complex where it
is made. This is a good example of the previously discussed principle
that wastes from a complex should never be greater than the sum of the
individual plants and usually will be significantly less.
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Hydrogen Peroxide (Organic Process)
The organic process effluent generally contains waste hydrogen peroxide-
plus organic solvent used in the process. The nature of this solvent is
considered a trade secret.
The hydrogen peroxide waste may be decomposed with scrap iron. The
organic solvent may be removed by skimming the insoluble layer off the
top of the water stream. The effluent may then be passed into a
settling pond for removal of suspended solids or organic solvent
interaction with suspended solids from other processes. Additional
isolation, containment and treatment of wastes with scrap iron for
oeroxides and skimming separation for organics further reduces trie wast-?'
loads.
Organics may be removed from this waste water stream by oiological
digestion as commonly used in sanitary sewage treatment. Ta- wast^
water could be sent, directly to a municipal sewer without problem.
An alternate technigue is to remove the organics by carbon absorption.
Sodium Carbonate
The Solvay Process for making sodium carbonate (soda ash) is an old one
dating back to the late 1800's. The Solvay plants are also old, the
last U.S. plant being built in the 1930's,
The Solvay Process discharges more poundage of waste into surface water
(solid basis) than any other chemical of this study (sodium chloride
producers deep-well or store most of their effluent). The only
redeeming feature is the relatively low toxicity of the waste.
Present treatment of water-borne wastes consists of removing most of the-
suspended calcium carbonate and other solids in unlined settling ponds
followed by discharge to surface water. Adjustment for pH may or may
not be done prior to this discharge.
The water-borne wastes from the Solvay Process are suspended and
dissolved solids. The suspended solids are removed effectively by
settling ponds and polish filtering can be done if necessary to reduce
total suspended solids levels to 25 mg/1.
Dissolved solids are another matter. There are extensive treatment
technologies available which can be used to eliminate the dissolved
solids from the water effluent but most of them are not economically
practical for the Solvay Process. Also, the geographical location of
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the plant has a major bearing on the treatment and disposal feasibility
and costs.
A new plant of the Solvay Process is very unlikely to be considered. If
a new Solvay Process plant were to be built, the process itself would
likely be revised. Process modifications now in the laboratory or pilot
plant stages would have to be investigated and developed for commercial
feasibility. The major area of revision would be in the recovery of
ammonia from ammonium chloride. Use and recovery of magnesium hydroxide
or decomposition of ammonium chloride to ammonia and chlorine are two
such modifications that have been proposed. Recovery and reuse of the
excess sodium chloride in the waste effluent could be accomplished by
evaporation and crystallization techniques similar to those for the salt
industry.
Sodium Bicarbonate (as part of the Soda Ash Complex)
Sodium bicarbonate is made by a simple, low-waste process. Its effect
is similar to isolated solvay plants in this case since there is no
effective general way to reduce Solvay Process wastes.
Chlorine is produced by three major processes: mercury cells, diaphragm
cells and Downs Cells. The other chemicals produced are sodium (Downs
Cell only), sodium hydroxide and potassium hydroxide, variously. There
is also quite often a direct burning hydrochloric acid plant in the
complex.
The following chlorine discussion include mercury and diaphragm cell
productions. Downs Cell operation will be discussed under sodium, but
the chlorine-based wastes are the same as for the mercury and diaphragm
cells.
The chlor-alkali industry uses salt (sodium chloride or potassium
chloride) as its raw material. Transformations of all sodium and
chlorine chemicals can and have been made in chlor-alkali plants. There
is a fortunate situation from the standpoint of waste reduction and zero
discharge. In contrast, for example, are the soda ash process which
produces large quantities of calcium chloride for which no use can be
made and the potassium dichromate process which produces large
quantities of sodium chloride with no use for it in the process.
Examples of how waste conversions can be made in the chlor-alkali
process are given in the following equations:
(1) 2NaCl -* 2Na + C12
(2) 2Na + 2H2O -*> 2NaOH + H2
(3) 2NaOH + C12 —~ NaOCl + NaCl + H20
(U) 2NaOCl + Cat. —»• 2NaCl + O2
(5) C12 + H2 -+ 2HC1
(6) HC1 + NaOH -* NaCl + H20
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Equations (1) and (2) show the product formations. Equation (3)
represents tail gas scrubbing operations to remove chlorine gas from air
effluents from the plants. Equation (4) shows conversion of sodium
hypochlorite back to salt raw reactant materials. Equation (5)
eliminates waste chlorine gas by direct burning of chlorine to produce
hydrochloric acid. Equation (6) uses hydrochloric acid to neutralize
waste sodium hydroxide, thereby producing salt for return to the system.
Provided the water-borne waste streams are kept isolated rrom much
larger cooling water streams, control and treatment techniques are
entirely feasible.
Salt impurities have to be removed by precipitations before the brine
solutions can be used in the cells. Treatment with soda ash, sodium
hydroxide, and sometimes barium chloride, removes calcium, mcignesium and
sulfate ions as calcium carbonate, magnesium hydroxides and barium
sulfates, respectively. The precipitated muds may be removed in ponds
or clarification tanks. The muds may be disposed of by icind dumping or
fill.
Brine and sulfuric acid wastes may be neutralized with lime or sodium
hydroxide, and ponded for reduction of suspended solids.
Water-borne mercury in the mercury cell process may be treated and
removed by a variety of processes, usually employing precipitati or of
mercury sul fides, followed by mercury recovery by roasting or chemical
treatment processes. Plants with typical recovery systems reduc^
mercury in the plant effluent to 0.11 to 0.22 kg/day (0.25-0.50 lo/day) .
waste reduction depends on in-process control, isolation,
reatment and reuse. There is no known problem which has not be^n
solved by at least one plant of this survey.
Mercury cells are inherently "cleaner" processes than the diaphragm
cells. Diaphragm cells have asbestos diaphragm deteriorations with
suspended asbestos wastes. These have to be filtered out or allowed to
settle in ponds. Sodium hydroxide produced in diaphragm cells has
sodium chloride and other wastes and has to be purified for many uses.
A sodium sulfate purge, made by back-washing the precipitated salt
slurry on the filter during the evaporation concentration of sodium
hydroxide, is also needed to ensure satisfactory diaphragm cell
operation. This sulfate purge can be handled by removing it from the
system and using it elsewhere (as is done by exemplary diaphragm cell
plant 057) , elsewhere (as is done by exemplary diaphragm cell plant
057) , by returning it for sulfate removal in the brine purification, or
by recovery of sodium sulfate for sale.
235
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Another waste from the diaphragm process, but not the mercury cell, is
organic waste from the graphite anode. These are currently land
disposed by the exemplary diaphragm cell plant, but are allowed to go
out in waste streams at others.
Waste sulfuric acid from the chlorine-drying step may be used for
neutralizations in other processes, sale, shipment to a regen sulfuric
acid plant, concentration, or at worst it can be neutralized with lime
or sodium hydroxide.
Collected chlorine gas for abatement of air-borne wastes can be burned
to produce hydrochloric acid or converted to sodium chloride as
discussed earlier.
Diaphragm cells are prone to develop cracks around their anode
protective resin seals and lead salts from the underlying lead mountings
can get into the effluents. Dimensionally stable anodes can eliminate
this problem and at a reported significant reduction in required cell
electrical energy load.
The mercury cell, although "cleaner" than the diaphragm process, has a
major waste problem in the form of mercury in the water-borne wastes.
Major expenditures (discussed more quantitatively in Section VIII) and
in-process modifications have been made to alleviate this problem. The-
best plants today are capable of mercury levels of 0.045 to 0.11 kg/day
(0.1-0.25 Ib/day) of waterborne mercury content. These low levels are
accomplished by isolation of mercury-containing waste streams and
chemical treatment of these streams. costs have been high for this
cleanup.
Although no specific mention has been made of potassium hydroxide
production, the same principles hold except that potassium is
substituted for sodium.
By employing extensive treatment, control, recycle, and recovery, the
chlor-alkali process may be operated with no discharge of process waste
water pollutants to navigable waters.
Hydrochloric Acid (in Complexes)
The only difference between isolated hydrochloric acid plants and ones
in chlor-alkali complexes is that flexibility of treatment, control and
disposal of wastes is enhanced. Therefore, waste loads which should be
the same in both situations, are lower in the complex. The principle
followed throughout treatment and control sections, particularly Section
VIII on costs, is that each chemical process has inherent wastes
isolatable from other processes. This approach makes it simple to
calculate maximum waste loads from complexes merely by adding individual
236
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plant wastes per ton of production. Expected loads for each complex may
be determined specifically from interactions possible^
Sodium Hydroxide
Discussed under chlorine.
Potassium Hydroxide
Discussed under chlorine.
Hydrogen Peroxide (Electrolytic)
The electrolytic process for making hydrogen peroxide is represented by
a single U.S. plant (100). Its effluent has practically the same
composition as the incoming water, because the relatively very small
amount of process water discharged is combined with the very large
cooling water stream. Present levels were accomplished by in-process
controls. The total water flow into the plant is about 41,600 cu m/day
or 3,470,00 1/kkg (11,000,000 gal/day or 11,000,000 gal/ton). 75.7 cu
m/day or 6300 1/kkg (20,000 gal/day or 1830 gal/ton) is treated by ion
exchange and used for boiler feed and process water. Discharges of this
treated wtate includes 3.8 cu m/day or 316 1/kkg (1000 gal/day or 92
gal/ton) of ion exchange blowdown, 26.5 cu m/day or 2200 1/kkg (7000
gal/day or 640 gal/^on) of boiler blowdown and 1.1 cu m/day or 95 1/kkg
(290 gal/day or 27.6 gal/ton) of process water effluent. This latter
stream may be eliminated by simple procedures such as total evaporation
which is economically feasible because of the small quantity.
Sodium Dichromate
Typical treatment is to reduce the hexavalent chromium ion in the waste
to trivalent chromium, remove the suspended solids in a settling pond,
and discharge the clear solution to surface water. Ferrous chloride is
often used as a reducing agent.
An exemplary chromium treatment and control plant (184) includes
isolation of all chromium-containing, water-borne wastes from cooling
water, collection of these wastes in tanks, batchwise treatment for
hexavalent chromium reduction, and pond settling of suspended solids.
The hexavalent chromium content remaining after treatment is very low.
Provision is made in this plant for collection and treatment of
rainwater (important in chemical plants handling harmful materials).
Batchwise treatment and analysis before discharging provides good
control.
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Although the treatment and control technologies described above are
excellent for Chromium treatment and control, two environmental problems
remain -- disposal of large quantities of solids which gradually fill
the settling ponds and discharge of large quantities of dissolved sodium
chloride into surface water. The settled solids can be landfilled and
the sodium chloride can be recovered by evaporation techniques and sold.
The evaporative approach is economically and technically feasible.
There are ether technologies available for chromium removal.
Sodium Sulfate (By-Product)
Sodium sulfate is a relatively pure by-product from the manufacture of
sodium dichromate and other processes. As such, it has no water-borne
wastes and there is no treatment and control technology applicable,
except as applied to the sodium dichromate process itself.
Titanium Dioxide (Sulfate Process)
The sulfate process for producing titanium dioxide has the greatest raw
waste load of all the processes of this study. Approximately 2,000 kg
of sulfuric acid and 1,000 kg of metallic sulfates/kkg of product have
to be discarded. Low grade ores used in the process contribute major
quantities of metals which may someday be profitably extracted.
Waste streams generated by the sulfate process include:
(1) sludge from the dissolving step and filtration,
(2) copperas,
(3) strong acid cuts,
weak acid cuts, and
titanium dioxide losses.
Wastes may be collected and sent to a settling pond for suspended solids
removal.
The sulfate process for titanium dioxide was one of the few for which no
exemplary plant was found. This is not because . control and treatment
technology is lacking, but rather because it is more economical not to
apply it. The exemplary treatment and control process involves
filtration and disposal of the sludge from the dissolving step by land
dumping, neutralization of both strong and weak acid cuts with
limestone, followed by lime treatment to raise pH to approximately 8 and
precipitate iron and other metallic oxides and hydroxides. The
conventional chemical treatment system of neutralization tanks,
clarifiers, thickeners, filters or centrifuges and ponds may be employed
for this purpose. This treatment reduces the waste load discharge to
solubility limits of calcium sulfate.
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Ocean barging of the strong acid wastes, sludges and metallic sulfates
is now used for disposal. Uncertainty about the future of this disposal
method currently clouds its general application. Also, the weak acid
and other wastes are still in many cases being discharged to surface
water without significant treatment.
Recovery of the strong sulfuric acid in the sulfate process waste load
has been practiced in the past. Whether this recovery was abandoned for
technical or economic reasons is not known. A pilot New Jersey Zinc
Company with contract assistance from EPA. Acid recovery is accompanied
by treatment of the weak acid, metallic sulfates and titanium dioxide
losses in the same type of chemical treatment system as discussed for
complete neutralization. Acid recovery reduces the soliu waste load
inherent with complete neutralization approximately two-to-threo fold
and also decreases the amount of water-borne wastes. Costs likewise
favor this approach over complete neutralization. The shortcoming for
acid recovery processes is that they are either still in the development
staae or are captive technology not being used currently.
Titanium Dioxide (Chloride Process)
The titanium dioxide industry is in a state of flux. Rutile is in a
very short supply and most chloride process producers need this ore or a
synthetic version of it. "Synthetic Rutiles", or beneficiated low grade
ores, are being offered by various foreign and a few domestic suppliers.
Ishihara of Japan has operated a 27,000 kkg (24.6 ton) plant since 1971
and is expanding to 40,000 kkg (36.4 tons) by October 1973. Sherwin
Williams has announced a proposed 45,000 kkg/yr (41,000 ton/yr) plant
using Australian technology. A comprehensive discussion of ore
deposits, their composition, and beneficiation techniques may be found
in Dr. Thomas S. Mackey's article "Alteration and Recovery of Ilmenite
and Rutile", Australian Mining, November 1972, pp. 18-94. "Synthetic"
Rutiles" offer the opportunity to eliminate most of the ore dross and
undesired metallic oxides in sites more suited for this purpose than
most present titanium dioxide plants.
Chloride process plants, by the nature of the process and the ore used
(90-96 percent titanium dioxide), usually have less other low grade ores
and have a corresponding heavier waste load than the rutile-using
chloride process plants.
Waste streams for the chloride process fall into two categories:
1. Chlorination wastes composed of sludge from titanium tetrachloride
losses and
2. Wastes incurred during the oxidation process and treatment of
titanium dioxide product.
239
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Base level treatment usually includes ponding to remove titanium
dioxide, ore, coke and other settleable solids.
Three techniques for more effective treatment or disposal of chloride
process wastes are available; neutralization of acids and conversion of
metallic chlorides to insoluble oxides, ocean barging and deep welling.
A full chemical treatment system similar to that described elsewhere in
this section is used in exemplary plant 009. Chemical neutralization
tanks, a clarifier, a thickener, and filters followed by a pond system
are used for full acid neutralization, conversion and precipitation of
metallic oxides, and concentration of suspended solids into a sludge.
The sludge is disposed of as land fill. Both of the main chloride
process waste streams, chlorination solids and oxidation process and
titanium dioxide product-treatment wastes, are put through the chemical
treatment system. The water-borne wastes from the system consist
primarily of dissolved calcium chloride.
Deep welling of the chlorinated wastes is practiced by a second
exemplary plant, no. 160. The oxidation and titanium dioxide product
treatment wastes are sent through a settling pond system and discharged
to surface water. Such deep well disposal is not a general solution to
waste abatement practices, since it is not geologically feasible in many
sections of the country. Ocean barging is also used to dispose of
chloride process wastes. This disposal technique also can not be used
generally since some of the chloride process plants are not accessible
to the oceans. Both of these disposal techniques are subject to
stringent permit requirements.
The major chloride process wastes, particularly when low grade ore is
used, are ferrous and ferric chlorides. Various proposals have been
made for disposing of these chlorides. Included in these proposals are
processes for decomposing the iron chlorides to iron oxide and
hydrochloric acid (favored for pickle liquor recovery) , a process for
oxidation of iron chlorides to iron oxides and chlorine, and sale of the
iron chlorides as such. Beneficiation of ore by chlorination,
separation of iron chlorides, and dechlorination of the iron chlorides
is another procedure. All of the above are still in the exploratory,
laboratory, pilot plant or other preliminary stage at this time. Bureau
of Mines research is already being carried out. Undoubtedly there are
industrial efforts along similar lines. Further discussion of these and
other waste abatement practices may be found in Section VIII where rough
cost estimates are included.
240
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GENERAL METHODS FOR CONTROL AND TREATMENT PRACTICES IN THE INDUSTRY
Control and treatment technology for water-borne wastes from th?
inorganic chemicals industry needs to be approached from a chemical and
chemical engineering viewpoint rather than classical sanitary
engineering practices. Organic content and biological oxygen demands of
the effluents are usually very low and not a significant factor. Tn
fact, most of the involved control and treatment technology is v,7?ll
known, established and extensively practiced in the process of producing
the inorganic chemicals cf this study. Practices such as chemical
treatment (neutralization, pH control, precipitation, and chemical
reactions), filtration, centrifuging, ion exchange, demineralization,
evaporation and drying are all standard unit operations for the
industry. Process instrumentation, monitoring and control for the
chemical industry is outstanding. Unfortunately, all too often, the en-
gineering and technological excellence used throughout the process does
not extend to waste treatment and control. Another characteristic of
the waste effluents from the inorganic chemical plants of this study is
that they differ widely in both chemical nature and amount (see Table
39) . Soda Ash (Solvay) and titanium dioxide (sulfate process) have raw
waste loads in excess of the amounts of chemicals produced. On the
other hand, chemicals such as the mineral acids, calcium carbide ar?d
aluminum chloride have almost no water-borne wastes. Soda ash (Solvay)
wastes are neutral salts while titanium dioxide (sulfate process) wastes
are strongly acidic.- Therefore, control and treatment technology has to
be applied differently for each chemical.
typical control and treatment technology in use on inorganic waterborne
wastes today includes neutralization and pH control on effluent streams,
ponds for settling of suspended solids, emergency holding, and storage,
ani discharge of the neutralized and clarified effluent to surface
water.
Discharge of acidic or alkaline wastes to surface water is uncommon and
is becoming more so all the time. Harmful wastes such as mercury,
arsenic, cyanides, chromium and other metals are Deing removed with
increasing efficiency. Technology has been developed for reduction of
these harmful materials to very low levels. In exemplary plants,
specified or acceptable water quality levels are being met.
There were many instances, during this study of exemplary plants, of
conscientious and successful waste abatement programs. Profitable waste
segregations and recoveries, closed cycles, leak and spill containments,
and in-process waste reductions are commonplace. Some of these waste
abatement programs have not involved much money, but most have been
expensive. Numerous plants have reported program costs ranging from
several thousand to several million dollars. In many cases air
pollution abatements involve more capital outlay than water treatment
costs.
Waste abatement for the inorganic chemicals industry may be accomplished
by a variety of methods. These methods may be divided into control and
24]
-------
containment practices and treatment techniques. In many cases the
control and containment practices are more important than subsequent
treatments as far as feasibility and costs of waste treatment are
concerned. The reasons for this are discussed in the following
sections.
In-process controls
Control of the wastes includes in-process abatement measures, monitoring
techniques, safety practices, housekeeping, containment provisions and
segregation practices. Each of these categories is discussed including
the interactions with treatment techniques.
242
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TABLE 39. Typical Water-Borne Loads for
Inorganic Chemicals of this Study
Chemical
Sodium Chloride
Soda Ash (Solvay)
Titanium Dioxide (Sulfate)
Chloride (Non-Rutile)
Chloride (Rutile)
Chlorine-Sodium Hydroxide
Sodium
Sulfuric Acid
(Sulfur Burning)
Sodium Dichromate
Sodium Silicate
AluminumSulfate
Nitric Acid
Hydrogen Peroxide
Hydrofluoric Acid
Sodium Bicarbonate
Aluminum Chloride
Sodium Sulfite
Calcium Carbide
Hydrochloric Acid
(Direct Burnina)
Annual
Production
kkg
39,000,000
3,630,000
374,000
186,000
64,000
8,600,000
150,000
27,200,000
136,000
601,000
1,020,000
6,300,000
64,000
281,000
186,000
31,000
209,000
834,000
200,000
Waste Load*
kg/kkg Total Waste*
kkg/yr
Product
150
1,500
5,000
400
75
150
150
0.5
58
7.5
3.5
0.25
20
4
4.5
24
3
0.5
0.5
5,850,000
5,440,000
1,870,000
744,000
4,800
1,300,000
22,500
13,600
13,600
4,500
3,570
1,590
1,270
1,120
840
725
625
415
100
NOTES:
1) Production figures were taken from Chem. 8 Eng. News,
May 7, 1973, pp. 8-9 and "The Economics of Clean Water",
Vol. Ill, Inorganic Chemicals Industry Profile, U.S. Dept.
of the Interior, Federal Water Pollution Control Admin.,
March, 1970.
2) Typical waste loads were estimated from Final Technical
Report, Contract No. 68-01-0020, Industrial Waste Study
of Inorganic Chemicals, Alkalies and Chlorine, General
Technologies Corp., July 23, 1971 (for EPA).
3) Titanium dioxide industry production figures were esti-
mated from Chem. & Eng. News, February 19, 1973, pp. 8-9.
*Solids basis.
243
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Raw materials
Purity of the raw materials used in the manufacturing process influences
the waste load. Inert or unusable components coming into the process
are discharged as waste. Economics and availability, however,
necessitate use of impure ores and technical grade reactants.
Control of these impurities can be exercised in many instances. Ores
can be washed, purified, separated, beneficiated or otherwise treated to
reduce the waste coming into the process. An important facet of this
approach is that this treatment can often be done at the mining site
where such operations can be contained or handled on the premises
without polluting effluents. Reduction of shipping charges also favors
beneficiation at the mine. Sometimes, as for "synthetic rutile" used in
the titanium dioxide chloride process, beneficiated or high quality ore
is necessary for developed process technology. Economics of raw
material purity need to be balanced against the attendant waste
treatment and disposal costs. As waste costs change, it ma'y become more
economical to use high quality materials.
Although pure raw materials reduce the inherent waste load, there are
instances where, aside from economic factors, it may be desirable to use
an impure material. In large manufacturing complexes, wastes from one
process may be used for useful purpose in another. This procedure not
only eliminates a bothersome waste from one process, it also gives
economic value in the other. An example is the use of spent sulfuric
acid in decomp plants. Recycled raw materials serve the same desirable
function.
Reactions
Except in ,rare cases such as the mining of salt or soda ash (Trona),
chemical reaction is involved in the manufacture of inorganic chemicals.
Sometimes the reactants are stoichiometrically involved, but more often
than not an excess of one or more of the reactants is used. The
purposes of the excess vary but include: 1. certainty that the more
expensive reactants are completely utilized; 2. yield improvement by
driving the reaction in the desired direction; 3. safety concerns where
it is imperative a given reactant be eliminated; 4. shortening reaction
time.
Excess reactants must be recovered for recycle or else they become part
of the waste load. Often when the cost of the excess reactants was
small, it had been more economical to let them go into the waste load
rather than recover them. Sodium and calcium chlorides and sulfates are
among the most common materials so handled.
Reactions may often be made to operate at more nearly stoichiometric
conditions and thereby reduce waste loads. Also, the waste load may be
deliberately changed in many cases by changing the reactant ratio. In
244
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the burning of hydrogen and chlorine to form hydrogen chloride,
operating on the chlorinerich side provides more troublesome waste than
operating on the hydrogen-rich side. Similarly, aluminum chloride made
on the chlorine-rich side requires air scrubbing to remove excess
chlorine, while the aluminum-rich side does not.
Many chemical reactions are either faster and more complete at high
temperatures or are exothermic and generate high temperatures. To
produce, control and/or reduce these temperatures, cooling water and
steam are often used. If the water or steam is used without contact
(such as in a shell and tube heat exchanger) , it is not contaminated.
If, however, the water or steam contacts the reactants, then
contamination of the water results and the waste load increases.
Therefore, reaction heating and cooling should be non-contact whenever
feasible.
Separations, purifications and recoveries
.After reaction, the products, by-products, impurities, inerts and other
materials present need to be separated, purified and recovered.
Separations are carried out exploiting differences in boiling points,
freezing points, solubility and reactivity to separate products from
impurities, by-products and wastes. The efficiency of these determines:
1. the fraction of product that is lost as waste or has to be recycled;
2. the purity of the product; 3. control of air pollutants; U. the
recovery and/or disposition cf by-products and wastes.
The more complete the separations into recovered product, raw materials
that can be recycled, and wastes, the smaller the waste load rrom the
process. The degree of separation actually achieved in the process
depends on physical, chemical and economic considerations. These
effects will be discussed for the individual chemicals of this study as
they apply.
Cooling water and steam are also used in large quantities in the
separation and purification steps. The same concepts apply as discussed
in the reaction section. Indirect heating and cooling may, in many
instances, virtually eliminate waterborne wastes.
Segregation
Probably the most important waste control technique, particularly for
subsequent treatment feasibility and economics, is segregation.
Incoming pure water picks up contaminants from various uses and sources
including:
1. non-contact cooling water
2. contact cooling water
3. process water
U. washings, leaks and spills
5. incoming water treatment
6. cooling tower blowdowns
7. boiler blowdowns
245
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If wastes from these sources are segregated logically, their treatment
and disposal may sometimes be eliminated entirely through use in other
processes or recycle. In many instances, the treatmenr costs,
complexity and energy requirements may be significantly reduced.
Unfortunately, it is a common practice today to blend small, heavily
contaminated streams into large non-contaminated streams such as cooling
water effluents. Once this has been allowed to happen, treatment costs,
energy requirements for these treatments, and the efficient use of water
resources have all been comprised. In general, plant effluents can be
segregated into: 1. Non-contaminated cooling water. Except for leaks,
noncontact water has no waste pickup. It is usually high volume. 2.
Process Water. Usually contaminated but often small volume. 3.
Auxiliary Streams. Ion exchange regenerants, cooling tower blowdowns,
boiler blowdowns, leaks, washings - low volume but often highly
contaminated.
Although situations vary, the basic segregation principle is don't mix
large uncontaminated cooling water streams with a smaller contaiminated
process and auxiliary streams prior to full treatment and/or disposal.
It is almost always easier and more economical to treat and dispose of
the small volumes of waste effluents - capital costs, energy
requirements, and operating costs are all lower. The use of segregation
will be discussed for individual chemical processes.
Monitoring techniques
Since the chemical process industry is among the leaders in
instrumentation practices and application of analytical techniques to
process monitoring and control, there is rarely any problem in finding
technology applicable to wastewater analysis.
Acidity and alkalinity are detected by pH meters, often installed for
continuous monitoring and control.
Dissolved solids may be estimated by conductivity measurements,
suspended solids from turbidity, and specific ions by wet chemistry and
colorimetric measurements. Flow meters of numerous varieties are
available for measuring flow rates.
The pH . meter is the most universal of the in-line monitoring
instruments. In acid plants, hydrochloric, sulfuric, phosphoric,
nitric, hydrofluoric, and chromic acid leaks in coolers, distillation
columns, pumps and other equipment can be picked up almost at once.
Spills, washdowns and other contributions also become quickly evident.
Alarms set off by sudden pH changes alert the operators and ofren lead
to immediate plant shutdowns or switching effluent to emergency ponds
246
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for neutralization and disposal. Use of in-line pH meters will be giv^n
additional coverage in the control and treatment sections for specific
chemicals.
Monitoring and control of harmful materials such as chromates, batch
techniques are used. Each batch is analyzed before dumping. This
approach provides absolute control of all wastes passing through the
system. Unless the process is unusually critical, dissolved solids are
not monitored continuously. This follows from the fact that most
dissolved solids are rather innocuous. Chemical analyses on grab or
composite effluent samples are commonly used to establish total
dissolved solids, chlorides, sulfates and other low ion concentrations.
Safety, housekeeping containment
Many of the chemicals of this study or their wastes are either harmful
and/or corrosive. Examples are the acids, chromates, chlorine, sodium
hydroxide, sodium, and potassium. Mercury from chlor-alkali plants is
an example of a harmful waste. Containment and disposal requirements
may be divided into several categories: 1. minor product spills and
leaks 2. major product spills and leaks 3. upsets and disposal failures
U. rain water runoff 5. pond failures
Minor spills and leaks
There are minor spills and leaks in all industrial inorganic chemical
manufacturing operations. Pump seals leak, hoses drip, washdowns of
equipment, pipes and equipment leak, valves drip, tank leaks occur,
solids spill and so on. These are not going to be eliminated. They can
be minimized and contained. In some cases the products are valuable
(such as hydrofluoric acid and titanium dioxide where every pound lost
is like throwing a quarter down the drain). In other cases, where the
financial loss may not be as great, personnel safety and equipment
corrosion may become paramount. When a leak develops in the heat
exchanger of a sulfuric acid plant, the plant shuts down before
corrosion gets out of hand. Also, phosphorus is not handled carelessly.
Reduction techniques are mainly good housekeeping and attention to sound
engineering and maintenance practices. Pump seals or type of pumps are
changed. Valves are selected for minimizing drips. Pipe and equipment.
leaks are minimized by selection of corrosion-resistant materials.
Containment techniques include drip pans under pumps, valves, critical
small tanks or equipment, and known leak and drip areas such as loading
or unloading stations. Solids can be cleaned up or washed down. All of
these minor leaks and spills should then go to a containment system,
catch basin, sump pump or other area that collects and isolates all of
them from other water systems. They should go from this system to
suitable treatment facilities.
247
-------
The above mentioned techniques are being used effectively in a number of
exemplary plants today, and in many cases with enhanced profitability.
Major product spills and leaks
These are catastrophic occurrences with major loss of product — tank
and pipe ruptures, open valves, explosions, fires, earthquakes.
No one can predict, plan for or totally avoid these happenings; but they
are extremely rare. Probably the most common of these rare occurrences
is tank or valve failures. These can be handled by adequate dikes able
to contain the tank volume. All acid, caustic or toxic material tanks
should be diked to provide this protection. Other special precautions
may be needed for flammable or explosive substances.
Upsets and disposal failures
In many processes there are short term upsets. These may occur during
startup, shutdown or during normal operation. These upsets represent a
very small portion of overall production but they nevertheless
contribute to waste loads. Hopefully, the upset products may be
treated, separated, and largely recycled. In the event that this can
not be done, they must be disposed of. Disposal failures require
emergency tanks and/or ponds or some other expediency for temporary
holding or disposition. Deep wells should have either a back-up well in
case of original well failure or an alternate method of disposal. Ocean
barges for bad weather interruptions or barge damage or maintenance
should also have temporary storage and/or treatment facilities. Failure
to provide sufficient back-up temporary alternative treatment and
disposal facilities was one of the most frequent shortcomings of plants
visited.
Rainwater runoff
Another area of concern is the pickup of suspended or dissolved wastes
in rainwater runoff frcm the property.
There are a few areas where concern is warrented. Examples are: the
large gypsum piles at hydrofluoric acid plants, chromate plants with
poor housekeeping and some mercury cell chlorine plants. Any potential
problems, such as for chromates, can usually be minimized by good
housekeeping and containment practices in the plant area (as discussed
in a previous section). Minimizing airborne wastes, which settle as
dusts and mists on buildings and grounds, also reduces rainwater pickups
and surface water contaminations.
Pond failures
Unlined ponds are the most common treatment facility used by the
inorganic chemical industry. Failures of such ponds occur because they
248
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are unlined and because they are improperly constructed for containment
in times of heavy rainfall.
Unlined ponds may give good effluent control if dug in impervious clay
areas or poor control if in porous, sandy soil. The porous ponds will
allow effluent to diffuse into the surrounding earth and water streams.
This may or may not be detrimental to the area, but it is certainly poor
waste control. Lined ponds are the only answer in these circumstances.
Many ponds used today are large low-diked basins. In times of heavy
rainfall, much of the pond content is released into either the
surrounding countryside or, more likely, into the nearest body of water.
Again, whether this discharge is harmful or not depends on the effluent
and the surrounding area, but it does represent poor effluent control.
Good effluent control may be gained by a number of methods, including:
1. Pond and diking should be designed to take any anticipated rainfall -
smaller and deeper ponds should be used where feasible.
2. Control ponds should be constructed so that drainage from the
surrounding area does not inundate the pond and overwhelm it.
3. Substitution of smaller volume (and surfaced) treatment tanks,
coagulators or clarifiers can reduce rainfall influx and leakage
problems.
Treatment and Disposal Methods
After the in-process control practices discussed in the previous section
have been utilized, treatment is usually required for the contaminated
streams. In general, these streams may be divided into one of three
categories: cooling water, process water, and ancillary water.
Cooling water, either once-through or recycled by means of a cooling
tower, should be relatively free of wastes. Any contaminants present
would come from leaks (stream to be sent to emergency pond as soon as
control monitoring picks it up) or recycle buildups (cooling tower)
which are handled as ancillary water blowdownSi In either event, cool-
ing waste contributions are small and treatment, except for incoming
water purification, should not normally be needed.
Process and ancillary waterborne wastes do require treatment. The type,
degree and costs involved will depend upon specific circumstances unique
for each chemical:
Small settling ponds or vessels Minor filtrations Minor chemical
treatments Ion exchange (low TDS) Settling ponds or vessels Major
filtrations Chemical treatments Centrifuging Drying Carbon adsorption
Lower cost treatments apply to both incoming and waste water streams.
Incoming surface water from streams, lakes, or ocean is often subjected
to filtration to remove suspended objects and solid particles, minor
249
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chemical treatments for clarification (small suspended solids particle
removal), pH control, and chlorination for BOD control. Ion exchange is
used to replace undesirable calcium, magnesium, carbonate and other ions
which plate out on boiler, water tower and process equipment as they are
concentrated, aerated or subjected to pH changes.
Waste water streams are often subjected to filtrations to remove minor
suspended solids. Screens, cloths, cartridges, bags, candles arid other
mechanisms are used. Driving force may be gravity, pressure or vacuum.
Usually the filters are precoated with diatomaceous earth or other
filter aids.
Minor chemical treatments on waste water streams include neutralizations
for pH control, equalization of streams in a pond or tank to smooth out
waste composition fluctuations, and chemical reactions or precipitations
to remove undesired components.
Settling ponds or vessels are the major mechanism used for reducing the
suspended solids content of water waste streams coming from the plant.
Their performance and cost depends on the amount of waste involved and
the settling characteristics of the solids suspended. In the lower cost
category they are small, reflecting either fast settling and/or small,
flow rates.
Costs for the above treatments may in some cases be derived in the
following sections as extrapolations.
Higher cost treatments are rarely needed for incoming water (except in
cases where either only very poor quality water is available or very low
TDS is required). They are more applicable for treating waste
effluents.
Ion Exchange and Demineralizatipns
Ion exchange and demineralizations are usually restricted in both
practice and costs to total dissolved solids levels of 1000 to 4000 mg/1
or less. Table 40 gives water compositions as a function of water
treatments, including ion exchange and demineralization.
An ion exchanger may be simply defined as an insoluble solid electrolyte
which undergoes exchange reactions with the ions in solution. An
exchanger is composed of three components: an inert matrix, a polar
group carrying a charge and an exchangeable ion carrying an opposite
charge. The inert matrix today is usually cross-linked polymeric resin
containing the needed polar groups.
There are two types of ion exchangers: cation and anion. Cation
exchangers contain a group such as sulfonic or carboxylic acid. These
can react with salts to give products such as the following:
250
-------
TABLE 40. Raw Water and Anticipated Analyses
After Treatment
mg/1 as Ca 003
Substance
Cations
Sodium.
Total Cations
Anions
Bicarbonate)
Carbonate ) Alkalinity
Hydroxide )
Phosphate )
Anions
Chloride
Sulfate
ro Nitrate
£ Total Anions
Alkalinity A (Methyl Orange) . .
Alkalinity B (Phpnnlpht-hale>in)
Silica
Color
Total Solids (Cations + Si02) .
.Ca++
.Ma++
.Na++
.H+
HC03-
003—
OH-
P04
01-
S04—
N03-
as C02
as Si02
. . as Mn & Fe
1
100
100
100
0
300
150
0
0
0
75
75
0
300
200
150
0
50
0
mg/1
30
15
10
50
10
315
2
35
58
100
0
198
0
35
0
0
79
79
0
193
93
35
17
58
0
mg/1
0
A
0.2b
0.2b
10
208
3
58
7
85
0
150
0
21
0
0
64
63
0
150
65
23
14
55
0
mg/1
0
5
0.2b
0.2b
10
155
4
1
1
298
0
300
150
0
0
0
75
75
0
300
2
150
0
0
150
mg/1
30
15
0.2
0.2c
10
315
5
1
164
0
165
15
0
0
0
75
75
0
165
1
15
0
0
164
mg/1
5-10
15
0.2
0.2c
10
180
6
_
_
—
5
-
-
5
_
_
_
_
ttcr/1
5-10
15
0.2
0.2c
10
20
7
—
5
-
-
5
_
_
_
ma/1
0
0.02
0.2
0.2c
10
5
8
100
100
100
0
300
150
0
0
0
75
75
0
300
200
150
0
50
0
ma/1
30d
15
0.2c
0.2c
10
315
9
100
100
100
0
300
150
0
0
0
75
75
0
300
200
150
0
50
0
mcr/1
30d
15
0.3
0.2c
10
315
(continued on next page)
-------
TABLE 40. Raw Water and Anticipated Analyses
After Treatment (cant.)
1. Raw water
2. After cold lime softening and filtration
3. After hot process softening and filtration
4. Ion exchange softening
5. Sodium and hydrogen unit blend and degasification
6. Two-step demineralization (weak anion exchange) and degasification
7. Two-step demineralization (strong base anion resin) and degasification
8. Aeration and filtration
9. Manganese zeolite filters
a. Some reduction will occur
b. Filtered effluent
c. With proper pretreatment
d. Affected by pH adjustment
e. Iron only
Note: Ion exchange processes assume that the water was adequately pretreated.
252
-------
RSO3H + NaCl-^RSO3Na + HCl
RCO2H + Nad—9* RCO2Na + HCl
Th° above reactions are reversible and can be regenerated with acid.
Anion exchangers use a basic group such as the amino family.
RNA3OH + NaCl'-^RNASCl + NaOH
This is also a reversible reaction and can be regenerated wirh alKalies.
The combination of water treatment with both cation and anion exchangers
removes the dissolved solids and is known as demineralization (or
deionization). The guality of demineralized water is excellent. Table
Ul gives the level of total dissolved solids that is achieved. Membrane
and evaporation process water contain significantly higher solids
content and need final polishing in a demineralizer if less than 3 mg/1
dissolved solids level is reguired for the application. There are many
combinations of ion exchangers which can be used for demineralizations.
253
-------
TABLE 41. Water Quality Produced by Various
Ion Exchange Systems
Residual
Silica
Exchanger_Setug S3'!
Strong-acid No silica
cation + weak- removal
base anion
Strong-acid 0.01-0.1
cation + weak-
base anion +
stroncr-base
anion
Strong-acid 0.01-0.1
cation * weak-
base anion +
strong-acid
cation + strong-
base anion
Mixed bed 0.01-0.1
(strong-acid
cation <• strong-
base anion)
Mixed bed 0.05
+ first or second
setup above
Similar setup at 0.01
immediately above
+ continuous re-
circulation
Residual
Electro-
lytes,
253/1
0.15-1.5
0.5
0.1
0.05
Specific
Resistance
ohm-cm
3_25_C
500,000
100.000
1,000,000
1-2,000,000
3-12,000,000
18,000,000
254
-------
Four types of demineralization units will be discussed in
the cost analysis development to follow: 1. Fixed bed - strong cation -
strong anion
2. Fixed bed - strong cation - weak anion
3. Mixed bed demineralizers
4. Special ion exchange systems.
Special ion exchange systems have been developed for concentrating high
dissolved solids content (more than 1000 mg/1) total dissolved solids),
minimizing regenerant chemicals costs. Some of these special systems
are listed in Table 42.
Ion exchange is rarely used to concentrate dissolved solids in waste
streams unless some specific ion or ions need to be removed. In fact,
usually little overall is gained by this technique since regenerations
give wastes that are often as troublesome to dispose of as the original
dissolved materials. Also, the cost of even 1000 mg/1 dissolved solids
exchange is not low. Demineralization can be used for many applications
for concentrating wastes.
Chemical^Treatment
Chemical treatments for abatement of water-borne wastes are widespread.
Included in this overall category are such important subdivisions as
neutralization, pH control, precipitations and segregations, harmful and
undesirable waste modification and miscellaneous chemical reactions.
a^ Neutralization
Most of the inorganic chemicals of this study are either acidic,
alkaline or react with water to give acidic or alkaline solutions.
Others have production wastes or byproducts of acidic or basic nature.
Before disposal in surface water or other medium this acidity or
alkalinity needs to be reduced and controlled. The most common method
is to treat acidic streams with alkaline materials such as limestone,
soda ash, sodium hydroxide, and lime. Alkaline streams are treated with
acids such as sulfuric. Whenever possible, advantage is taken of the
availability of acidic waste streams to neutralize basic waste streams
and vice versa.
255
-------
TABLE 42. Special Ion Exchange Systems
System I
Application; Feedwater with high solids contents (above 1000 mg/1
TDS). There are two variations of this system — two-bed or threebed
setup. Two-bed system consists of weak-base (HCO^) anion + weak-acid
(H) cation exchangers followed by a decarbonator unit. NH40H and CO2
are used to regenerate the anion exchanger and sulfuric acid to
regenerate the cation exchanger. In place of decarbonate a second weak-
base (OH) anion exchanger is used in the three-bed Desal system.
System advantages: high flow rates; carbon dioxide recovery, good
regenerant efficiency. Limitations: solids content of water must be
less than 2000 mg/1; highly alkaline feedwater needed for best
performance; iron in feedwater cannot be tolerated.
gystem II
Application; Feedwater with high solids content.
Also employs two- or three-bed setup. Two-bed system consists of
strong-acid (H) cation + strong-base (SOjt) anion exchangers followed by
decarbonator. Sulfuric acid used to regenerate cation exchanger, raw
water the anion exchanger. In three-bed system a weak-acid (H) cation
exchanger precedes the strong-acid cation exchanger.
Advantages: raw water can be used to regenerate the strongbase anion
exchanger; high quality rinse-water not required. Limitations: ratio
of SOt* to Cl in feedwater must be high; requires high volume of rinse
water; low capacity.
System III
Application: Feedwater with high solids content.
Four-bed systems consisting of: strong-base anion (HCO3) + weak-acid
cation (H) + strong-acid cation (H) + weakbase anion (OH) exchangers.
NaHCO^ is used to regenerate anion exchangers; sulfuric acid to
regenerate cation exchangers.
256
-------
TABLE 42. Special Ion Exchange Systems (continued)
System_I.II (continued)
(continued)
Advantages: may be used on feedwater containing up to 3000 mg/1 solids,
content; high capacity and regenerant efficiency. Limitations: number
of columns required; low service flow rates; high cost of regenerants.
Condensate desalination
Mixed-bed ion exchangers have been plagued by the fact that complete
resin separation is difficult to achieve — some cation resin remains
mixed with anion resin after backwashing, with the result that sodium is
released sooner (lower capacity) ; some leakage occurs (affecting water
quality) since ammonia is usually present in condensate. This is
overcome in Ammonex process by regenerating cation exchanger with acid
and first regenerating anion exchanger with caustic and then with
ammonia to remove the sodium present in anion exchanger.
System V
Condensate desalination
Water quality and run length improved similarly as in Ammonex process
except that anion exchanger is regenerated with caustic arid lime rather
than caustic and ammonia.
em VI
Condensate desalination
Water quality and run length improved by separating mixedbed with strong
caustic solution then regenerating beds in customary procedure; i.e.,
with acid for cation exchanger and caustic for anion exchanger.
257
-------
b. BH_Control
The control of pH may be equivalent to neutralization if the pH control
point is at or close to 7. As discussed in the earlier control section,
control of excess acidity or alkalinity is best accomplished by pH meter
monitoring. The usual acceptable range for pH control is 6.0 to 9.0 for
discharge water.
c. Precipitations and Segregations
The reaction of two soluble chemicals to produce insoluble or
precipitated products is the basis for removing many undesired
waterborne (and airborne) wastes. The use of this technique varies from
lime treatments to precipitate common sulfates, fluorides and
carbonates, to sodium sulfide precipitations of mercury, copper, lead
and other harmful metals.
d. Modifications
Chemical reactions can also be used to change or destroy undesirable
wastes. Among the more common are the oxidation-reduction mechanisms.
Cyanides can be oxidized to cyanates; hexavalent chromium reduced to the
trivalent form; hypochlorites changed to chlorides; sulfites oxidized to
sulfates. These examples and many others are basic to tne modification
of inorganic chemicals waterborne wastes to make them less troublesome.
Settling Ponds and Vessels
r
The chemical treatments described in the previous section produced, in
many instances, suspended solids. These solids need to be removed but
in the moving, agitated, often turbulent waste streams flowing through
pipes, tanks, and channels, there is little opportunity to do this. In
fact, it would usually be undesirable to do so in any event — pipes and
flow channels are not easy or economical to clean.
To facilitate settling of suspended solids, large quiet settling ponds
and vessels are needed. Settling ponds are the foremost industrial
treatment for removing suspended solids.
The size and number of settling ponds differ widely depending on the
settling functions required. Waste streams with small suspended solids
loads and fast settling characteristics can be cleared up in one or two
small ponds tsurface area less than 0.1-.2 ha (1/4-1/2 ac)1. Other
ponds with heavier suspended solids loads and/or slower settling rate
may require 5 to 10 ponds and up to 405 ha (1000 ac) total surface area.
Most of the settling ponds are unlined. Costs and control
characteristics of settling ponds are the same as discussed in the
previous section on control and disposal techniques for unlined settling
ponds.
258
-------
Although not nearly as widely used as settling ponds, tanks and vessels
are also employed for reduction of suspended solids loads in inorganic
chemical production waste streams. Commercially these units are listed
as clarifiers or thickeners depending on whether they are light or heavy
duty. They also have internal baffles, compartments, sweeps and other
directing and segregating mechanisms to provide more efficient
performance. This feature plus the positive containment and control and
reduced rainfall influence (smaller area compared to ponds) should lead
to increasing use of vessels and tanks in the future.
Fi 1 tr at i on_ _£Ma jor }_
Major filtration equipment includes pressure and vacuum units of various
designs, including plate-and- frame leaf and rotary constructions.
Although it is entirely feasible for filtration equipment to be used for
removing suspended solids from waste streams, most are not filtered.
The preferred treatment for removing suspended solids is settling ponds.
Filtrations are common for collection of solid wastes from harmful
chemical treatments where complete removal is imperative. Sludges
containing metal sulfides (mercury, arsenic, etc.) are good examples of
materials handled in this way.
When the force of gravity is not sufficient to separate solids and
liquids to the desired degree, or .in the desired time, more powerful
centrifugal force can be utilized. Although there are many types of
centrifuges, most industrial units can be broken down into two major
categories -- solid bowl and perforated bowl. The solid bowl
centrifuge, as its name indicates, consists of a rapidly rotating bowl
into which the stream with suspended solids is introduced. Centrifugal
action of the spinning bowl separates the solids from the liquid phase
and the two are removed separately.
The perforated bowl centrifuge has holes in the bowl through which the
filtrate escapes by centrifugal force. The solids are retained on the
filter inside the bowl and removed either continuously (such as for the
pusher types) or in batch fashion.
Centrifuges are not widely used for inorganic chemical waste streams,
since it is rare that settling ponds or filters are not adequate for the
same suspended solids removal job.
Car bo n _ Adsorption
On the rare occasions that inorganic chemicals waste streams contain
organic materials, one of the appropriate treatments to remove these
organic components is carbon adsorption. When waste streams containing
organic contaminants are passed through activated carbon beds, the
organic material is adsorbed. When the carbon bed is saturated with
259
-------
this organic substance, the bed may be regenerated by burning off the
adsorbed organic and returning the carbon to service.
Reyerse^Osmpsis
The small pore size of the reverse osmosis membrane is both its strength
and its weakness. Its strength comes from the molecular separations
that it can achieve. Its weakness comes from the criticalness it has to
blinding, plugging, and chemical attack. Acidity, suspended solids,
precipitations, coatings, dirt, organics and other substances can make
it inoperative. Membrane life is critical and unknown in many mediums.
With these restrictions there is little wonder that its industrial
applications are few. Fortunately, the inorganic chemistry industry
water purification needs are similar to those of the areas where reverse
osmosis has been shown to be applicable — treatment of brackish water
and low (500 mg/1 to 20,000 mg/1) dissolved solids removal. Organics
are usually absent, suspended solids are low or can be made low rather
easily, acidity is easily adjusted, and most of the dissolved solids are
similar to those in brackish water — sodium chlorides, sulfates and
their calcium counterparts.
The reverse osmosis membranes used commercially are generally one to two
types — flat sheet or hollow fiber. For maximum membrane area in the
smallest space, various sheet configurations have been devised including
tubes, spiral winding, and sandwich-type structures. Sheet membranes
have been largely cellulose acetate,, while hollow fibers have been
largely polyamides. Costs for the different membrane construction are
roughly comparable. The type selected depends upon the specific
application.
Regardless of membrane type or material, the basic unit of construction
is the module (or package of membrane materials). The module is usually
integral and of the plug-in type, where a faulty module can be easily
(but not inexpensively) replaced. The modules are the heart of the
reverse osmosis process, with ancillary equipment such as pumps, tanks,
piping, pretreatment facilities and other hardware performing peripheral
functions. Module cost alone comprises one-third to one-half of the in-
stalled capital investment.
Detailed cost figures, both capital and operating, are given in Section
VIII.
260
-------
Evaporation Processes
Evaporation is the only method of general usefulness for the separation
and recovery of dissolved solids in water. others either involve mere
concentrations (reverse osmosis) or introduce contaminations for
subsequent operations (demineralizer regenerants arid chemical
precipitations) .
The evaporation process is well known and well established in the
inorganic chemical industry. Separations, product purifications,
solution concentrations are commonly accomplished by evaporative
techniques. In-depth technology for handling the common dissolved
solids in water waste streams has been developed in the soda ash, salt,
calcium chloride, and sea water chemical industries. In addition,
numerous desalination plants producing fresh water from brackish or sea
water are scattered all over the world and have been in operation for a
number of years. Seawater generally has approximately 35,000 mg/1
dissolved solids (3.5 percent by weight) while brackish water has 2,000
to 25,000 mg/1 depending on location. Some southwestern U.S. water
supplies contain dissolved solids above 2,000 mg/1 and have to be
treated similarly to brackish water.
Evaporation is a relatively expensive operation. To evaporate one kg of
water, approximately 550 kg-calories of energy is required and the
capital cost for the evaporating equipment is not low. For these
reasons industrial use of evaporation in. treating waste water has been
minimal. As the cost of pure water has increased in portions of the
United States and the world, however, it has become increasingly
attractive to follow this approach.
The treatment of water waste streams by evaporation almost always has
utilized the principle of multi-effects to reduce the amount of steam or
energy required. Thus the theoretical difficulty of carrying out the
separation of a solute from its solvent is the minimum amount of work
necessary to effect the particular change, that is the free energy
change involved. A process can be made to operate with a real energy
consumption not greatly exceeding this value. The greater the
concentration of soluble salts, the greater is the free energy change
for separation, but even for concentrated solutions the value is much
lower than the 550 kg-cal/kg value to evaporate water. Multi-effect
evaporators use the heat content of the evaporated vapor stream from
each preceding stage to efficiently (at low temperature difference)
evaporate more vapor at the succeeding stages. Thus the work available
is used in a nearly reversible manner, and low energy requirement
results. However, a large capital investment in heat transfer surface
and pumps is required. The interaction of the capital equipment costs
versus energy or operating costs will be discussed in detail in the
treatment costs section.
26]
-------
Drying Processes
After evaporative techniques have concentrated the dissolved solids to
hiqh levels, the residual water content must usually still be removed
for either recovery, sale or disposal. Water content will range from
virtually zero up to 90 percent by weight. Gas- or oil-fired dryers,
steam-heated drum dryers or other final moisture-removing equipment can
be used for this purpose. Since this drying operation is a common one
in the production of inorganic chemicals themselves, technology is well
known and developed. Costs are mainly those for fuel or steam.
Disposal Practices
Disposal of the waterborne wastes from inorganic chemicals manufacture
represents the final control exercised by the waste producer. A number
of options are available. They include discharge to surface water
river, lake, bay or ocean — and where safe and permitted, land disposal
by running effluent out on land and letting it soak in or evaporate.
Wastes may be disposed of into an industrial waste treatment plant.
Treatment and reuse of the waste stream can also be practiced. In dry
climates unlined evaporation ponds, if allowed, could be used.
Higher-cost disposal systems include lined evaporation ponds, deep well
disposal, and high-cost treatment prior to disposal or recovery. Such
methods are used for wastes which cannot be disposed of otherwise.
These wastes contain strong acids or alkalies, harmful substances, or
hiqh dissolved solids content.
Feasibility, use, and cost figures can be discussed for:
1. unlined evaporation ponds
2. lined evaporation ponds
3. deep wells
Unlined EvaporationPgnds
Two requirements must be met for an unlined evaporation pond to be
successfully utilized. First, it must be located in an area in which
unlined ponds are allowed, and secondly, the rainfall in -chat area must
not exceed the evaporation rate. This second requirement eliminates
most of the heavily industrialized area. For the low rainfall areas,
evaporation ponds are feasible with definite restrictions. Ponds must
be larqe in area for surface exposure. Evaporation of large amounts of
waste water requires larqe ponds. The availability and costs of
sufficient land place another possible restriction on this approach.
Lined Evaporation Ponds
The lined evaporation ponds now required in some sections of the country
have the same characteristics as developed for the unlined ponds
large acreage requirements and a favorable evaporation-rate-to-rainfall
balance. They are significantly higher in cost than an unlined pond.
262
-------
Such costs are developed in section VIII. Reduction of the evaporation
load is a significant advantage. For this reason, plus the short supply
and high cost of water in much of southwestern United States, dis-
tillation and membrane processes are beginning to be used in these
regions.
Deep well disposal can only be used under special conditions with a
rigorous permit system. While used for brine disposal in the petroleum
and salt industries, deep wells are usually reserved for wastes such as
strong acids, chromates, pickle liquor, and corrosive metallic salt
solutions for which no other disposal system is available.
There are several reasons for this specialization, including:
1. Costs - A
drilling ease
involved.
single well costs up to $1,500,000 depending on depth,
and criticalness, casing, exploration and monitoring
2« Geological - The geological structure in the area is of utmost
importance. In many parts of the country, deep wells are not possible.
Even in those sections where the geological structure permits their use,
deep wells must be carefully planned and coordinated using the best
geological information and expertise available.
3. Drilling __ Considerations - Deep wells are drilled by specialists
using oil well technology. While this technology is well developed,
there is always the possibility that something expensive will go wrong
— cracks, lost drills, impermeable formations, etc.
U. E§!i§tility_ - Deep wells often plug or develop operating
difficulties even after several years of good performance.
5. Extensive __ Prg treatment may be necessary to remove organics,
suspended solids and other undesirable waste components.
6. The risk of contamination of underground potable water or seismic
effects.
Most wells are approximately the same size and range in flow rate from
12.6 I/sec to 56.8 i/sec with the average being about 18.9 I/sec to 25.2
I/sec. This corresponds to approximately 1890 cu m/day capacity.
263
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SECTION VIII
COST, ENERGY AND NON-WATER QUALITY ASPECTS
COST AND REDUCTION BENEFITS OF TREATMENT
AND CONTROL TECHNOLOGIES
Summary
The inorganic chemical industry has large energy requirements for gas
furnaces, kilns, calciners, electric furnaces, reacrors, distillation
columns, and evaporators and other common equipment. In contrast,
treatment practices consume less than one tenth of one percent of this
amount. Chemical reactions and pond settling, the most commonly used
treatments, required almost no energy. Filtrations, centrifuging, and
other separation techniques are still relatively low energy processes.
The only two high energy treatments, evaporation and drying, are now
rarely used. Utilizing these treatment techniques to the extent covered
in the cost effectiveness discussions later in this section will still
maintain treatment energy at a tiny fraction of the total energy for the
industry. Total energy estimated from reference 85. Table U3
summarizes cost and energy requirements for the inorganic chemicals of
this report. To bring the processes to zero water-borne waste effluent
through total recycle of process water, rough estimates for additional
capital expenditures are 295 million dollars. Of this amount, three
industries contribute almost eighty percent. These industries — soia
ash (Solvay Process), chlor-alkali, and titanium dioxide -- have vastly
different situations from the other chemicals.
Titanium dioxide has no satisfactory replacement. It can absorb and
pass on the large capital and operating costs needed for waterborne
waste cleanup. This major clean-up is also long overdue. Development
and application of existing treatment technology can save the titanium
dioxide industry an estimated 100 million dollars over the full
neutralization costs given in Table 43.
The chlor-alkali industry differs from both soda ash (Solvay) and
titanium dioxide in that mainly in-process changes and more efficient
use of raw materials are required to attain zero water-borne waste.
There are many ways to accomplish this, some of which are suggested in
Sections VII and VIII of this report.
Solar evaporation sodium chloride production presents a problem in that
the magnesium-rich bitterns have to be stored. Before storage space and
costs become a major problem, use of these natural resources should be
encouraged.
Other industries that have major capital expenditures in Table U3,
sulfuric acid, nitric acid, sodium metal (which is similar in process
265
-------
TABLE 43. Summary of Cost and Energy Information for Attainment of Zero Discharge
Additional Energy
CTi
Chemical
Aluminum Chloride
Aluminum Sulfate
Calcium Carbide
Hydrochloric Acid
Hydrofluoric Acid
Lime
Nitric Acid
Patassium Metal
Potassium Chromates
Sodium Bicarbonate
Potassium Sulfate
Sodium Chloride (Solar)
Sodium Silicate
Sulfuric Acid
Hydrogen Peroxide
(Organic)
Sodium Metal
Sodium Sulfite
Calcium Chloride
Sodium Chloride
Chlor-Alkali
Hydorgen Peroxide
(Electrolytic)
Additional
Capital, $
4,
1,
11,
1,
20,
4,
3,
1,
7,
40,
0
700,
0
250,
180,
0
000,
0
90,
0
570,
0
850,
000,
350,
700,
730,
040,
750,
000,
15,
000
000
000
000
000
000
000
000
000
000
000
000
000
000
000
IO6
Btu/yr
0
17,000
0
0
3300
0
0
0
210
0
680,000
0
332,000
0
0
0
116,000
0
0
800,000
870
io6
Kg cal/yr
0
4300
0
0
8350
0
0
0
53
0
162,000
0
84,000
0
0
0
29,300
0
0
202,000
220
Incremental
Cost
Percent of June,
List List
$/ton $/metric ton Price
0
0.90
0
0.05
13-16
0
0.22
0
4.65
0
1.60
2.20
0.90
0.10
1.00
2.25
2.50
0.20
1.00
0.50
(combined
0.25-.75
1
0
0
.0
0
.06
14-18
0
5
1
2
1
0
1
2
2
0
1
0
0
.24
0
.15
0
.16
.42
.0
.11
.10
.48
.75
.22
.10
.45
1
0
.4
0
$/ton
>255
62.80
171.40
1973
Price
$/metric ton
280
69
188
0.04 110(100%)121
2
0
0
3
0
0
0
2
0
»v
.5
0
.18
0
.97
0
.7
11
.95
.33
.2
.6
.1
.5
5
0.5
product basis)
0.27-.83
0.1
560(100%)617
19.50-
21.75
113 (100%) 124
__
480
88
42.50
~20
95
28-32
460
(70%Sol'n) _
375
117
42
•w20
Cl2$75
NaOH $110
(75%)
460
(70%Sol'n)
21.50-
24
528
97
47.50
-*22
102
30.75-35
505
,
412
129
46
.— 22
$83
$121
507
(continued on next page)
-------
TABLE 43. Summary of Cost and Energy Information For Attainment of Zero Discharge (continued)
Additional
Capital, $
4,100,000
0
25,000,000
74,000,000
96,000,000
294,895,000
Addjtional
To6
Btu/yr
240,000
0
200,000
675,000
535,000
3,590,000
Energy
KT
kg cal/yr
60,700
0
50,200
170,000
135,000
905,000
Incremental
Cost
$/ton
16
0
1.60
64
96
— —
$/metric ton
18
0
1.76
70
103
_ —
Percent of
List
Price
4.6
0
4.5
11.4
17.1
•«
June
List
, 1973
Price
$/ton $/metric ton
345
24-33
35.50
550-570
550-570
«••
380
26-36
39
605-61 5
605-615
w«
Chemical
Sodium Dichromate
Sodium Sulfate
Soda Ash
Titanium Dioxide
(Chloride)
Titanium Dioxide
(Sulfate)
Totals
''Chemical Marketing Reporter, June 4, 1973.
sd on 3 million tons/year vacuum pan salt production from Salt, Bureau of Mines Minerals Yearbook, 1969.
'Based on $2.00/ton chlor-alkali production — estimated from cost effectiveness data of subsections VIII,
1.5.3.1 and 1.5.3.2.
****Based on full neutralization plus demineralization costs as given in subsections VIII, 1.5.5.1 and 1 .5.5.2.
*****Based on deep-welling costs as in subsection VIM 1 .5.4.1 .
*
**
***
-------
wastes to chlor-alkali plants), aluminum sulfate, sodium dichromate, and
sodium chloride (brine or mining) have these costs primarily because of
the large size of the industry or harmful wastes. Except for sodium
chloride (brine or mining) and sodium dichrcmate all waste abatement
costs for these chemicals are below 1.5 percent of the list price.
For all chemicals except soda ash, titanium dioxide, sodium dichromate,
and sodium chloride (solar), the yearly cost for total water-borne waste
abatement is less than U percent of the current list price.
Energy reguirements of 905 X 109 kg cal/yr (3.6 X 1012 BTU/yr) or the
energy equivalent to burning 10.220 cubic meters (3.6 million gallons)
of fuel oil for the elimination of water-borne wastes for the chemicals
of this study are less than that currently consumed by one large Solvay
soda ash plant.
Thermal pollution was not encountered in this study nor was noise or
other types of pollutions.
In general, plant size itself does not appear to be a significant factor
influencing waste effluents on a kkg waste/ kkg of product basis.
Multichemical complexes have an advantage over single isolated
facilities on costs and options for waste utilization. Plant age does
have some influence, with the new plants, naturally, being favored.
These are by no means the controlling criteria, however. For example,
nineteen exemplary plants used in the cost effectiveness development
given later in this section have an average age of 21 years, with 5
plants of 30 years or greater age and 6 of 10 years or less age.
Geographical location is often a critical factor for waste disposal
costs. Availability of deep welling, ocean barging, or solar
evaporation options is an advantage. Also, the western United States
has more incentive to recover and reuse ocean water than the east.
New plants being built can avoid major future waste abatement costs by
inclusion of: (1) Dikes, emergency holding ponds, catch basins, and
other containment facilities for leaks, spills and washdowns. (2)
Piping, trenches, sewer, sumps and other isolation facilities to keep
leaks, spills and process water separate from cooling and sanitary
water. (3) Non-contact condensers for cooling water. Barometric con-
densers should be avoided. (4) A fuul water treatment system, including
demineralization, reverse osmosis, evaporative and solids waste handling
equipment when needed. (5) Efficient reuse, recycling and recovery of
all possible raw materials and by-products regardless of inherent value.
Sodium chloride and sodium sulfate are two by-products which frequently
cause trouble. (6) Closed cycle water utilization whenever possible.
Closed cycle operation eliminates all water-borne wastes. Generally, if
water is pure enough for discharge, it is pure enough for reuse.
268
-------
Cost References and Rationale
Cost information contianed in this report was obtained directly from
industry during exemplary plant visits, from engineering firms and
equipment suppliers, and from the literature. The information obtained
from these latter three sources has been used to develop general
capital, operating and overall costs for each treatment and control
method. Costs have been put on a consistent industrial calculation
basis of ten year straight line depreciation plus allowance for interest
at six percent per year (pollution abatement tax-free money) and
inclusion of allowance for insurance and taxes for an overall fixed cost
amortization of fifteen percent per year. This generalized cost data
plus the specific information obtained from plant visits was then used
for the cost effectiveness estimates in this section and whenever else
costs are mentioned in this report.
Cost developments, calculations, references and rationales for treatment
and disposal techniques pertinent to the inorganic chemicals industry
are detailed in Supplement A. A summary of these costs is given in
subsection l.U. In addition to the costs developed in Supplement A,
costs for specific plant treatment systems are given in Supplement B.
The combination of these two costs sources and engineering judgment
extrapolations from them are used in subsection 1.5 for cost
effectiveness development.
Definition of Levels of Control and Treatment
For each chemical of this study, there is technology available for
reduction to zero effluent or closed loop status. Using the general
models as given in Figures 74 and 75, cost and energy effectiveness
values are developed. Four levels of treatment and control are
considered:
Level A -- Base level practices followed by most of the industry and
exceeded by exemplary plants.
Level B — Treatment and control practices at the average exemplary
plant.
Level C -- Based upon the best technically and economically feasible
treatment and control technology.
Level D — Complete water-borne waste elimination. This level may or
may not be economically feasible for the specific chemical.
Cost Effectiveness Information by Category
The general cost information developed in subsection 2.0 is now applied
to specific categories and chemicals of this study. In the following
water effluent treatment cost sheets, the costs for each of the four
levels of waste abatement described in subsection 1.3 are developed.
269
-------
ANCILLARY
OPERATIONS
(COOLING
TOWER,
BOILERS)
N>
-J
O
WATER
TREATMENT
AREA
SOLID MAKEUP
WASTES WATER
EMERGENCY
POND
OR
TANK
PROCESS
EFFLUENTL
CHEMICAL
TREATMENT
EMERGENCY
TREATMENT
FACILITIES
TOXIC
CHEMICAL
REMOVAL
SOLID
WASTES^
SOLID
WASTES
I
SOLID
WASTES
y
SUSPENDED
SOLIDS
REMOVAL
PURE
WATER
DISCHARGE
FIGURE 74
MODEL FOR WATER TREATMENT AND CONTROL SYSTEM
INORGANIC CHEMICALS INDUSTRY
-------
FILTRATION
HIGH
DISSOLVED
SOLIDS
STREAMS
SUSPENDED
SOLIDS
REMOVAL
pH ADJUST
OTHER
CONDITIONING
MAKEUP WATER
'HIGH
SOLIDS
STREAM
REVERSE
OSMOSIS
UNITS
LOW
DISSOLVED
SOLIDS
STREAMS
SUSPENDED
SOLIDS
REMOVAL
pH ADJUST
OTHER
CONDITIONING
V
INCINERATION,
FINAL
EVAPORATION
SOLID
WASTE
TO REUSE,
SALE OR
LANDFILL
LOW
ENERGY
EVAPORATION
REGENERANTS
FOR
POLISHING
SOFTENERS
ION EXCHANGERS
DEMINERIZERS
yy-
-> PURE WATER BOILERS,
WATER TOWERS AND
-> OTHER REQUIREMENTS
PROCESS WATER
•OF
DESIRED PURITY
FIGURE 75
MODEL FOR WATER TREATMENT SYSTEM
INORGANIC CHEMICALS INDUSTRY
-------
Category 1
Aluminum Chloride
There are no water-borne process wastes. The only ancillary waste would
result from air pollution control. Two exemplary plants of this study
have no wastes from this source. As discussed subsequently, air
pollution abatement contributions to water effluents are costed as zero
cost and energy. All such costs are credited to air pollution costs.
Exemplary plant number 125 has been chosen for cost effectiveness devel-
opment (see Table 44). This is a 30 year-old plant of nominal 22.5
kkg/day (25 ton/day) capacity. Treatment facilities are newly
installed.
Energy requirements are very low (small pumps and stirrers) and are
taken as 0.75 kwh (1 horsepower-hr.). Converting this to common units
gives 5,300,000 kg cal (21,000,000 Btu) or 79.5 1/yr (21 gal/yr) of fuel
oil energy equivalent.
For the entire industry, the energy requirement would be 17,100,000 kg
cal (68,000,000 Btu) or 257 1/yr (68 gal/yr) of fuel oil energy.
Treatment costs for air pollution control are $1.88/kkg ($1.70/ton) of
product. Treatment costs and energy requirements for water pollution
control are zero.
Aluminum Sulfate
>
Two exemplary closed-cycle plants, numbers 049 and 063, were visited
during this study. Exemplary plant 063 is chosen for cost effectiveness
analysis. This 46-year-old plant has an average production of 36
kkg/day (40 tons/day). Cost effectiveness information is given in Table
45.
Energy requirements for pumps, clarifiers, drives, etc., are taken as
7.5 kwhr (10 hphr) or 53 x 10kg cal (210 x lOBtu) or 795 liters/yr (210
gal/yr) of fuel oil energy.
Entire industry energy for treatment is estimated as 4300 x 10 kg cal
(17,000 x 10 Btu) or 64,000 liters (17,000 gallons) of fuel oil per
year.
Treatment costs for closed cycle zero effluent are $1.87/metric ton
($1.70/ton) of which $1.00/kkg ($0.90/ton) of product represents
additional cost above typical operation in all plants.
Calcium Carbide
The calcium carbide process, per se, has no water-borne waste. The only
possible contributions are scrubbers to remove dusts and particulates
272
-------
TABLE 44
Water Effluent Treatment Costs
Inorganic Chemicals
Chemical: Aluminum Chloride (22.5 kkg/day (25 tons/day) Capacity)
Treatment of Control Technolo-
gies Identified under Item
III of the Scope of Work:
Investment
Annual Costs:
Interest + Taxes and
Insurance
Depreciation
Operating and Maintenance
Costs (excluding energy
and power costs)
Energy and Power Costs
Total Annual Cost
Effluent Quality:
Effluent Constituents
Parameters (Units) Raw
(kg/kkg (tbs/ton) Waste
Load
AI..~:~. ,™ f~ui~.-:,j^ -»- 7^n ^n\*
A B C D
0 100,000 100,000 100,000
0 5,000 5,000 5,000
0 10,000 10,000 10,000
0 0** 0** 0**
0 ~0 ~0 ~0
0 15,000*** 15,000*** 15,000***
Resulting Effluent
Levels
7
-------
TAPT.K 45.
Water Effluent Treatment Costs
Inorganic Chemicals
Chemical: Aluminum Sulfate (36 kkg/day (40 tons/day) Capacity)
Treatment of Control Technolo-
gies Identified under Item
III of the Scope of Work:
Investment
Annual Costs:
Interest + Taxes and
Insurance
Depreciation .
Operating and Maintenance
Costs (excluding energy
and power costs)
Energy and Power Costs
Total Annual Cost
A
40,000
2,000
*
4,000
5,000
—
11,000
B C D
100,000
5,000
10,000
8,000
1,000
24,000
Effluent Quality:
Effluent Constituents t
Parameters (Units) Paw
kg/kkg (Ibs/ton) Waste Resulting Effluent
Load Levels
Silicon Dioxide 20 (40) 1(2) 0
Titanium Dioxide 20 (40) 1 (2) 0
Aluminum Oxide 10(20) 1(2) 0
Aluminum Sulfate 0.25 (0.5) 0.05 (0.1) 0
A — Typical treatment taken as pond settling — total pond area of 0.4 hectare (one
acre) (unlined).
B — Best average treatment level involves clarifiers plus additional ponds + level A
ponds and closed cycle operation.
274
-------
from the gas streams. Costs for cleaning up air pollution abatement
contributions to water effluents are credited to air pollution costs.
therefore, energy and costs for water-waste abatenu-nt tor calcium
carbide are zero.
For information purposes, a cost-effectiveness sheet. Table 46, has been
prepared for air pollution abatement costs for exemplary plan- I'-fO of
this study. In this case air pollution control costs are zero since
recovered raw materials pay for total annual costs. Hydrochloric Acid
(Chlorine-Purning)
During normal operation the chlorine-burning hydrochloric acid process
has no water-borne wastes. Startup wastes are less than one pound per
ton and are typically neutralized in sodium hydroxide solutions. Cost
effectiveness information is given in Table 47 using exemplary plant 121
as a model. Addition of a small sodium hypochlorite destruction ve?-f;^l
Dins a pump and transfer line to chlor-alkali brine for reuse gives zero
effluent from the process. Total cost for zero effluent attainment is
.BO. 33/kkq ($0.30/ton) of product, while the incremental cost for qoing
from typical +-0 zero effluent treatment levels is $O.G55/kkg
($0.05/ton). Energy costs are negligible.
Hydrofluoric Acid
Hydrofluoric acid, lik^ the other mineral acids, has a very low water-
borre waste load. Good engineering, maintenance and housekeeping bring
thc waste effluent down to 0 .'5 kg/kkg (one Ib/ton) or less. A complete
recycle zero discharge plant, number 152, of 27 kkg/day (30 ton/day)
capacity and 15 years age, is chosen for cost effectiveness calculation
as given in Table 48, column 4 (alternate B).
The large cost differential between Level C and alternate B shows that
two different approaches make a substantial difference in the costs
irvolved. Plant Oil follows stoichiometric use of sulfuric acid,
thereby eliminating $30,000 neutralization chemical costs per year.
They handle calcium sulfate and calcium fluoride dry by hauling to land
dump, thereby eliminating pond settling and dredging costs for another
$70,000/yr differential. In-process changes account, tnerefore, for
•57.70/kkg ($7/ton) difference in treatment costs.
Total cost for zero water waste effluent achievement for plant Oil is
•517.60/kkg ($16/ton) and for plant 152 is $14.30/kkg ($13/ton) . By far
the greatest portion of this cost is for handling and disposal of solid
calcium sulfate, which has to be done in all plants.
Additional energy reguired for going from base level treatment to closed
cycle operation is negligible. An additional 7.5 kw (10 horsepower) is
allowed for pumping from collection ponds back to the system. This
gives 53,000,000 kg cal (210,000,000 Btu) or 795/1 (210 gal) of fuel oil
275
-------
TABLE 46.
Water Effluent Treatment Costs
Inorganic Chemicals
Chemical: Calcium Carbide (127 kkg/day (140 tons/day) Capacity)
Treatment of Control Technolo-
gies Identified under Item
III of the Scope of Work:
Investment
Annual Costs:
Interest + Taxes and
Insurance
Depreciation
Operating and Maintenance
Costs (excluding energy
and power costs)
Energy and Power Costs
A B C D
0 Not known
Not known
Not known
0 Not known
0 Not known
Total Annual Cost
Effluent Quality:
Effluent Constituents
Parameters (Units)
K9/1
-------
TABLE 47.
Water Effluent Treatment Costs
Inorganic Chemicals
Chemical: Hydrochloric Acid (36 kkg/day (40 tons/day) Capacity)
Treatment of Control Technolo-
gies Identified under Item
III of the Scope of Work:
Investment
Annual Costs:
Interest + Taxes and
Insurance
Depreciation
Operating and Maintenance
Costs (excluding energy
and power costs)
Energy and Power Costs
Total Annual Cost
A
10,000
500
1,000
2,000
~0
3,500
B* C
10,000 15,000
500 750
1,000 1,500
2,000 2,000
-o ~o
3,500 4,250
D
15,000
750
1,500
2,000
~0
4,250
Effluent Quality:
Effluent Constituents
Parameters (Units) Raw
(PoundsAon) Waste
Load
Resulting Effluent
Levels
Chlorine & Hydrogen
Chloride
0.5(1) 0.75(1.5) 0.75(1.5)*
0
Levels A and B — Neutralization in sodium hydroxide solution followed by discharge to
surface water.
Levels C and D— Destruction of sodium hypochlorite in small pond or vessel and use of
sodium chloride solution in chlor-alkali system. Chlorine-burning
hypochloric acid units are always located in chlor-alkali complexes.
""This corresponds to exemplary plant operation with wastes only during startup. Level I
guideline recommendation modelled to C.
277
-------
TABLE 48.
Water Effluent Treatment Costs
Inorganic Chemicals
Chemical: Hydrofluoric Acid (36 kkg/day (40 tons/day) Capacity)
Treatment of Control Technolo-
gies Identified under Item
III of the Scope of Work: A
Investment
Annual Costs:
Interest + Taxes and
Insurance
Depreciation
Operating and Maintenance
Costs (excluding energy
and power costs)
Energy and Power Costs
Total Annual Cost
>
Effluent Quality:
Effluent Constituents
Parameters (Units) Raw
kgAl<9 (Pounds/Ton) Waste
Load
0
0
B*
30,000
1,500
Alternate
C B**
50,000 75,000
0 3,000
50,000 52,000
50,000 56,500
2,500 3,750
5,000 7,500
60,000 165,000
1,000 5,000
68,500 181,250
Resulting Effluent
Levels
3650(7300)
110(220)
62.5(125)
2.5(5)
12.5(25)
1 2.5(25)
0
0
0.5(1)
2.5(5)
12.5(25)
12.5(25)
0
0
0.25(0.5)
0.25(0.5)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Calcium Sulfate
Sulfuric Acid
Calcium Fluoride
Hydrogen Fluoride
Hydrofluorosilicic Acid
Silicon Dioxide
Level A — Land dumping of calcium sulfate, minimizing acid by operating near stoichio-
metry requirements. Costs are all for trucking of calcium sulfate, calcium fluoride
and contained sulfuric acid to land dump.
Level B — Similar to Exemplary Plant 011 of this study.
Level C — Closed loop extension of Ql 1.
''Exemplary plant operation, Level I guideline recommendation based on modelling to
Level C, or equivalent to alternate Level B.
''Exemplary closed loop plant 152 (27 kkg/day).
278
-------
energy per year. Total industry additional energy requirement3 are
830,000,000 kg cal (3300,000,000 Btu) or 12,490/1 (3300 gal) of fuel
oil.
Calcium Oxide and Calcium Hydroxide (Lime)
There is no water-borne waste from the process. Therefore, no cost or
energy is involved.
For informational purposes cost effectiveness Table 49 is given for
eliminating air pollution. Cost is $1.45/kkg ($1.32/ton) for dry bag
collec-t-ion installations. If, as discussed later in this section, water
scrubbing plus elimination of water-borne wastes is more economical than
$1.45/kkg ($1.32/ton) of calcium oxide produced, then water scrubbing
should be used.
Nitric Acid
There is no water-borne waste from the nitric acid process, nor is there
usually any contribution from air pollution treatment equipment. Only
leaks, spills, monitoring and containment costs are involved.
For 7-year-old 281 kkg/day (310 ton/day) exemplary plant 114 there are
no effluents except boiler and cooling tower blowdowns. These are over
378,500 liters/day (100,000 GPD) in volume and illustrate comments made
later in this section regarding ancillary streams. Ancillary streams
are disregarded as far as ' guideline specifications are concerned,
however, so exemplary plant 114 has zero guidelines defined effluent.
Since no cost figures are available for nitric acid, they are taken as
the same as for sulfuric acid isolation and containment costs of
$160,000. Applying this cost to the 288 kkg/ day (320 ton/day) plant
gives $0.24/kkg ($0.22/ton) cost for isolation and containment of leaks
and spills. No energy addition is involved.
Potassium (Metal)
There are no process, air pollution or ancillary water wastes involved
for this chemical.
Potassium Chromates
Since potassium dichromate is made from the reaction of sodium
dichromate with potassium chloride, there is none of the massive ore
waste present as in the sodium dichromate process. The only water-borne
wastes from the exemplary 25-year-old 13.5 kkg/day (15 ton/day) plant
002 of this study are from once-through cooling water used on the
barometric condensers. Replacement of these condensers with non-contact
heat exchangers, as planned for 1974, will make this a zero water-borne
279
-------
TABLE 49.
Water Effluent Treatment Costs
Inorganic Chemicals
Chemical: Lime - Air Pollution Costs Only (281 kkg/day (310 tons/day) Capacity)
Treatment of Control Technolo-
gies Identified under Item
III of the Scope of Work:
Investment
Annual Costs:
Interest + Taxes and
Insurance
Depreciation
Operating and Maintenance
Costs (excluding energy
and power costs)
Energy and Power Costs
Total Annual Cost
>
Effluent Quality:
Effluent Constituents
Parameters (Units) Raw
(Pounds/Ton) Waste
Load
A
0
0
0
0
0
BCD
675,000 675,000 675,000
33,750 33,750 33,750
67,500 67,500 67,500
35,000 35,000 35,000
2,500 2,500 2,500
138,750 138,750 138,750
Resulting Effluent
Levels
Kiln Dusts
67(134) 67(134)
~0
~0
~0
Level B — Dry bag collectors installed.
280
-------
waste plant. Cost for this conversion is estimated at $60,000. See
Table 50.
The treatment differential in going from base Level A to zero discharge
costs $5.12/kkg ($U.65/ton) of potassium dichromate. Here is a case
where initial installation of a non-contact condenser would have saved
$60,000 and reduced treatment costs to $3.25/kkg ($2.95 per ton).
Energy requirements for pumps, filters, centrifuges, and other equipment
is taken as 7.5 kilowatts (10 horsepower) overall, or 53,000,000 kq
cal/yr or (210,000,000 Btu/yr). Entire industry additional energy is
estimated at the same value.
Potassium Sulfate
•The treatment and control cost effectiveness values for potassium
sulfate using exemplary plant 118 as a model are developed in Table 51.
Costs for going from base treatment level to zero effluent is $2.38/kkg
($2.16/ton) of potassium sulfate.
There is a relatively high energy recovery process with 67,000,000,000
kg cal (265,000,000,000 Btu) or 1,000,000/1 (265,000 gal) of fuel oil
energy per year. For the entire industry the additional energy
requirement is 172,000,000,000 kg cal (680,000,000,000 Btu).
Sodium Bicarbonate
>
Water-borne wastes from sodium bicarbonate facilities are small. Using
exemplary plant 166 as a model, cost effectiveness values are developed
in Table 52.
Reducing the bicarbonate wastes to zero should be virtually cost free
since current product losses should cover expenses.
There are no siqnificant new energy requirements.
Sodium Chloride (Solar)
It has been recommended that concentrated magnesium-rich residual brines
or bitterns from solar salt manufacture be stored and eventually used
for their chemical value. Solar energy of great magnitude has been used
to concentrate these brines and it would be wasteful of both the
country's energy as well as raw materials not to utilize them.
Taking exemplary plant 059 as a model, cost effectiveness values are
developed in Table 53.
One 146 hectare (360 acre) pond is needed each year. While this storage
capacity is available for the next 5 to 10 years, obviously it cannot go
281
-------
TABLE 50.
Water Effluent Treatment Costs
Inorganic Chemicals
Chemical: Potassium Chromare (13.5 kkg/day (15 tons/day) capacity)
Treatment of Control Technolo-
gies Identified under Item
III of the Scope of Work:
Investment
Annual Costs:
Interest + Taxes and
Insurance
Depreciation
Operating and Maintenance
Costs (excluding energy
and power costs)
Energy and Power Costs
Total Annual Cost
>
Effluent Quality:
Effluent Constituents
Parameters (Units) Raw
(PoundsAon) Waste
Load
A B*
20,000 50,000
C D
110,000 110,000
1,000
2,500
2,000 5,000
0 10,000
5,500
11,000
10,000
0
1,000
3,000 18,500
Resulting Effluent
Levels
Sodium Chloride 400(800) 400(800) 0 0
Filter Aid 0.85(1.7) ~0.05(~0.1) 0 0
Potassium Dichromate ,~0.5(~1) ~0.5(~1) ~0.5(~1) ~0
Level A — Discharge of all water to settling pond to remove filter aid.
5,500
11,000
10,000
1,000 1,000
27,500 27,500
0
0
-0
Level B — Centrifuge, filter, pumps, piping and installation for sodium chloride and filter
aid removal. Salt value has been assumed zero.
Level C — Non-contact heat exchangers installed.
*Exemplary plant, Level I guidelines recommendations modelled to Level C, plans for
1974 for exemplary plant.
282
-------
rr->^r" 51
.l^'j." v._ir.» *J i •
Water Effluent Treat-rent Costs
Inorganic Cheinicals
G-.errJ.cal: Potassium Sulfate (454 kkg (500 tons) per day Capacity)
Treatzrent or Control Technolo-
gies Identified under Item
III of the Scope of Work: A B C D
Investment 40,000 700,000 700,000 700,000
Annual Cos ts:
Interest + Taxes and 2,000 35,000 35,000 35,000
Insurance
Depreciation -' 4,000 70,000 70,000 70,000
QperatingandMainteneir.ee 10,000 124,000 124,000 124,000
Costs (excluding energy
and pcwer costs)
Energy and Pcwer Costs ~0 166,000 166,000 166,000
Total Annual Cost 16,000 395,000 395,000 395,000
Effluent Quality:
Effluent Constituents
Parairaters (Units) Raw
3 (Pounds/Ion) Waste Resulting Effluent
Load Levels
Ore Muds 15(30) 00 00
Waste Liquor 2000(4000) 2000(4000) 000
Level A — Pond settling of muds. Discharge of dissolved solids to surface water.
Level B — Evaporation to recover liquor chemicals and water + Level A value of recovered
chemicals not deducted from costs. Water value is also not deducted.
283
-------
T?J3LE 52.
Water Effluent Treatirent Costs
Irorgonic Chemicals
Chemical: Sodium Bicarbonate (272 kkg/day (300 ton/day) Capacify)
Treatirent of Control Technolo-
gies Identified under Item
III of the Scope of Work:
Investment
Annual Costs:
Interest + Taxes and
Insurance
Depreciation
Operating and Maintenance
Costs (excluding energy
and power costs)
Energy and Power Costs
Total Annual Cost
Effluent Quality:
Effluent Constituents
Parairsters (Units) Eaw
kgAkg (PoundsAon) Waste
Load
A B C D
10,000 15,000 15,000 15,000
500
750
750
1,000 1,500
1,000 2,000
Sodium Carbonate
Sodium Bicarbonate
Rubbish
30(76)
10(20)
<2.5(<5)
750
1,500 1,500
2,000 2,000
~0
2,500
38(76)
10(20)
0
~0
4,250
Resulting
Leva
38(76)
0
0
~0
4,250
Effluent
Is
0
0
0
0
4,250
0
0
0
Level A — Settling pond, landfill for rubbish, discharge to surface water.
Level B -- Redissolve broken bags and waste sodium bicarbonate + Level A.
Level C ~ Recycle sodium carbonate to Solvay Process system. Value obtained equal cost.
^Exemplary plant plans to go to Level C in near future, hence Level I guidelines recommenda-
tions were modelled to Level C.
284
-------
'.QBI.E 53.
Water Effluent Treatrent Costs
Irorgo-o.ic Chemicals
Cher-ical: Solar Salt (2540 kkg/day (28COtons/day) Capacity)
Treatment of Control Technolo-
gies Identified under Item
III of -the Scope of. Work: .A B C D
Investment 14,400,000 14,400,000 14,400,000 14,400,000
Annual Costs:
Interest + Taxes and 720,000 720,000 720,000 720,000
Insurance
Depreciation -' 1,440,000 1,440,000 1,440,000 1,440,000
Operating and Maintenance ~0 ~0 ~0 ~0
Costs (excluding energy
and power costs)
Energy and Power Costs ~0 ~0 ~0 ~0
Total Annual Cost 2,160,000 2,160,000 2,160,000 2,160,000
Effluent Quality:
Effluent Constituents
Pararrsters (Units) Esv
(Pounds/Ton) VTasta Result!. \g Effluent
Load Levels
Bitterns 70,000(140,000) 000
Level A — 1 new 360 acre unlined pond per year is needed. Costs are taken from
Section VIII for unlined ponds.
285
-------
on indefinitely. Use of these valuable mineral deposits should be made
in the near future.
Storage costs for solar salt bitterns for exemplary plant 050 are
$2.42/kkq (?2.20/ton).
Additional energy requirements are negligible.
Sodium Silicate
The wastes from the sodium silicate process are relatively small and
closed loop zero effluent operation has been achieved in exemplary plant
072.
For the purpose of cost effectiveness, development plant 134 has teen
selected for Table 54 calculations. This plant is a ten-year-old, 72
kkq/day (80 ton/day) facility. Costs are approximately $1.00/kkq
($0.90/ton) of product.
Additional energy costs using this approach are 3,530,000,000 kg cal
(14,000,000,000 Etu). For the total industry, additional energy
requirements are 84,000,000,000 kg cal (332,000,000,000 Btu).
A second aoproach using only Level A treatment and closing the loop for
zero effluent bypasses both the energy requirements and most of the
cost. This approach is used in our exemplary plant 072. Treatment
costs for this approach woul^ be approximately $0.22/k.kg ($0.20/ton) of
product.
Costs for both approaches are reasonable. In view of the energy
advantage for plant 072's approach, this recycle method should be
favored.
Sulfuric Acid
The sulfuric acid (sulfur-burning) process has no process wastes. The
only water-borne wastes are from leaks, spills, air pollution control
equipment, and ancillary operations such as cooling tower blowdowns and
ion-exchange regenerants. Since cooling tower and ion-exchange
regenerants are not considered waste for -the guidelines, they are not
included here. Air pollution conmational purposes since they are costed
in this study as zero effluent at zero cost.
Regen plants for making sulfuric acid from waste or spent acid are not
specifically covered in this study but are included in cost
effectiveness development for informational purposes.
Exemplary sulfur-burning plant 141, a three-year-old 360 kkg/day (400
ton/day) plant, was used as the model.
286
-------
TABLE 54.
Wabar Effluent Treatment Costs
Inorganic Chemicals
Chemical: Sodium Silicate (72 kkg/day (80 tons/day) Capacity)
Treatment of Ccntrol Technolo-
gies Identified under Item
III of the Scope of ttbrk:
Investment
Annual Costs:
Interest + Taxes and
Insurance
Depreciation
Operating and Maintenance
Costs (excluding energy
and power costs)
Energy and Power Costs
Total Annual Cost
Effluent Quality:
Effluent Constituents
Pararrabers (Units) Raw
(Pounds/T°n) Vlasta
Load
.A B* C* D
26,000 42,000 62,000 62,000
1,300
2,600
1,000
2,106
4,200
9,000
3,100
4,900 15,300
Resulting Effluent
Levels
3,100
6,200 6,200
10,000 10,000
10,000 10,000
29,300 29,300
2(4)
2.5(5)
2(4)
0.5(1)
0.5(1)
2(4)
2.5(5)
0
0
0.5(1)
2(4)
2.5(5)
0
0
0
0
0
0
0
0
0
0
0
0
0
Sodium Silicate
Sodium Sulfate
Filter Aids
Sand
Sodium Hydroxide
Level A — Settling pond only.
Level B — Settling pond plus neutralization (existing good plant).
Level C — Evaporation to remove and recover dissolved solids + Levels A and B treatment,
Sodium silicate recovered (exemplary plant).
*Note Level C is exemplary plant level in this table.
287
-------
Costs are less than $0.10 per kkg ($0.10/ton) of product. Additional
energy is negligible. See Table 55.
Regen plant 023 is given similar development in Table 56 using a 675
kkg/day (750 ton/day) fourteen-year-old facility with extensive
pollution control expenditure. Regen plants have to get rid of a stream
of weak sulfuric acid, after which they behave much as a sulfur-burning
facility.
The differential costs in this case from Level A treatment to
essentially zero waste discharge status of Level D is approximately
$2.UO/kkg ($2.20/ton) of sulfuric acid produced for overall air plus
water pollution abatement, and $0.55/kkg ($0.50/ton) or sulfuric acid
produced, for water pollution abatement alone.
Additional energy requirements for water pollution abatement are
negligible. Air pollution contributions for the abatement equipment
used are relatively high for sodium sulfate recovery 25,200 kg cal
(100,000,000,000 Htu) or 378,500/1 (100,000 gal) of fuel oil energy.
Regen plant 023, having spent almost four million dollars for water and
air pollution control is a model for regen sulfuric acid waste abatement
practices and is recommended for technology and costs for specific
problem solutions.
Category 2
Hydrogen Peroxide (Organic)
The organic process effluent contains waste hydrogen peroxide plus
organic solvent used in the process. The nature of this solvent is
regarded as a trade secret.
Cost effectiveness information is developed in fable 57 for exemplary
plant 069, a twenty-year-old 85 kkg/day (94 ton/day) facility.
Estimated additional cost to attain zero waste discharge level is
approximately $1.10/kkg ($1.00/ton) of hydrogen peroxide produced.
Additional energy requirement should be negligible.
There are a number of alternative procedures which could be implemented,
starting with isolation and containment of waste streams from cooling
water, to reduce waste discharge to essentially zero at feasible cost
levels.
Sodium Metal
Sodium metal is produced as coproduct with chlorine in the Downs Cell
process. Since the chlorine produced is handled similarly and has the
288
-------
TABLE 55.
Water Effluent Treatrrsnt Costs
Irorgonic Ch&?icals
Chenical: Sulfuric Acid (Sulfur Burning)(360 kkg/day (400 tons/day) Capacity)
Treatrrent of Control Technolo-
gies Identified under Item
III of the Scope of Work:
Inve3ta!ent
Annual Costs:
Interest -f Taxes and
Insurance
Depreciation "':
Operating and Maintenance
Costs (excluding energy
and power costs)
Energy and Power Costs
Total Annual Cost
Effluent Quality:
Effluent Constituents
Pararreters (Units) Raw
kg/kkg(PoundsAon) V7aste
. A B
50,000 100,000
c: D
160,000 160,000
2,500
5,000
~0
5,000
10,000
~0
8,000
16,000
7,500 15,000
Resulting Effluent
Levels
Spills, Leaks
0
8,000
16,000
~0
24,000 24,000
1(2) 0.5(1) 0
Closed Cycle System
Level A — Typical diking and containment.
Level B — Good isolation and containment + Level A.
Level C — Lined containment emergency pond — 0.4 hectare (1 acre) + Level A and B.
289
-------
56.
Water Effluent Treatment Costs
Inorganic Chemicals
Chemical: Sulfuric Acid (Regen Plant) (675 kkg/day (750 tons/day) Capacity)
Treatrrent of Control Technolo-
gies Identified under Item
III of the Scope of VTbrk: .A B C D
Investment 100,000 1,250,000 3,750,000 3,750,000
Annual Costs:
Interest + Taxes and 5,000 62,500 187,500 187,500
Insurance
Depreciation " 10,000 125,000 375,000 375,000
Operating and Maintenance 50,000 10,000 15,000 15,000
Costs (excluding energy
and power costs)
Energy and Power Costs ~0 ~0 ~0 76,000
Total Annual Cost 65,000 197,500 577,500 $£3,500
Effluent Quality:
Effluent Constituents
PararrBters (Units) Raw
kg/kkg (PcwndsAon) Waste ' Resulting Effluent
Load Levels
Spills & Leaks 1(2) 0.5(1) ~0 ~0 ~0
Weak Sulfuric Acid 82.5(165) 00 00
Sodium Sulfate - - - 23.5(47) 0
Level A — Typical diking and containment plus neutralization of weak acid + 1 acre settling
pond.
Level B — Level A + improved diking, isolation and containment, lined emergency pond, all
indirect cooling, surge basins, rainfall decanter, final disposition of weak acid,
recycle of strong acid streams.
Level C — Full air pollution system added.
Level D — Removal of air pollution wastes at no cost. In this case raw material value recovered
equals cost.
290
-------
1P.BI.E 57.
Water Stfluent Treatrrsnt Costs
Inorganic Gieroicals
Cha-Tical: Hydrogen Peroxide (Organic Process) (85 kkg/day (94 tons/day) Capacity)
A
23,000 53,000
C
200,000
1,150
2,300
3,000
~0
2,650
5,300
3,000
~0
6,450 10,950
D
0
10,000 10,000
20,000 20,000
5,000 5,000
Treatment of Control Technolo-
gies Identified under Item
III of the Scope of V7ork:
Investment
Annual Costs:
Interest 4- Taxes and
Insurance
Depreciation
Operating and Maintenance
Costs (excluding energy
and power costs)
Energy and Power Costs
Total Annual Cost
Effluent Quality:
Effluent Constituents
Parameters (Units)
kg/kkg (Po\>fids/Ton)
Organics
Hydrogen Peroxide
Level A — Reduction of hydrogen peroxide with scrap iron, organics removal by mechanical
separation.
Level B — Level A + improved organics removal and spill containment.
Level C — Closed loop process water, non-contact cooling water only effluent.
35,000 35,000
Raw
Load
0.25(0.5)
20(40)
Resulting Effluent
Levels
0.1(0.2)
5(10)
0.025(0.05)
5(10)
0
0
0
0
:Not exemplary plant, modeled.
291
-------
same wastes as the mercury and diaphragm cell processes to be discussed
later only wastes specific to the Downs cell and sodium production are
included here. Table 58 gives the estimated cost effectiveness values
for a 58 kkg/day (65 ton/day) fourteen-year-old plant (096) .
Costs for plant 096 for essentially zero water-borne waste effluent are
$2.47/kkg ($2.25/ton) of sodium above initial expenditures of $3.30 to
$4.40/kkg ($3 to 34/ton) of sodium, which is currently selling for $412/
kkg ($375/ton).
Additional energy costs should be negligible.
Sodium Sulfite
The wastes from the sodium sulfite processes are essentially sodium
sulfite. Table 59 gives the cost effectiveness values for exemplary
plant 168, a fifteen-year-old installation.
Costs for reducing exemplary plant 168 to essentially zero water-borne
waste status are approximately $2.75/kkg ($2.50/ton) of product. If
recovery of sodium sulfite is directed at the same stream as now
converted to sodium sulfate and directly discharged, there is a
potential for $25,000 pr/yr profit. Plants not now treating or
recovering sodium sulfite should explore this approach.
Additional energy reguired is approximately 1,620,000,000 kg gal/yr
(6,400,000,000 Btu/yr or 24,200/1 (6400 gal) of fuel oil energy/yr. For
the entire industry this would be 29,200,000,000 kg cal (116,000,000,000
Btu) or 439,000/1 (116,000 gal) -of fuel oil energy per year.
Calcium Chloride
Calcium chloride comes from two major sources, Solvay soda ash by-
product and brine chemicals by-product. A forty-five-year old 450
kkg/day (500 ton/day) brine reclamation plant 185 is used for cost
effectiveness development, as shown in Table 60. Solvay process plant
wastes are obscured by the overall process discharges.
Cost for elimination of present wastes is roughly estimated as $0.22/kkg
($0.20/ton) of product.
No additional energy requirements are involved.
Sodium Chloride (Brine Mining)
Unlike the solar salt industry where all wastes are stored or disposed
of in surface ponds, the other salt producers get their salt from
underground and return most wastes to underground disposal.
292
-------
TSBLF. 58.
Water Effluent Treatrrent Costs
Inorganic Chemicals
Chemical: Sodium Metal (58 kkg/day (6$tons/day) Capacity)
Treatrrent of Control Technolo-
gies Identified under Item
III of the Scope of ttbrk:
Investment
Annual Costs:
Interest + Taxes and
Insurance
Depreciation
Operating and Maintenance
Costs (excluding energy
and power costs)
Energy and Power Costs
Total Annual Cost
Effluent Quality:
Effluent Constituents
Pararrs'bers (Units) Raw
(Pou.ids/Ton) Wa3ts
Load
BCD
400,000 700,000 0
0 20,000
0 40,000
4,000 4,000
35,000 35,000
70,000 70,000
10,000 10,000
'"""'v/ " /"t"*U
4,000 64,000 115,000 115,000
Resulting Effluent
Levels
57.5(115) 57.5(115) 57.5(115) ~0
30(60) 30(60) 30(60) ~0
000
Sodium Chloride
Misc. Alkaline Salts
Bricks, Anodes, Other
Solids
Level A — Disposal of salts plus solids.
Level B — Facilities for separating salts from solids.
Level C — Containment, isolation and return of salts to brine system.
~0
~0
293
-------
TABLE 59. "
Water Effluent Treatment Costs
Inorganic Chstdcals
Giemical: Sodium Sulfite (45 kkg/day (50 ton/day) Capacity)
Treabnsnt of Control Technolo-
gies Identif isd undar Item
III of the Scope of Work:
Investment
Annual Costs:
Interest + Taxes and
Insurance
Depreciation
Operating and Maintenance
Costs (excluding energy
and power costs)
Energy and Power Costs
Total Annual Cost
Effluent Quality:
Effluent Constituents
Paraireters (Units) Raw
k&/fckg (Povi-ids/Ton) Waste
Load
Sodium Sulfate
Sodium Sulfite 30.5(61)
-
. . A
0
0
0
0
0
0
B
250,000
12,500
25,000
10,000
2,000
49,500
C
275,000
13,750
27,500
1 2,000
7,000
47,750
D
150,000
7,500
15,000
5,000
6,000
/25,000) Pro fit
Resulting Effluent
Levels
_
30.5(61)
29(58)
1 .5(3)
0
0
0
0
Level A ~ No treatment — typical for industry.
Level B — Full treatment system, but dissolved solids still discharged.
Level C — Level B + evaporation recovery and sales of recovered product. Product value
$12,500. .
Level D — Isolation and containment parts of complete system of Level B + evaporation to
recover sodium sulfite. Product value is $58,500.
294
-------
TABLE 60.
Water Effluent Treatment Costs
Inorganic Chericals
Chemical: Calcium Chloride (450 kkg/day (500 tons/day) Capacity)
Treat-rent of Control Technolo
gies Identified under It-em
III of the Scope of TMbrk:
Investment
Annual Costs:
Inters:-; • -;• Taxes and
Depreciation
Operating and Maintenance
Costs (excluding energy
and power costs)
Energy and Power Costs
Total Annual Cost
Effluent Quality:
Effluent Constituents
Parartaters (Units) Raw
kg/kkg (PoundsAon) Waste
Load
Calcium Chloride
Sodium Chloride
Ammonia
30(60)
0.5(1)
0.5(1)
A* B C D
0 200,000 200,000 200,000
0
10,000
10,000 10,OOC
0
0
0
0
30(60)
0.5(1)
0.5(1)
20,000
0
0
30,000
Resulting Ef
Levels
0.5(1)
0
0
20,000
0
0
30,000
fluent
~o
~o
-0
20,000
0
0
30,000
~o
~o
Level A — Normally these wastes, as dissolved solids are discharged to surface water in
non-exemplary of soda ash plants.
Level B — Replacement of barometric condensers with non-contact heat exchangers.
Level C — Elimination of packing station water-waste contributions.
*Level A corresponds to present performance of "exemplary" plant in this table. Level B
modelled to near future plans of this plant.
295
-------
Exemplary plant 030, a forty-nine-year old 1,000 kkg/day (1,100 -con/day)
facility is used for cost effectiveness developments in Table 61.
Complete elimination of salt wastes in plant effluent surface water
would cost for a new plant, approximately $0.28/kkg ($0.25/ton) of pro-
duct. This assumes plant 030 technology plus initial installation of
non-contact final condensers and conveying and packing losses being
recovered dry and either reused or land (or well) disposed.
Elimination of all but 1 kg/day (2 Ihs/ton) waste from plant 030 would
cost approximately $0.55/kkg ($0.50/ton). of product.
Negligible additional energy would be required.
Soda Ash (Solvay Process)
The Solvay process produces approximately 1370 kg (3000 Ibs) dissolved
solid wastes for every kkg (ten) of product. These solids consist of
slightly over 0.91 kkg (one ton) of calcium chloride, which has high
solubility, is difficult to obtain in anhydrous form and spontaneously
picks up moisture from the air when land dumped, and about 0.45 kkq
(one-half ton) of unreacted sodium chloride, also of high solubility.
Although there is a market for calcium chloride, the total volume of
this market can be supplied with 10 to 15 percent of the calcium
chloride available from Solvay plants alone. Therefore, most of the
available calcium chloride must be disposed of at zero value or less
(disposal costs). The sodium chloride can be reused if it can be
separated from the calcium chloride and other wastes, but the value of
this raw material is so low that it is uneconomical to recover it.
Therefore, half a dozen Solvay Plants discharge more waste to surface
water than any other chemicals industry and there is no general
economically feasible way for them to avoid it. Costs are given below
for Solvay process plant 166. This 2520 kkg/day (2800 ton/day), ov~r
seventy-five-year-old facility, is used for cost developments.
Treatment_and Control Method Capital Costs $ Annual Cost $
1. Coproduction of ammonium 34,000,000 26,000,000
chloride with soda ash
2. Ammonia and hydrogen chloride 133,000,000 45,000,000
from ammonium chloride
3. Ammonia and chlorine from 80,000,000 34,000,000
ammonium chloride
4. Deep well disposal 6,000,000 1,600,000
5. Total evaporation plus ocean 51,000,000 31,000,000
barging of solid wastes
Options 1, 2, and 3 are process changes or additions with monstrous
capital investments. The quantities of ammonium chloride, hydrogen
chloride and chlorine produced either exceed present total market or
296
-------
TABLE 61 .
Witter Efcluent Treatment Costs
Inorganic Chemicals
Chemical: Sodium Chloride (Brine/Mining) (1000 kkg/day (1100 ton/day) Capacity
BCD
500,000 1,000,000 600,000
50,000 30,000
100,000 60,000
10,000 10,000
Treatrrent of Control Technolo-
gies Identified" under Item
III of the Scope of Work:
Investment
Annual Costs:
Interest + Taxes and
Insurance
Depreciation
Operating and Maintenance
Costs (excluding energy
and power costs)
Energy and Power Costs
Total Annual Cost
Effluent Quality:
Effluent Constituents
Parana ters (Units)
kg/kkg (Pounds/Ton)
Sodium Chlorine
Brine Sludge
Level A — No information.
Level B — Plant 030 technology, sludge returned to wells. Control system developed including
$425,000 damming, curbing, collection and pumping to wells, and $63,000 instru-
mentation and miscellaneous pumps and piping.
Level C — Level B + non-contact heat exchangers for barometric condensers.
Level D — For new plants. Elimination of conveying and packing station losses peculiar
to Plant 030.
25,000
50,000
10,000
~0
85,000
160,000 100,000
PvHW
Waste
Load
50(100)
2.5(5)
Resulting Effluent
levels
6(1 2)
0
1(2)
0
~o
~o
297
-------
would be such major contributors that the market structure would be-
drastically altered. The other two options are disposal methods.
The only economically feasible disposal options for Solvay process soda
ash wastes today are: (1) partial recovery of calcium chloride for sales
and (2) deep welling. Since the Solvay soda ash wastes are similar to
those for brine salts and oil well salts, which are extensively deep-
welled, a qood case can be made for such disposal, if geologically
feasible at the plant location (or close by).
Cost effectiveness values are developed using these two tecnnologies in
Table 62.
Additional costs for zero discharge of wastes to surface water are
approximately $0.55/kkq ($0.50/ton) of product. For deep-welling
disposal alone, costs for zero waste effluent are $1.76/kkq
($1.60/ton) produced. Additional energy requirements, primarily for
calcium chloride recovery, are high. Estimated requirements for plant
166 are 315,000 x 106 kg cal/yr (1,250,000 x 106 Etu/yr) or for the
entire industry 1,260,000 x 106 kg cal/yr (5,000,000 x 10* Btu/yr).
Without calcium chloride recovery, about 12,500 x 106 kg cal/yr (50,000
x 106 Btu/yr) for plant 166 or 50,000 x 10* kg cal/yr (200,000 x 1O6
Btu/yr) for the industry, would be needed for deep welling.
Category 3
Mercury-Cell, Chlor-Alkali
Both chlorine and sodium hydroxide are produced by the mercury cell
process. Potassium hydroxide is produced similarly by starting with
potassium chloride brine instead of the usual sodium chloride.
Cost effectiveness values are developed in Table 63 using two year-old
158 kkg/day (175 ton/day) (chlorine basis) plant 098.
For zero water-borne wastes the cost above Levels A and B mercury
removal is approximately $1.00/kkg($0.90/ton) of chlorine produced.
Spreading these costs to chlorine and sodium hydroxide co-products
reduces the value to approximately $0.55/kkg ($0.50/ton) of products.
Roughly 2,520 x 10* kg cal/yr (10,000 x 106 Btu/yr) additional energy is
required for this plant.
Plants have now reduced water effluent mercury discharges to
approximately O.OU5-0.225 kg/day (0.1-0.5 Ib/day) by spending Level A
and B money. Some exemplary plants have spent Level C money (plant 098
is at this level). Level D money, in many cases, may not be needed.
The particular plant modelled happens to have a negative water balance
from rainfall into open tanks and vessels.
298
-------
E 62.
Water Effluent Treatirent Costs
Inorganic Chemical
Chemical: Soda Ash (2520 kkg/day (2800 tons/day) Capacity)
A
D
500,000 21,500,000 27,500,000 27,500,000
25,000 1,075,000 1,375,000 1,375,000
2,750,000 2,750,000
3,675,000 3,675,000
1,000,000 1,000,000
520,000 520,000
Treatirent of Control Technolo-
gies Identified under Item
III of the Scope of Work:
Investeant
Annual Costs:
Interest + Taxes and
Insurance
Depreciation
Operating and Maintenance
Costs (excluding energy
and paver costs)
Energy and Power Costs
Total Annual Cost
Effluent Quality:
Effluent Constituent
Pararretars (Units)
kg/kkg (Pounds/Ton)
Calcium Chloride
Sodium Chloride
Calcium Carbonate
Calcium Oxide
Calcium Sulfate
Ash and cinders
Silicon Dioxide
Level A — Settling ponds
Level B — Level A + evaporation of 20% of stream to recover calcium chloride for sale at
$44Akg ($40/ton) — 8,280,000 value.
Level C — Level B + deep well disposal.
50,000 2,150,000
375,000 3,175,000
800,000
450,000 (1,080,000)
Profit
Raw
Waste
Load
1100(2200)
500(1000)
85(170)
1 35(270)
31 (62)
40(80)
58^(117)
1100(2200)
500(1000)
~o
25(50)
2.5(5)
~o
~o
Resulting E
Levels
900(1 800)
500(1000)
~o
25(50)
2.5(5)
~o
~o
ffluent
0*
0*
0*
0*
0*
0*
0*
0*
0*
0*
0*
0*
0*
0*
* No surface water effluent.
299
-------
TABun 63.
Water Effluent Treatirsnt Costs
Inorganic Chemicals
Giemical: Mercury Cell Chlor-Alkali (158 kkg/day (175 tons/day) Capacity)
Treatment of Control Technolo-
gies Identified under Item
III of tha Scope of Work:
Inves tenant
Annual Costs:
Interest + Taxes and
Insurance
Depreciation
Operating and Maintenance
Costs (excluding energy
and power costs)
Energy and Power Costs
Total .Annual Cost
Effluent Quality:
Effluent Constituents
Params ters (Units) Raw
kg/kkg (PoundsAon) Waste
Load
A B C D
500,000 500,000 700,000 750,000
25,000
50,000
55,000
1,000
25,000 35,000
50,000 70,000
55,000 61,000
1,000
2,000
Resulting Ef f luant
Levels
Sodium Chloride
Sodium Hypochlorite
Mercury
50(100) 50(100) 50(100)
20(40) 20(40) 20(40)
<0.05(<0.1) <1 xlO~.T <7xlO'5
(<2xlO
37,500
75,000
64,000
7,000
131,000 131,000 168,000 183,500
70(140) ~0
~0 ~0
. <7xlO"5 ~0
~3) (<1.4xlO"4)(<1.4xlO"4)
o
Level A — Reduction of mercury to less than 1 x 10"J
Level B — Reduction of mercury to less than 7 x 10~^ kg/kkg.
Level C — Level B + catalytic conversion of sodium hypo chlorite to sodium chloride.
Plant 098 is at this level.
Level D — Level C + evaporation and reuse of sodium chloride. No effluent except cooling
water from system. Drying sulfuric acid to other use or concentration.
300
-------
Diaphragm Cell, Chlor-Alkali
Diaphragm cells also produce both chlorine and sodium hydroxide (or
potassium hydroxide if potassium chloride brine is used).
Table 64 gives the progressive cost effectiveness development for one-
y°ar-old 2070 kkg/day (2300 ton/day) 057. Costs for essentially zero
water-borne effluent are approximately $0.55/kka ($0.50/ton) of product.
For new facilities the cost would be considerably less, since non-
contact condensers should be used in place of barometric condensers.
Additional energy requirements are negligible.
Hy.iroqen Peroxide (Electrolytic)
Electrolytic process hydrogen peroxide is produced in twentyyear-oid
Qxemplary plant 100. Table 65 gives cost effectiveness information.
Reduction of this plant to zero discharge of process waste would per
ton) of product produced.
Additional energy required would be 220 x 106 kg cal (870 x 1C6 3tu) .
Sodium Bichromate The sodium dichromate process has heavy suspended and
dissolved solids levels primarily because of the chromium treatment pro-
ccss used. Two-year-old 149 kkg/day (164 ton/day) exemplary plant 184
is used as the model for cost effectiveness development as shewn in
Table 66.
Additional cost above typical treatment Level A is $17.60/ Kkg (i>16 o-r
ton) of product, of which $13.207 ($12/ton) is already being spent in
exemplary plant 184. Evaporation to recover dissolved salts costs
$4.40/kka ($4/ton) of product. Selling price of sodium dichrornat^ is
$380/kk.g ($345/ton).
These fiaures illustrate the expensiveness of isolating, containing,
treating and disposing of harmful wastes as discussed in Sections VII
and VIII. They also show that if the effluent streams can be kept
small, 1,317 cu m/day (348,000 GPD) in this case, removal of dissolved
salts by evaporation is expensive but not prohibitively so.
It is believed that, while the isolation, containment and treatment
facilities of exemplary plant 184 are exceptional, there are more
economical ways of achieving the same level of chromium in the effluent.
Additional energy requirements are estimated to be 25,200 x 106 kg cal
(100,000 x 106 Btu) per year for plant 184. For the industry, using
similar treatment (which is doubtful) to zero waterborne waste
301
-------
TABLE 64.
Water Effluent Treatment Costs
Inorganic Chemicals
Chemical: Diaphragm Cell, Chlor-Alkali (1810 kkg/day (2000 ton/day) Capacity)
Treatment of Control Technolo-
gies Identified under Item
III of the Scope of Work:
Investeent
Annual Costs:
Interest + Taxes and
Insurance
Depreciation
Operating and Maintenance
Costs (excluding energy
and power costs)
Energy and Power Costs
Total Annual Cost
A
45,000
2,250
4,500
24,000
30,750
B
65,000
3,250
6,500
224,000
1,000
234,750
c
495,000*
3,250
6,500
224,000
1,000
234,750
D
1,500,000
75,000
150,000
224,000
1,000
450,000
Effluent Quality:
Effluent Constituents
Parameters (Units)
kgAkg (Pounds/Ton)
Calcium Carbonate sludge
Sodium Hypochlorite
Spent Sulfuric Acid
Chlorinated Hydrocarbons
Sodium Chloride
Sodium Hydroxide
Eaw
VJaste
Load
12.25(24.5)
7.5(15)
4(8)
0.7(1.4)
25.5(51)
22(44)
Eesulting Effluent
Levels
0
7.5(15)
4(8)
0.7(1.4)
25.5(51)
22(44)
0
7.5(15)
0
0
5(10)
4.5(9)
0
0
0
0
500)
4.5(9)
0
0
0
0
0
0
Level A — Settling Pond.
Level B ~ Chlorinated hydrocarbons to disposal pit + sulfuric acid to sales, neutralization of
sodium hydroxide and brine returned to system.
Level C — Installation of chlorine burning hydrochloric acid plant for chlorine tail gas.
Hydrochloric acid value equal to cost.
Level D — Non-contact cooling substituted for barometric condensers - rough estimate.
*Cost of installation ~ 0 contribution to cost — see Level C note.
302
-------
TABLE 65.
Water Effluent Treatrrent Costs
Inorganic Chemicals
Chemical: Hydrogen Peroxide - Electrolytic (12 kkg/day (13.2 ton/day) Capacity)
Treatrrent of Control Technolo-
gies Identified under Item
III of the Scope of Work:
A
Investment
Annual Costs.:
Interest
Insurance
B . C
12,500 15,000
Taxes and
Eepreciation
Operating and Maintenance
Costs (excluding energy
and power costs)
Energy and Power Costs
Total Annual Cost
Effluent Quality:
Effluent Constituents
Parameters (Units) Raw
kg/kkg. (Pounds/Ton) Waste
Load
625
1,250
1,600
3,475
750
1,500
2,000
1,000
5,250
Resulting Effluent
Levels
Sodium Sulfate
Ammonium Sulfate
0.75(1.5) 0.75(1.5) 0.75(1.5)
0.75(1.5) 0.75(1.5) 0.75(1.5)
-0
-0
Level A — There is no typical plant.
Level B — Present plant operation
Level C — Distillation to dryness 1136 liters/day (300 GPD)
D
303
-------
TABLE 66.
Water EfFluent Treatment Costs
Inorganic ChaiU-cals
Chemical: Sodium Dichromate (149 kkg/day (164 tons/day) Capacity)
Treatxrent of Control Technolo-
gies Identified under Item
III of the Scope of Work: A B C D
Investment 100,000 1,000,000 1,800,000 1,800,000
Annual Costs:
Interest + Taxes and 5,000 5,000 90,000 90,000
Insurance
Depreciation -' 10,000 100,000 180,000 180,000
Operating and Maintenance _Q 560,000 610,000 610,000
Costs (excluding energy
and power costs)
Energy and Paver Costs ~0 4,000 64,000 64,000
Total Annual Cost 15,000 669,000 944,000 944,000
Effluent Quality:
Effluent Constituents
Paramefcers (Units) Raw
kg/kkg (Pounds/Ton) Waste Resulting Effluent
Load levels
Total Suspended Solids 900(1800)0.125(0.25)0.125(0.25) ~0 ~0
Total Dissolved Solids 88.5(177) 88.5(177) 88.5(177) ~0 ~0
Chromium 6 - - 0.0001(0.0002) ~0 ~0
Level A — Settling pond.
Level B — Segregation and chemical treatment for chromium-6. Pond settling and discharge
of clear effluent to surface water.
Level C — Level B + evaporation to recover dissolved sodium chloride. Recovered sodium
chloride costed as zero value. Closed loop operation.
304
-------
discharge, the additional energy requirements would be 60,500 x 106 kg
cal (2UO,000 x 106 ptu) .
Sodium Sulfate
So3ium sulfate is a by-product of sodium dichromate and other processes.
As such, it has no water-borne wastes of its own. Therefore, it is a
zero effluent-zero treatment and control chemical with zero additional
energy requirements.
Titanium Dioxide (Chloride Process)
Most chloride processes for titanium dioxide production use either
rutil-- or "synthetic rutile" ore. DuPont is able in its process to use
lower-grade ores bu^ for the purposes of this cost effectiveness
discussion, the DuPont process is considered to be on-site beneficiation
plus a "synthetic rutile" process.
Currently chloride process wastes are treated or disposed of bv compiet-c-
neutralization, deep-wellina and ocean barging. For companies already
oceaning bargring cost run $5.50 - $11 kkg ($5 to $10 per ron) of
titanium dioxide product. For those starting barging a location further
from the ocean, or requiring extensive shore facilities, tne costs may
range from $11 to $22/kkg ($10 to $20/ton).
Deep-welling costs run from $2.20 to $5.50/kkg ($2 to $5/ton) of
titanium dioxide product. Complete neutralization, on the other hand,
is much more expensive. Table 67 shows the cost ~f f ectiven-^ss
development for this approach using ten-year-old 67 kkg/day (74 tor/day)
exemnlary plant 009 as the model.
Complete neutralization which is now don° by plant 009 costs i>40/kkg
($36/ton) differential over base treatment Level A..
deduction to virtually zero discharge of wastes costs $71 per kkq
($64/ton) of product. Titanium dioxide sells for $605 to S627/kkg ($550
to $570/ton) .
Additional energy costs are roughly estimated to be 13,000 x 106 kg cal
(50,000 x 106 Etu) for plant 009 and 170,000 x 10* kg cal (675,000 x 10*
Btu) for the entire industry using the same treatment.
The chlorine process, disregarding ocean barging and deep-welling
disposals, for current technology has more waste than the sulfate
process. The lower grade ore process is particularly bad, arid may be
considered an on-site beneficiation with all the waste attendant.
Both Government and Industry should strive to improve on current
technology following the paths of:
305
-------
TABLE 67.
Water Ecfluent Treatirsnt Costs
Inorganic Chemicals
G-iemical: Titanium Dioxide (Chloride Process),67 kkg (74 ton) per day basis
Treatrrent of. Control Technolo-
gies Identified under Item
III of tha Scope of Work:
Investment
Annual Costs:
Interest + Taxes and
Insurance
Depreciation
Operating and Maintenance
Costs (excluding energy
and power costs)
Energy and Power Costs
Total .Annual Cost
Effluent Quality;
Effluent Constituents
Paraireters (Units)
(PoundsAon)
Iron Hydroxides
Other metal oxides
Ore
Titanium hydroxides
Hydrochloric Acid
Titanium Dioxide
Coke
Soluble Chlorides and
su I fates
.A B C D
300,000 4,000,000 5,300,000 5,300,000
15,000 200,000 265,000 265,000
30,000 400,000 530,000 530,000
10,000 390,000 890,000 890,000
10,000 45,000
45,000
55,000 1,000,000 1,730,000 1,730,000
Raw
Load
65(130)
65(130)
1 38(276)
25(50)
227(454)
40.5(81)
23(46)
Resulting Effluent
Levels
65(1 30)
65(1 30)
29(58)
227(454)
~0
~o
~0
~o
~o
~o
~o
315(630)
~o
~o
~o
~0
~o
~o
~0
-o
~o
~o
~o
~o
Leval A -
Level B -
Level C -
Level D -
— Pond settling.
- Complete chemical treatment facility + land dumping of solid waste.
— Level B + specialty unit demineralization + evaporation of regenerant solution.
— Same as Level C.
306
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1. Feneficiation of ore at mine site or other remote locations to reduce
waste loads in current plants which are often not located in areas
compatible with large mining-type disposal. There are various processes
some in commercial status, others ir. research or development stages.
Research and development should be encouraged.
?. Improved utilization of present ore and process wastes. Ferric
chlorid^-, one of the major wastes, has been researched and is being
researched by various people — the steel industry particularly.
Valuable metals such as vanadium are also being wasted.
If -»-h~ above programs are followed, then chloride process wastes will be
reduced significantly. in the absence of an alternative plan, the total
neutralization approach is feasible, available, and reliable.
Titanium Dioxide (Sulfate Process)
Th.n sulfate process for producing titanium dioxide has the heaviest
water-borne waste load p»r ton of product of all the processes of this
s^udy. Of th~ approximately three/kkg waste/kkg of product, two Kkg are
sulfuric acid. There is no present exemplary plant. Plant 122 of this
s^udy has publicly announced, however, plans for complete cleanup of
wastes and it is essentially this model which will be followed in cost
effectiveness development. The model plant used, however, is non-
exemplary plant 142, a twenty-sevenyear old 108/kkg/day (120 ton/day)
facility. Cost effectiveness is developed in Table 68.
Additional costs in ooing from typical Level A to virtually complete
elimination of water-borne wastes are $106/kkg ($96/ton) or 10.52/kg
(4. 82/ll«) of titanium dioxide produced. Going to Level C costs $90/kkg
($82/ton) or 9.0«Vkq (4.10/lb).
This is compared to $8.80 to $11.0/kkg ($8 to $10 /ton) for ocean
barging of strong acid wastes. Adding Level B costs of approximately
$ll/kko ($10/ton) to this gives about $22/kkg ($20/ton) for removal of
acidity and the largest portion of the wastes. Ocean barging, as men-
tioned for the chloride process, can range for new plants (or old plants
not now using this disposal means) up to $33/kkg ($40/ton) or 4>44/kkq
($40/ton) overall waste costs. Thus, ocean barging costs about one-
fourth to one-half that of complete neutralization.
Acid recovery is another attractive approach. Using a current EPA-
support pilot plant as model for acid recovery, cost effectiveness is
developed in Table 69. Additional costs for this approach are i53/kkg
($48/ton) of titanium dioxide produced for practically zero water-borne
waste eliminating Level D. Without demineralization, additional costs
above Level A are $37.50/kkg ($34/ton) or about onehalf that for
complete neutralization.
307
-------
TABLE 68.
Water Effluent Treatment Costs
Inorganic Chemicals
Chemical: Titanium Dioxide (Sulfate Process), 108 kkg (1 20 ton) per day basis
Treatment of Control Technolo-
gies Identified under Item
III of the Scope of Work:
Investoient
Annual Costs:
Interest + Taxes and
Insurance
Depreciation
Operating and Maintenance
Costs (excluding energy
and power costs)
Energy and Power Costs
Total Annual Cost
. A
100,000
5,000
10,000
65,000
~0
80,000
B
150,000
7,500
15,000
400,000
~o
422,500
C
10,000,000
500,000
1,000,000
2,000,000
10,000
3,510,000
D
11,500,000
575,000
1,150,000
2,350,000
45,000
4,120,000
Effluent Quality:
Effluent Constituents
Parameters (Units) Raw
kgAkg (PoundsAon) Waste Resulting Effluent
Load Levels
SulfuricAcid 2025(4050) 2025(4050) 17*5(3490) _0 ~0
Iron Sulfate 387(774) 387(774) 370(740) ~0 ~0
Aluminum Sulfate 270(540) 270(540) 260(520) ~0 ~0
Magnesium Sulfate 220(440) 220(440) 210(420) ~0 ~0
Other metal suflates 35(70) 35(70) 35(70) ~0 ~0
Sol id Wastes 210(420) 20(40) 20(40) ~0 ~0
Soluble Calcium Sulfate - 265(530) ~0
Level A — Settling Pond
Level B — Level A + neutralization of weak acid stream.
Level C — Full neutralization.
Level D — Level C + specialty system demineralization + evaporation of regenerant solution.
308
-------
TABLE 69.
Water Eff luant Treatrrsnt Costs (Acid Recovery Option)
Inorganic Chemicals
ChaniLcal: Titanium Dioxide (Sulfate Process)«l 08kkg (1 20/ton) per day basis
Trsatirent of Control Technolo-
gies Identified under Item
III of the Scope of Work:
Investeent
Annual Costs:
Interest + Taxes and
Insurance
Depreciation
Operating and Maintenance
Costs (excluding energy
and power costs)
. A
100,000
5,000
1,000
65,000
B
150,000
7,500
15,000
400,000
C
4,000,000
200,000
400,000
500,000
D
5,500,000
275,000
550,000
850,000
Energy and Power Costs ~0 ~0 400,000 445,000
Total .Annual Cost 11,000 422,500 1,500,000 2,120,000
Effluent Quality:
Effluant Constituents
Pararrsters (Units) Raw
(PoundsAon) Waste Resulting Effluent
Load Levals
SulfuricAcid 2025(4050) 2025(4050) 1745(3490) ~0
Iron Sulfate 387(774) 387(774) 370(740) ~0 ~0
Aluminum Sulfate 270(540) 270(540) 260(520) ~0 ~0
Magnesium Sulfate 220(440) 220(440) 210(420) ~0 ~0
Titanium Sulfate 180(360) 180(360) 130(260) ~0 ~0
Other metal sulfates 35(70) 35(70) 35(70) ~0 ~0
Solid Wastes 210(420) 20(40) 20(40) ^0 ~0
Soluble Calcium Sulfate - ~ 200(-400) ~0
Level A -- Settling Ponds
Level B — Level A + weak acid stream neutralization.
Level C — Level B + acid recovery facilities.
Level D — Level C + specialty system demineralization + evaporation of regenerant solution,
309
-------
Required additional energy for complete neutralization plus
demineralization and evaporation of regenerant is 41,500 x 106 kg cal/yr
(Ur000 x 106 Btu/yr) for plant 142 and 135,000 x 10* kg cal/yr (535,000
X 106 Btu/yr) for the industry (sulfate process).
Similar values for acid recovery are 160,000 x 106 kg cal (630,000 x 10*
Btu) for plant 142 and 1,320,000 x 10* kg cal (5,200,000 x 10* Btu) .
Summarizing the costs for rough comparison purposes gives:
Cost/kkg (Cost/Ton)
Dile^hol Titanium Dioxide
Ocean barging and weak acid $22 ($20)
neutralization
Acid recovery $44 ($40)
Total neutralization $88 ($80)
Overlaps in costs can occur depending on specific circumstances. Since
most of the neutralization products are insoluble calcium sulfate and
metallic oxides and hydroxides, the complete neutralization of sulfate
process wastes is a relatively "clean" process. Also, its simple tested
technology reliability is attractive. Acid recovery is still in the
development stage for the process described. Corrosion problems are the
biggest current uncertainty. The cost of this approach is one-half that
of complete neutralization, however, and there is no reason why
technology know-how can not be brought to bear on this process.
GENERAL INFORMATION ON COST OF CONTROL AND TREATMENT SYSTEMS
Segregation of contaminated water streams from non-contaminated streams
is the first and most important step in water-borne waste abatement.
Since the treatment costs normally depend on the volume of water to be
treated more than the amount of waste, keeping the wastewater volume
small reduces costs and energy requirements. Spills, leaks and
washdowns are small, but need to be contained and isolated.
Cost for segregation and containment vary over a wide range depending on
the size and complexity of the plant, volume and nature of the wastes,
and the equipment employed.
Rough estimates of these costs based on information obtained from
exemplary plant visits are given in Table 70. In general, small
chemical plants produce 50 tons per day or less of product. However,
this may vary significantly with the particular chemical.
Isolation for toxic wastes containing mercury ,and chromium usually costs
approximately $200,000 to $300,000. Large salt, acid and chlor-alkali
plants also fall in a similar price range for isolation and containment
310
-------
costs. Older plants may be more difficult and expensive to modify than
the cost of similar features in new facilities.
TABLE 70. Isolation and Containment Costs
Purpose Installations Small_Plants Large Plants
Isolation Trenches and sewers $ 10,000- $100,000-
pipelines, sumps, 100,000 300,000
catch basins, tanks
and pumps
Containment Dikes and curbing $ 5,000- $ 50,000-
50,000 200,000
Isolation Non-contact heat- $ 50,000 $100,000-
exchangers 500,000
Barometric condensers are the most common source o£ cooling water
contamination. They change cooling water to process water and increase
both cost and energy treatment requirements. No new plant should be
built with barometric condensers unless they do not contribute to waste
loads. Barometric condensers are now being replaced by non-contract
heat exchangers in various inorganic chemical plants. Installing
barometric condensers and later replacing them is expensive. of
barometric condensers in new plants is not a large additional cost item.
Chemical Treatment Systems
Equipment Costs
These systems, consisting of chemical reactors, clarifiers, thickeners,
and filters or centrifuges, are designed as integral units for complete
waste treatment. Installed equipment costs for chemical treatment
systems as a function of capacity are summarized below:
Clarifiers Filters or Total*
Capacity Reaction and Thick- Centrifuges, Costs
cu m/day $ $ $ $
38(10,000) 15,000 15,000 25,000 60,000
379(100,000) 25,000 40,000 25,000 150,000
3785(1,000,000) 37,500 75,000 200,000 500,000
37850(10,000,000) 50,000 200,000 750,000 2,000,000
*Includes engineering, land preparation, and installation. Does not
include land cost, storage tanks and disposal facilities, or other
auxiliary equipment.
These costs are for light slurry loads. For heavy slurry loads, such as
for titanium dioxide wastes, overall costs are several times greater.
311
-------
Chemical Costs
The costs for chemical treatments cannot be generalized. Most of the
chemicals used, however, are for neutralizations. Chemical treatments
costs depend on the chemical used and the amount required which varies
with the particular situation. The unit cost of the chemical is usually
known. Whenever feasible, neutralization of alkaline wastes is done
with sulfuric acid. As shown in Table 71, sulfuric acid costs only 30
to 40 percent as much as hydrochloric and nitric acid. In other words,
a dollars worth of sulfuric acid will neutralize 2.5 to 3.5-. times as
much alkalinity as a dollars worth of the other two acids. Cost for
sulfuric acid is approximately $33/kkg ($30/ton) . .
For acid wastes, the preferred neutralization materials are limestone
and lime. Limestone is the lower cost material at $7-ll/kkg ($6-
10/ton) ; but suffers the disadvantage of slower reaction, high
impurities, and lower obtainable pH. Lime costs are approximately
$22/kkg. Ammonia and sodium hydroxide are far more expensive than lime
or limestone, with 50 percent sodium hydroxide at $121/kkg ($110/t-on)
(100% basis), it can be seen why lime is preferable in most cases. '.-
For small usage or where solubility or character of precipitate 'i'-s
important, caustic soda or ammonia may still be employed. ' .•:••
Neutralizations with waste acids or bases can change the whole
structure. Waste sulfuric acid is often available at either no cost pit!.
the cost of freight. Waste lime, caustic soda or ammonia can sometime'^-"
be obtained at similar low costs. • '•/
." .':
Costs for neutralizations and other chemical reactions are simply
determined for special applications by multiplying the cost/weight of"
the neutralizing or reacting chemical by the weight stoichiometrically
required. Where specific experience is available, it may have been
found that 10 to 20 percent excess over stoichiometric quantities are
needed. In rare cases, several-fold excesses may be used to ensure.
complete reaction.
Settling Ponds and Vessels
Ponds for storage, emergency discharge or holding, settling of suspended
solids, or solar evaporation, are the most commonly employed treatment
and control facility in the inorganic chemical industry. Two
categories, (1) unlined ponds and (2) lined ponds are summarized in the
tables and figures of this section.
A third category, tanks and vessels such as thickeners and clarifiers,
are not widely used at present in the inorganic chemical industry as
contrasted to other chemical industries and sanitary treatment
facilities. As land becomes more costly and unavailable and treatment
and control requirements change, open tanks and vessels may see
312
-------
TABLE 71. Comparison of Chemicals for
Waste Neutralization
Alkaline Wastes
Neutralizing Material
Sulfuric Acid (50° Be)
Hydrochloric Acid (20°Be)
Nitric Acid (39.5°Be)
Relative
Chemical
Cost*, $
1.00
2.57
3.51
kg*** Reg'd/kkg Alkali'
CaCO3 Ca(OH)2
1260
2320
2100
1700
3140
2840
NaOH
1580
2500
2630
Acid Wastes
Neutralizing Material
Lump limestone, high Ca
Lump limestone, dolomitic
Pulv. limestone, high Ca
Oulv. limestone, dolomitic
Hydrated lime, high Ca
Hydrated lime, dolomitic
Pebble lime, high Ca
Pebble lime, dolomitic
Pulv. quicklime, high Ca
Pulv. quicklime, dolomitic
Sodium bicarbonate
Soda ash
Caustic soda (50%)
Ammonia (anhyd.)
Magnesium oxide
Cost*, $ H2SO4
kg*** Reg'd/kkg Acid11
.16
.00
.59
.37
.06
.50
.07
.87
.18
.97
20.65
13.08
9.96
5.90
3.90
1100
940
1100
940
790
650
600
540
600
540
1730
1190
1640
350
420
HCI
1480
1270
1480
1270
1070
870
800
730
800
730
2330
1600
2200
470
560
HNO3
860
730
860
730
620
510
460
420
460
420
1350
930
1270
270
330
"'Delivered cost including freight.
''Commodity weight.
''To convert numbers to Ibs. req'd/100 Ibs alkali or acid, multiply x 0.1 .
313
-------
increased use. Cost information on equipment of this type has already
been given in the chemical treatment section.
Unlined Ponds
The costs of constructing unlined ponds differ widely depending on the
circumstances. Since they cover large areas, the cost of the land
itself is a factor. Building a 200 hectare (500 ac) pond on prime
industrial land may cost $1 to 5 million just for the land itself. No
provision is made in this analysis, however, for such costs. It is
assumed that the land value is not a large portion of the cost. For
small ponds of less than U to 20 ha (10 to 50 ac) and land values of
$250 to $625 per ha ($100 to $250 per ac), this assumption is good, as
will be seen from the magnitude of the other costs.
Construction costs vary widely depending on the circumstances. Use is
often made of natural pits, valleys, ponds, lakes, etc., for minor
alterations, such as damming, dike building and leveling. Excavation is
easier in some localities than others.
Size of the pond is also a major factor in costs. Small ponds may be
dug and the excavated dirt used for dikes. Large ponds are usually
diked or dammed.
Assuming equal depths of two ponds, one large and one small, the volume
increases as the square while the dike length (and earth moving) is
increasing only linearly. Therefore, costs will be developed for small
ponds and then for large ones.
Small pond capital costs are given in Figure 76
Large pond costs developed from reference (27) are given in Figure 77.
Undoubtedly, many of these installations made use of natural topography
(lakes, basins, etc.) to avoid as much excavation as possible.
Nevertheless, the general cost levels and trends may be seen. As would
be expected from the diking costs varying by the square root of the
area, the pond costs per hectare above 200 ha (500 ac) change very
slowly.
Lined Ponds . .
To avoid excessive liquid seepage, ponds are often lined with clay,
concrete or other substances. Recently, however, a new class of lining
materials have come into use — rubber and plastic sheeting.
Essentially, costs for pond construction are the same as for unlined
ponds except for the sheeting material and installation. Therefore, the
costs may be estimated by adding the installed liner costs to the
previously determined costs for unlined ponds. The material costs for
the lining range from $1.00 to $6.00 per sq m (100 to 60£ per sq ft),
314
-------
POND AREA (HECTARES)
2315
POND AREA (ACRES)
FIGURE 76
CAPITAL COSTS FOR SMALL UNLINED PONDS
(REFERENCE (28), (29), AND (30))
r
500
POND AREA (HECTARES)
IOOO 1500
POND AREA (ACRES)
FIGURE 77
CAPITAL COSTS FOR LARGE UNLINED PONDS
(REFERENCE (27))
315
-------
depending on the material selected and the thickness of the sheet.(30)
Although thicknesses as low as 250 microns (10 mils) have been
discussed,(31) the most used thickness appears to be 750 micron (30
mils). For 750 micron (30 mils) PVC liners, the installed cost per sq m
is approximately $2.00.
The construction costs for small lined ponds are given in Figure 78.
These values may be conservative as far as film costs are concerned.
For large ponds, lined costs have been estimated by adding $2.00 per sq
m (200/sq ft) to the unlined costs. The results are shown in Figure 79.
Since a two hundred ha (five huftdred ac) lined pond costs $U to 6
million this approach for large scale waste treatment and/or storage
will require careful investigation before proceeding.
Solar Fvaporation Ponds
Lined solar evaporation ponds have been discussed in Section VII. Table
72 gives the costs for solar ponds as a function of evaporative
capacity. Table 73 gives costs per 3785 liters (1000 gallons)
calculated from Table 72 for comparison with treatment costs for other
processes. A pond and liner life of 20 years was assumed.
Carbon Adsorption
There are a few instances where organic materials are present in the
inorganic chemicals industry water wastes. These organic meterials may
be handled in many cases by conventional biological digestion sanitary
waste processes or they may be treated by methods such as carbon
adsorption.
Installation costs from the literature range from 50 to 200/3785/1 (1000
gal) treated. A cost of 150 was chosen as representative. This cost
includes 5 percent loss of efficiency upon carbon regeneration.
Combining capital costs from Figures 80 and operating costs from above,
overall costs are shown in Figure 81.
Ion Exchange and Demineralization
Ion-exchange and demineralization water treatments are widely used,
particularly for pretreatment of boiler, cooling tower, and process
feeds.
Ion exchange, as its name implies, replaces undesired ions with less
objectionable ones. Some of the ions removed in this way include
magnesium, calcium, iron, manganese, carbonate, nitrate, and sulfate.
Usually these ions are replaced by sodium or chloride ions. Total
amount of dissolved solids remains almost the same.
316
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TABLE 72. Capital Costs for Lined Solar Evaporation
Ponds as a Function of Capacity*
Evaporation—Rainfall Differential
Capacity
cu m/day(GPD)
38 (10,000)
189 (50,000)
378 (100,000)
945 (250,000)
1890 (500,000)
3785 (1,000,000)
2
Hectare
(Acres)
2.2 (5.6)
11.2 (28)
22 (56)
56(140)
1 1 2 (280)
220 (560)
Ft.
1
3
6
Capital
Costs
150,000
420,000
820,000
,960,000
,700,000
,650,000
4
Hectare
(Acres)
1.1 (2.8)
5.6(14)
11.2 (28)
28 (70)
56(140)
112(280)
Ft.
Capital
Costs
95,000
212,000*
470,000
1,010,000
1,960,000
3,700,000
6 Ft,
Hectare
(Acres)
0.8 (1.9)
3.7 (9.3)
7.5 (18.7)
18.7 (46.7)
37.3 (93.3)
74.8 (187)
Capital
Costs
80,000
220,000*
282,000
690,000
1,350,000
2,570,000
*Ponds of 10 acres and under tanke from Figure 74; those over 10 acres taken from Figure 75.
TABLE 73. Costs for Solar Evaporative Pond Disposal
Evaporative
Capacity
cu m/day (GPP)
38 (10,000)
379 (100,000)
3785(1,000,000)
20-Year Pond Life
Cost, C/3785 liters (<:/!, 000 Gal.)
Evaporation-Rainfall Differential
2 ft/yr 4 ft/yr 67F7yr
214
117
95
136
67
53
114
40
37
317
-------
no
no
no
«4(
no
nc.
**>
-
CO
40 •
to
POM) AREA (HECTARES)
OI«J45«T«8OIII2
POND AREA (ACRES)
FIGURE 78
CONSTRUCTION COST OF SMALL LINED PONDS
(REFERENCE (30))
900
POND AREA (HECTARES)
000 1500
POND AREA (ACRES)
FIGURE 79
CAPITAL COSTS FOR LARGE LINED PONDS
318
-------
200O 3000 5000 KUX» ZO.OOO 30JOOO 4O.OCO
CAPACITY (CU M/OW)
1.000,000
CAPACITY (GPO)
FIGURE 80
INSTALLED CAPITAL COST FOR
CARBON ADSORPTION EQUIPMENT
— 150
Q
1
£ 100
OT
i
o
8
"X.
-------
Demineralizations, on the other hand, by 'a combination of ionexchange
operations, actually remove almost all the dissolved solids.
Ion Exchange Costs
Since total dissolved solids of greater than 500-700 mg/1, regardless of
ion type, usually cause problems for potable, boiler, cooling tower,
process or other water use, ion exchanges are generally restricted to
treating low-total-dissolved^solids water. Two common treatment methods
are: (1) Sodium-hydrogen zeolite dealkalizers (2) Zeolite softeners
Estimated costs of ion-exchange operations as a function of dissolved
solids are shown below:
Zeolite Softening, Sodium-Hydrogen
Total Dissolved 0/3785 1 Dealkaliser,
200 5.7 6.U
500 10.8 9.5
750 15.0 12.2
While these values are only approximations, they do show that zeolite
"softening" or ion exchange with sodium chloride or sodium chloride plus
sulfuric acid is fairly low in cost even at the 750 mg/1 total dissolved
solids level. Ion exchange does not remove dissolved solids from waste
water. Therefore, Ion exchange units produce regenerant wastes that
have to be disposed of. With these considerations, ion exchange can be
virtually written off for waste treatment technology except for certain
specific harmful ion situations.
Demineralizatidn costs
Capital Costs The cost of demineralization equipment itself is fairly
consistent for the low solids fixed bed units used for most applica-
tions. For the specialty systems described in Section VII, particularly
at high solids, above 1000 mg/1, the costs are significantly higher for
a given capacity. Both the special nature of these units and the
influence of the higher resin volumes required to take the increased
loading increase capital costs. Installed capital costs can also differ
greatly depending on land availability, pretreatment facilities needed,
buildings, storage tanks, and engineering and contractor costs. The
installed capital costs developed in this section have been adjusted
using 33 percent of equipment costs for installation and 6 percent
increase per year in equipment costs. All values are in 1973 dollars.
They do not include resin costs which are covered in operating costSi
Values for capital costs were taken from literature references. Average
values are plotted in Figure 82.
320
-------
I.OOO.OOOr
2-STEP STRONG BASE
2-STEP WEAK BASE
HIGH TOTAL DISSOLVED SOLOS
11000-tCOO Ua/LI
LOW TOTAL DISSOLVED SOLIDS
(O-600MS/L)
900 1000 5000 KfXO
CAPACITY (CU M/OAY TREATED)
IO.OOO OO.OOO lflOO.000
CAFBCITY (GPD TREATED)
FIGURE 82
INSTALLED CAPITAL COST vs. CAPACITY
FOR DEMORALIZATION
( CONVENTdVAL DEV'.ERA1JZERS ARE REGENERATED WITH
SCOUM HYPW-'K A.-;D SULFi^C AC'O
2. HiGH EFF.CT'.CY L-'.'TS A*c ^ejEf.f^ArrQ W(J-H L(M£
AND SULFUR C ACID VWSTE
-------
A rule-of-thumb is that installed capital costs for conventional
demineralization units are about one-half those for reverse osmosis
installations for similar capacity.
Operating and Overall Costs
The operating costs for demineralizations are made up of the costs oxf;
(1) Resin; (2) Chemicals; (3) Labor and Maintenance.
For the higher dissolved solids levels, chemical costs are the primary
concern. These costs are shown in Figure 83. Overall costs are given
in Tables 74 and 75.
Reverse Osmosis Treatment Costs
The costs involved with waste treatment using reverse osmosis are given
comprehensive coverage in reference (49). Most of the costs for this
section were derived from this reference. References (50) through (56)
provided additional information concerning reverse osmosis costs and
performance.
The costs for reverse osmosis treatment include: capital equipment,
membrane replacement, pretreatment, power and labor plus maintenance
materials.
Installation Costs The capital costs for reverse osmosis installations
change significantly with plant size. Small units cost $1.00 to $1.50
per 3.78 I/day (GPD) while large units lower this cost to $0.50 or less
per 3.78 I/day as shown in Figures 84 and 85. These costs do not
include either extensive pretreatment or disposal facilities.
Membrane Selection and Life
The selection of the membrane material, either sheet or hollow fiber,
depends primarily on the nature of the waste to be treated and the
product water guality desired. In general, tighter (small pore size)
membranes have lower flux rates (I/ day per sq m of membrane surface)
than more open structured ones. Therefore, to obtain low-total-
dissolvedsolids product water, the area required for treatment of a
given I/day flow rate will be significantly higher than for an allowable
high-total-dissolved-solids product water. In turn, the increased
membrane surface area will increase the capital and membrane replacement
costs. This influence is shown in Figure 86 as it affects overall
costs.
Operating Costs
Membrane life is one of the major factors of operating costs. Currently
membrane life appears to be one to three years, with the average shifted
toward the one to two year interval for replacement. This short and
322
-------
TABLE 74. Overall Costs for Demineralization
FIXED BED 2-STEP DEMINERALIZATION
OJ
M
10
Installed
Labor and
Capital Resin Chemical Maintenanc
Capacity Amortization Costs Costs Costs
Treated <:/! 000 gallons <:/! 000 gallons <:/! 000 gallons
-------
TABLE 75. Overall Costs for DemineralizaHon
SPECIALTY PROCESSES ~ High Efficiency-Low Cost Regeneration Units
to
ro
Capacity
Treated
cu iVday(GPD)
Labor
Capital Resin Chemical Maintenance Overall
Amortization Costs Costs Costs Costs
$/l 000 gal Ions
-------
5.000,000,
IOOO IQPOO
CAPACITY (CU M/OAY TREATED)
100.000 1000.000
CAPACITY (6PD TREATED)
FIGURE 84
INSTALLED CAPITAL COSTS FOR
REVERSE OSMOSIS EQUIPMENT
8
40 no
400 IfiOO 4,000 10,000
CAPACITY (CU M/DAY TREATED)
40.000
IOOJOOO IPOOIXO
CAPACITY (GPD TREATED)
FIGURE 85
COSTS FOR REVERSE OSMOSIS TREATMENT
325
-------
(jj
40
g*
V)
a
co
O
<•>
O
0=2
U
X
20
15
< w 10
O *" 9
O O 8
S 7
• LP-HFF 250 PSI
FEED COMPOSITION (ppm)
Na 400
Ca 360
Mg 100
0 120
SO. 2000
HCO,
120
3100
SPIRAL WOUND
300 PSI
— DASHED LINES DENOTE /
_ MEMBRANE PERMEABILITIES, GFD/100 PSI
INDICATES STATE-OF-THE-ART MODULES
INDICATES DEPLOYMENT OF LOW PRESSURE MEMBRANES
CURRENTLY UNDER DEVELOPMENT
II I I I I I I
GESCO
10.0
_L
f I f I
20
30 40 50 60 70 80 90 100 150 200 300
PRODUCT WATER QUALITY, TDS, ppm
400 500 600
1000
FIGURE 86. TRADE-OFF BETWEEN MEMBRANE PERMEABILITY (FLUX)
AND SELECTIVITY (REJECTION AND PRODUCT WATER
QUALITY) FOR CELLULOSE ACETATE BASE MEMBRANES
(TO MGD PLANT @ 55% RECOVERY, 3100 ppm TDS FEED)
-------
variable life has restricted use of reverse osmosis in many otherwise
loaical applications.
Since modules constitute one-third to one-half of the capital equiornen4-
costs, the life of the modules is critical. Unfortunately, module
performance and life are also the most difficult features ol the unit ro
predict and control. For this reason, cost developments in this section
are based on a two (2) year life. As application experience increases,
improved membrane life will significantly reduce operating costs. Table
76 summarizes membrane replacement costs for two to three year lire.
Various chemical pretreatments are required to prepare feedwater for
passage through the membrane units. Included in these pretrtatments are
pH adjustment, such, as acid addition to eliminate carbonate scaling,
pulfate scalincj control through addition of sodium hexametaphosphate,
and chlorination for organics.
"Low energy requirement is one of the major advantages ot the reverse
osmosis process. The primary energy requirement is for hign pressure
pumps.
Labor and maintenance costs shown in Table 77 are taken irom reference
(49). Table 77 summarizes the operating costs. Figure 65 combined all
the information developed into overall reverse osmosis treatment costs.
These values are based on conservative engineering and industrial
calculations and assumptions. Membrane life of two years is assumed.
straioht line 10 year depreciation and 6 percent money are used in the.
calculations.
327
-------
TABLE 76. Reverse Osmosis — Membrane Replacement Costs
Vglume_Treated
cu m/day GPP
38
95
189
379
945
1,890
3,785
18,900
37,850
10,000
25,000
50,000
100,000
250,000
500,000
1,000,000
5,000,000
10,000,000
g/1000 gal.
2_Yr. Life
Present
Future
05
45
45
38
38
30
30
22
15
Present
22
22
22
20
20
15
15
12
8
30
30
30
25
25
20
20
15
10
Taken from Reference (49), p. 108. converted to
treated basis plus two (2) year life adjustment.
Future
15
15
15
13
13
10
10
8
5
cu m/day and GPD
TABLE 77. Reverse Osmosis — Operating Costs
Volume_T reated
cu_m/day GPD
38
95
189
379
945
1,890
3,785
18,900
37,850
10,000
25,000
50,000
100,000
250,000
500,000
1,000,000
5,000,000
10,000,000
Power*
6
6
6
6
6
6
6
6
6
(g/1QOO gal. ora 3785 1 Treated
Labor Plus
Maintenance Total
Chemicals** Materials Cost
4
4
4
4
4
4
4
4
4
28
20
15
10
7
5
4
2
15
*At 10 per kwhr.
**Will vary depending on pretreatment required.
***Additional breakdowns in reference cited above.
38
30
25
20
17
15
14
12
11.5
328
-------
Evaporation Costs
Although there are many different designs and variations of evaporative
equipment, four basic types can be used to cover the needs of th°
inorganic chemical field: (1) single-effect evaporators; (2) multi-
effect evaporators; (3) high efficiency vertical tube and multi-effect
flash evaporators; and (4) low energy specialty evaporators. Costs for
these types of equipment and their operation are given in the following
subsections. Descriptions of these units were given in Section VII.
Equipment Selection
Each of -»-hese types of evaporators has its own performance area, as
shown in Table 78. Figure 87 gives the energy requirements of each as
well as other treatment techniques as a function of dissolved solids
content..
The selection of evaporative equipment depends on the job requirements.
For high volume, low solids stream concentrations the VTE, or multi-
flash type units should be used. Ninety percent or more of the water
can be recovered as high purity product with relatively low energy
requirements. The remaining five to ten percent can be more
economically removed by recirculating evaporators or dryers. Although
energy requirements are high per kg of water removed for single effect
evaporators and dryers, the total energy requirement and capital costs
for this step are relatively low. High-volume, highsolids-content
streams may be handled similarly except that conventional multi-effect
evaporators should be used for the first concentration.
Low Energy Specialty Evaporator Costs
V
Capital costs for a specialty low energy unit, the flat plate vapor
compression evaporator, are given below.
Capacity Installed Capital
cu_m/day_ __ (GPD) ____ Costs, $ ____
379 (100,000) 635,000
850 (225,000) 1,350,000
1890 (500,000) 2,500,000
Larger capacities would currently be made up of multiple smaller units.
Operating costs for this unit arise from electric power, pretreatment
chemicals, and labor.
Unlike most evaporators, this unit depends on an electrically driven
compressor instead of steam for its energy, therefore, operating cost is
directly influenced by the electrical power costs in the area. This
cost may range from $0.003/kwhr to over $0.01/kwhr. For industrial
applications, operating power costs for this study are taken as
329
-------
TABLE 78. Evaporator Characteristics
Character-
istics
Re-
circulative
Evaporator
Multi-
effect
High
Efficiency
Vertical
Tube
Evaporator
Low
Energy
Specialty
Evaporator
Effects
Evaporative
energy,
kg caj/kg
(Btu/lb)
Optimun
concentration
range, % by
weight of
solids
1-3
'222-555
(400-1000)
2-6
100-333
(180-600)
20 to max. 10-50
10-20
42-56
(75-100)
1-10
15-30
19-56
(35-100)
1-10
Ability to
handle heavy
crystallizing
or suspended
solids food
Optimum
capacity
range
General
costs
Excellent
Best, for
small capa-
city below
5000 GPD
Relatively
low
Good,
can be
easily
equipped
for re-
circulation
Good over
wide capa-
city range
10,000-
2,000,000
GPD
Inter-
mediate
Poor,
not
operable
Mainly for
high capa-
city more
than
1,000,000
GPD
High
Good,
for calcium
sulfate and
other slurries
Mainly for
high capa-
city more
than
100,000
GPD
Highest
330
-------
% WATER RECOVERY
GJ
U>
1,000
REPRESENTATIVE
WASTE WATER
TYPICAL GYPSUM
SATURATION LIMIT
DISTILLATION
REVERSE
OSilOSIS
ELECTRO-DIALYSIS
1,000
kg ca I/kg
10,000 100,000
TOTAL DISSOLVED SOLIDS (ppm of concentrate)
FIGURE 67. ENERGY COMPARISON FOR DISSOLVED SOLIDS REMOVAL
1,000,000
-------
$0.01/kwhr. The amount of power required depends on the evaporative
situation. The following table gives estimated power as a function of
total dissolved solids in mg/1 in the concentrate.
Concentrate TDS* (mg/1)
10,000
50,000
100,000
200,000
kwhr/1,000 gal
or 3785 1 Treated
60
65
100
250
*Total solids, including those suspended in the slurry,
may be several times greater than the dissolved solids.
The above correlations are approximations — useful for operating cost
calculations. Operating and overall costs in 0/3785 liters (1000
gallons) for an 850 cu m/day (225,000 GPD) unit are given below:
Concentrate Power
JDS*x_mg/l_ (kwhr/1000 gal) Chemicals
10,000
50,000
100,000
200,000
60
65
100
250
3
3
3
3
Operation
and
Maintenance Total
52 115
52 120
52 155
52 305
*Since sparingly soluble water contaminants such as calcium
sulfate and silica precipitate with concentration, total
solids are usually much higher.
Concentrate
TDS mg/1
10,000
50,000
100,000
200,000
Capital
0/1,000 Gal.
_or_37J55_l__
257
257
257
257
Operation
0/1,000 Gal.
_or_3785_l
115
120
155
305
Total
0/1,000 Gal.
_or_3785_l_.
327
377
412
562
These overall cost values are admittedly conservative, but are
consistent with the basis used for other calculations of this report —
industrial 10 year depreciations and higher cost electric power than
would be available to many current users. Low cost power and 35 year
capital writeoffs would bring the overall costs down to approximately
$2.00/1,000 gallons or 3785 1 treated.
It should also be emphasized that the power requirement correlation with
total dissolved solids neglects the suspended solids portion of the
332
-------
recirculated slurry. Since many dissolved solids such as calcium
sulfate are only sparingly soluble in water, concentration causes them
to precipitate and form slurries. The unit is designed to handle sucii
slurries up to total solids contents of 35 to 50 percent (at which point
the total dissolved solids might be one percent or 10,000 rag/1). The
critical difference here is that dissolved solids raise the boilinq
point of the solution while suspended solids do not appreciably affect
it. The ability to handle slurries is one of the key tecianology
advantages over multi-flash and vertical tube evaporators which are
discussed next.
High Efficiency Multi-Flash and Vertical Tube Evaporators
Conventional Multi-Effect Evaporators
For the heavy-duty, very high-solids evaporations, industrial type
multi-effect evaporators are indicated. The inorganic salts in seawarar
and inorganic chemical industry are very corrosive. Even cupro-nickel
and stainless steel alloys may not be sufficient for many of the
solutions involved. Therefore, for this section, costs are given for
solid nickel, titanium and tantalum materials, as well as stainless
steel. Nickel construction raises the cost significantly, but will
provide reliable service demanded for industrial applications.
In selecting the optimum number of effects, a balance has to be made
between equipment costs and operating costs. If the addition of an
effect will not pay for itself in lower steam costs within approximately
three years, the effect will probably not be added. It is rare that
more than six or seven effects can be justified in this manner. (This
is particularly true because of the high dissolved solid solutions or
waste involved). Figures 90 and 91 show the interrelationships between
number of effects and capital cost and steam usage, respectively.
Capital costs may be calculted rather quickly and directly from Figure
92:
Treated Total Installed
cu_m/day_ (GPD) Capital Cost, $
378 (100,000) 667,000
945 (250,000) 1,530,000
1890 (500,000) 2,800,000
3785 (1,000,000) 5,470,000
Analogous values for stainless steel and other construction material
capital costs may be similarly derived.
333
-------
r
S 900
3«oc
IJ
9
4000 KWOO
PLANT SIZE (CU M/QAY TREATED)
4ftDOO
(000JOOO
PLANT SIZE (GPO TREATED)
FIGURE 88
INSTALLED CAPITAL COSTS vs. CAPACITY FOR HIGH
EFFICIENCY VTE OR MULTI-STAGE FLASH EVAPORATORS
J2300
104000
CAPACITY (CU
lOOQOOO
CAPAcrrv (GPO)
10,000000
FIGURE 89
OVERALL AND TOTAL OPERATING COSTS
FOR VTE AND MULTI-FLASH EVAPORATORS
334
-------
-t-r-
U1
4 6
Number of Effects
EVAPORATION
Figure 90. . Capital Costs Vs. Effects
for Conventional Multi-
Effect Evanorntnrs.
-------
10
EVAPORATION
1000
600.000 = .*"
Figure 91. Steam Usage Vs. Effects for Conventional Multi-Effect Evaporators
-------
IJOOOOOO
IjOOO IQOOO
TOTAL HEATING SURFACE (SO M)
wooo
10,000 loqooo
TOTAL HEATING SURFACE (SO FT)
FIGURE 92
CORRELATIONS OF EQUIPMENT COST WITH
EVAPORATOR HEATING SURFACE
O TOO
Q- 600
1 900
1000 3000
CAPACITY (CU M/DAY TREATED)
5OOO 4000
CARACITY (GPO TREATED)
ltOOO.OOO
FIGURE 93
OVERALL COSTS FOR 6-EFFECT EVAPORATOR
TREATMENT OF WASTE WATER
337
-------
Operating costs are made up of steam value, labor and maintenance.
Chemical pretreatment costs are usually minimal. Operating costs are
summarized below for 6-effect evaporators.
Overall costs for all-nickel and stainless-steel-6-effect evaporators
are given in Figure 93.
Steam Labor and
Costs in Maintenance Total Costs
Treated Treated 2/3785 1
-------
Treated
38
189
379
945
1890
3785
Treated
10,000
50,000
100, 000
250,000
500, 000
1,000,000
Installed
Capital
8,000
28,000
45,000
80,000
146,000
267,000
Capital
Writeoff
0/3785 1
34
24
19
14
12
11
Operating
Costs
0/3785 1
564
551
545
539
536
533
Overall
Costs
0/3785 1
598
575
564
553
548
544
Basis: Installation Costs -- 100^ of equipment capital for 38
and 189 cu m/day (10,000 and 50,000 GPD) size, 50* for
379 cu m/day (100,000 GPD), 33% above 379 cu m/day
(100,000 GPD) .
15% Capital writeoff/yr.
4* Capital cost/yr for maintenance materials.
90% Evaporation.
Steam cost — $0.70/1000 Ibs or $0.70/454 kg.
- Labor cost/1000 gal or 3785 liters treated (350 day/yr
operation): 10,000 GPD - 300 (38 cm/d)
50,000 GPD - 200
250,000 GPD - 100
500,000 GPD - 80
(189 cm/d)
(945 cm/d)
(1890 cm/d)
1,100,000 GPD - 50 (3785 cm/d)
Similar values for all nickel, titanium or tantalum construction
are:
cu m/day
38
189
378
945
1890
GPD
10,000
50,000
100,000
250,000
500,000
Installed
Capital
16,000
68,000
133,000
300,000
532,000
Capital
Writeoff
0/3785 1
Total
Operating
Costs
0/3785 1
3785 1,000,000 1,060,000
69
58
57
52
46
45
574
561
555
549
545
542
Overall
Costs
0/3785 1
643
619
612
601
591
587
Basis: Same as previously shown except 33% of capital costs
used for installation estimates for all capacities.
These figures show that single-effect evaporation costs are
largely steam. Also, materials of construction are not very
important in their influence on overall costs. All nickel,
titanium, tantalum or other high cost materials of construc-
339
-------
tion are often needed and can be used without undue penalty.
The high overall costs per liter treated also indicate that
single-stage evaporators are restricted to small capacities.
For example, at the 3785 cm/day (1,000,000 GPD) capacity, yearly
overall cost for stainless steel equipment is $1,910,000. Com-
parable multi-effect and VTE costs are $583,000 to $1,400,000
yearly, obviously the higher efficiency units would be used
whenever possible. At the 379 cu m/day (100,000 GPD) level, comparable
costs are $198,000 per year for single effect, $72,200/yr. for six-
effect, and $78,500/yr. for 14-effect. For this case, there is still
approximately $120,000/yr savings in going to multi-effect evaporators.
Single-effect evaporators would normally be used in the capacity range
of 18 cu m/day (10,000 GPD).
Mechanical Drying Costs The crystallized, suspended or dissolved solids
in the previous evaporation section can either be recycled, sold, or
disposed of in their concentrated form, or, they may require further
treatment. Whenever possible, suspended solids should be dewatered by
centrifuging or filtration. These relatively low cost treatments may be
all that is needed, or reduction to full dryness may be required. When
full dryness is required, the filter cakes, centrifuged solids, and
concentrated solids may be subjected to conventional thermal drying.
Heating may be by gas, oil, or steam. Types of dryers include rotary
drum dryers, screw type mechanical dryers, scraped surface tunnel dryers
and heated evaporation pans.
Capital costs and labor costs are minimal (labor and materials are
estimated to be at $0.11 to $0.33/kkg ($0.10 to $0.30/ton)) of product
for small dryers (Reference (71)) as compared to the energy cost.
Taking energy costs as $0.50 per 252,000 kg cal (million Btu) (gas or
oil combustion) and an energy utilization efficiency of 50 percent,
drying costs are $1.00/454 kg (1000 Ib) of water evaporated.
Drying costs as a function of solids content are given below:
Drying Costs, Drying Costs,
% Solids in Feed 0/454 kg 0/3785 1
90 10 Dry Basis
80 20 Dry Basis
70 30 Dry Basis
60 40 Dry Basis
50 50 420
40 60 500
30 70 580
20 80 600
Aside from the energy costs involved, there are practical drying
problems with common dissolved salts such as calcium chloride, potassium
340
-------
chloride, and magnesium chloride. These can be dried but they hold
tenaciously to residual water and must be given special handling
techniques involving drum flakers, pan evaporations, and other processes
well known to industry.
Deep Welling Costs
The capital costs for injection wells vary over a very wide range --
from $40,000 to more than $1,000,000. The costs depend on factors such
as well depth, geology, well hole size, care in drilling, well con-
struction, geographical location, pretreatment requirements,
instrumentation and monitoring, corrosion problems, injection pressure,
and maintenance.
The principal cost factors in well construction are drilling contractor
costs and casing and tubing costs. These two factors comprise
approximately two-thirds of the total construction costs. The larger
and deeper the hole, the higher the contractor costs will be.
Surface eguipment such as pumps, filters, tank, piping, and
instrumentation can vary from 50 percent of well construction costs to
100 percent or more. 27 atmospheres reguire more expensive pumps.
Corrosive liquids require more expensive materials in the liquid
handling equipment.
The average deep well capital and operating costs determined from a
recent comprehensive survey (Reference (77) are: capital cost —
$305,000; operating costs — 302/3785 1 (1000 gal).
Operating costs for deep well disposal range from 42/3785 1 (1000 gal)
to $2.20/3785 1 (1000 gal). The lower costs are for shallow wells, low
injection pressures, minimum pretreatment, relatively low corrosiveness,
and a minimum of monitoring and instrumentation. The higher operating
costs involve deep wells with high injection pressures, extensive
pretreatment, high maintenance costs, extensive monitoring and
instrumentation, and corrosion resistant equipment. In any cost
calculations involving deep wells, as discussed in Section VII, either a
backup well or alternate disposal facility is necessary. This will
increase the average capital cost to approximately $500,000 (for a
single-well operation).
Calculating overall costs for deep well disposal at a 1890 cu m/day
(500,000 GPD) rate and using the 15 percent capital amortization used
for otheik treatment and control methods gives an overall cost of
732/3785 1 (1000 gal) .
Economic land disposal of soluble solids is one of the more difficult
environmental problems facing the inorganic chemical industry. If it is
not solved, a number of chemicals may have to be produced in favorable
341
-------
geographical areas (for solar plan or land storage) or wastes will have
to be shipped to those areas.
Solids Wastes Disposal Costs The slurries, water soluble solids and
water insoluble solids obtained from control and treatment of inorganic
chemicals industry water-borne wastes have to be contained, or disposed
of, in a safe and economical manner.
There are two key considerations: (1) Are the solids soluble or
insoluble in water: (2) What is the net evaporation-rainfall situation
for the area?
Insoluble Solids Provided that the solids are insoluble in water, most
solid wastes from the inorganic chemicals industry may be land dumped or
land-filled. Slightly soluble materials such as calcium sulfate may be
handled this way (although not necessarily with complete justification).
Costs are $0.22 to $0.66/kkg ($0.20 to $0.60/ton) of solids (Reference
(71)) -- for simple dumping or landfilling. Figure 94 gives a breakdown
of complete landfilling costs. Large scale operations without cover
cost less than $l.ll/kkg ($1.00/ton). If cover is involved for appear-
ance or zoning requirements, the costs may increase to $1.05 to
$2.20/kkg ($1.50 to $2.00/ton).
Soluble Solids
If the evaporation-rainfall situation for the disposal area is favorable
(as is the case for much of the southwestern U.S. and some other areas
of the country) , then landfill in an impervious, lined pan is feasible.
Costs for this operation are similar to landfill with no cover
(Reference (71)) — $0.22 to $0.66/kkg ($0.20 to $0.60/ton).
If, as is the case for most of the U.S., the evaporation-rainfall
balance is unfavorable (more inches of rain than evaporation per year)
then ocean dumping or waterproof containment must be practiced.
Ocean dumping of industrial wastes in 1968 involved 4,200,000 kkg
(4,690,500 tons) at an average disposal cost of $187/kkg ($1.70/ton) for
bulk wastes and $26.40/kkg ($24/ton) for containerized wastes. Since
soluble solid wastes for the inorganic chemicals industry are mainly
sodium chloride, sodium sulfate or other common salts, the solid wastes
would not have to be containerized.
•t
tt
Landfilling of containerized soluble solids in plastic drums or sealed
envelopes is practicable but expensive. Blow-molded plastic drums, made
from scrap plastic (which is one of the present major problems in solid
waste disposal) could be produced for $ll-22/kkg ($10-20/ton) capacity
at 227 kg (500 Ibs) solids per drum and a rough estimate of $2.50-5.00
cost/drum. A more economical method, particularly for large volumes,
would be sealed plastic envelopes, 750 microns (30 mils) thick.
342
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0
D)
c
o
C/J
O
o
8
1
0
Total cost per ton
cover material purchased
at $1.50/cu.yd.
I ! 1
.-- Total cost per ton
cover material on site
Cover material purchased
at$1.50/cu.yd.
Landfill equipment
Landfill labor
Cover material on site
0
300 600 900
Solid wastes, ton/wk. (six-day operation)
(X 0.907 = kkg/week)
1.200
Figure 94. Disposal Costs for Sanitary L-andfills
343
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At $1.10/kg (500/lb) of film, low density polyethylene costs about 100
per 0.0929 sq m (1 sq ft). Using the film as trench liner in a 1.8 m (6
ft) deep trench 1.8/m (6/ft) wide, the perimeter (allowing for overlap)
would be approximately 7.5 meters (25 feet). At a density of 1.6/gm/cc
(100/lb/cu ft) for the solid, costs of plastic sheet/kkg would be $2.00
($1.75/ton). With sealing, the plastic envelope cost would be
approximately $2.20/kkg ($2/ton). With landfill costs of $2.20/kkg
($2/ton) additional, the total landfill disposal costs would be about
$4.40/kkg ($4/ton).
The above figures for soluable disposal using plastic containers, bags
or envelopes are only rough estimates. Also, the technology would not
be suitable for harmful solids or in situations where leaching
contamination is critical.
Ocean Barging Costs References (81) through (84) have been used to
establish capital operating and overall costs for barging of difficult
or expensive-to-treat, water-borne industrial wastes.
The cost of a 4500 kkg (5,000-ton) capacity barge in 1973 dollars is
approximately two million dollars. New docking, storage tanks, pumps,
piping and other shore facilities may be 50 to 100 percent of the barge
cost, but are not included in these cost developments, because in many
plants these auxiliary facilities are already available. In a new
plant, or a major conversion, these costs could add $1.00 to $2.00 per
3785 liters (1,000 gallons) to waste disposal costs.
Overall costs for a 4500 kkg (5,000 ton) barge are approximately $4.50
per 3785 liters (1,000 gallons) of waste disposed (updated References
(81) and 84)). A rough breakdown of these overall costs is tug rental,
50%, labor and maintenance, 20%, and amortizations (15%/yr), 30%. Using
the above breakdown of overall costs, operating costs for other disposal
and treatment techniques would be $3.15/3785 liters (1000 gallons).
Treatment Costs for Ancillary Water-Borne Wastes
In many plants of this study ancillary wastes such as boiler blowdowns,
cooling tower blowdowns, ion exchange regenerants, and contributions
from air purification equipment, are either the sole or dominant
contributors to water-borne wastes coming from the plant. Rarely is
removing these wastes from plant effluent water considered part of the
treatment of waste abatement process costs.
Air-Borne Waste Abatement Costs Five chemicals of this study have been
selected for specific cost analysis. The circumstances for each are
explored.
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Sulfuric Acid
Reduction of sulfur dioxide in the stack gas of sulfur-burning and regen
sulfuric acid plants to specified limits is expensive for most existing
plants. In each of two plants of this study (113 and 023) over
"52,500,000 has been spent for this purpose alone. As regulations
tighten, other plants will have to be modified similarly. The nature of
these modifications should be determined by the overall costs and
performance of the sulfur dioxide unit considered. For the $2,500,000
installations mentioned above, reduction of the water-borne wastes
without such an installation would require approximately *80,000
additional capital investment ($20,000 for evaporation; $20,000 for
filter or centrifuge plus 100 percent addition for pumps, piping,
auxiliaries, engineering and installation) and a roughly estimated
overall cost, of $25,000 per year. Recovered sodium sulfate at
$38.50/kkg ($35/ton) would return approximately $100,000/year product
value. A profit could be realized, therefore, on the installation of;
the additional equipment and instead of having a water-borne wasteload,
useful product would be available for sale.
If a sulfuric acid producer does not choose to follow the path of
scrubbing sulfur dioxide from the stack gases, producing water-borne
wastes and then eliminating them, it will undoubtedly be more profitabl-
to recycle sulfur dioxide which should have a recovered sales value of
approximately $50/kkg ($45/ton) and eliminate the expense of sodium
hydroxide or other chemicals.
Both add-on double adsorption systems and other processes which have no
water-borne wastes exist. New plants all use the double adsorption
processes.
Existing plants should be free to use any sulfur dioxide abatement
process provided that there is no final water-borne waste contribution.
Those that produce these wastes should also provide for their removal as
part of the process and process costs.
Calcium Oxide and Hydroxide
The lime process has no waste water. The only contribution is from
stack scrubbers which collect the lime dust in water.
Current practice is to settle out solids from the scrubber water in
ponds and possibly neutralize this effluent before discharge to surface
water. A large lime plant which currently follows this general type of
procedure (057) plans to install a cyclone recovery and calcining unit
on the waste stream at a cost of $750,000. Cost of installation will be
covered by product value obtained. This will remove almost 100* of the
suspended solids. Some dissolved solids remain. Calcium oxide is
soluble to the extent of about 1000 mg/1. The water should be recycled
for closed loop scrubbing and would therefore be zero discharge.
345
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A second approach, which escapes water-borne waste and waste recovery
problems, is dry bag collection. The exemplary plant of this study has
no water effluent and uses dry bag collection systems. Installation
cost was $675,000 with annual operating costs of $37,500. Just as for
sulfur dioxide wastes from the sulfuric acid process, lime process dusts
should be collected by any effective abatement process provided that
there is no final water-borne waste contribution. Those processes that
produce these wastes should also provide for their removal as part of
the process.
Calcium Carbide There is no water-borne process waste from the calcium
carbide manufacturing process. The only contributions are ancillary
wastes — cooling tower blowdowns, ion exchange regenerants and gas
stream scrubbings.
For water scrubbers, the water effluent needs to be isolated, suspended
solids removed by ponding or chemical treatment, alkalinity neutralized
and a closed loop recycle instituted to avoid dissolved solids
discharge. Capital costs for a large plant adjusted to 1973 prices are
approximately $750,000 for the scrubber system, $112,000 for
improvements, plus a thickener and settling ponds that will bring the
total cost up to $1,000,000. No wastes are recovered and recycle is
possible but would reguire equipment modification. Therefore, over
$1,000,000 investment is needed to water-scrub without waterborne waste
with both capital and operating costs being losses.
In contrast, the exemplary plant of this study uses dry bag collection
techniques throughout. Collection and reuse of 10 percent of the raw
materials from these dust collectors makes installation profitable, and
there are no water-borne wastes involved.
Chlorine
The options of what to do with chlorine coming from the tail gas of a
chlor-alkali or Downs cell sodium plant are numerous, but dry bag
collection is not one of them. In contrast to the dusts from the first
three processes discussed, chlorine is a reactive and noxious gas. It
is soluble in water and forms hypochlorites with water or basic
materials present such as sodium hydroxide or calcium hydroxide.
The hypochlorites are bleaches and may be sold. They are also reactive
and can be used in the treatment of other chemical wastes such as
cyanides. This is done in exemplary plant 096. Sodium hypochlorite may
also be catalytically decomposed to decomposition and reuse, but many
plants simply discharge this reusable material as waste effluent. This
should not be allowed. It must be avoided if the zero discharge limits
recommended for Level II are to be met. Removal later from the waste
stream will be expensive.
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Another method for direct utilization of tail gas chlorine is direct.
burning with hydrogen to produce hydrochloric acid. Exemplary plan- 057
is olanning this approach at an estimated capital investment of
*<*30,000. Return on investment looks good from the standpoint of
product value and decreased sodium hydroxide usage.
with all of the above low cost options, there is no reason for ever
finding chlorine tail gas wastes in water effluents from the plant.
Aluminum Chloride
The aluminum chloride process has no water-borne wastes, but condenser
gas scrubbing removes residual chlorine gas and entrained aluminum
chloride fumes. Two exemplary plants (152 and 125) of this stuay avoid
any water-borne wastes as discussed in Section VII. Costs for a
generalized treatment process are shown below to illustrate the dollar
values involved. 2.25 kg (5 Ib) of chlorine per 0.907 kkg (ton) of
produc- in a 18 kkg/day (20 ton/day) plant, treatment costs are
develooed below for neutralization with sodium hydroxide. Sodium
hydroxide costs are estimated to be $70rOOO/yr. Also, 195 kg/day (430
Ib) of sodium chloride and 53 kg/day (117 Ib) of aluminum hydroxide are
formed. The volume of neutralized solution is approximately 9461/ day
(250 ctal/day) . Installed cost for a 379/1 (1000 gal) neutralizing,
settling and hypochlorite decomposition system plus a small
recirculating single-effect concentrator and crystallization system
would be approximately $25,000. Operating costs including steam,
electricity, disposal of solid wastes, labor and maintenance, and
chemical costs would be approximately $12,000/yr. Overall costs of
capital writeoff plus operating costs would be approximately »16,000/yr
or sliqhtly more than $2.20/kkg ($2/ton) of product.
Boiler Slowdowns, Cooling Tower Blowdowns, and Ion-Exchange Regenerants
Treatment Systems and Their Costs In many chemical plants,
blowdowns, and water treatment wastes are larger in quantity than
process wastes. This occurs for sulfuric acid, nitric acid,
electrolytic hydrogen peroxide, calcium carbide, phosphoric acid, and
sodium tripolyphosphate. As process wastes a'.c- reduced, more chemicals
will join the list. Therefore, these wastes should not be ignored.
Present water treatment facilities in existing plants are usually not
designed for zero discharge of water-borne wastes, nor are they designed
for complete closed cycle operation. Dissolved solids are the only
water contaminants which involve appreciable treatment problems, costs
and energy and it is in this area that present water treatment
facilities are inadequate. The generalized water treatment facilities
given in Figure 75 earlier in this section provide three treatment
techniques for removing dissolved solids from makeup and recycle water-
demineralization, reverse osmosis and evaporation. It is assumed from
the overall treatment model given in Figure 74 (of which Figure 75 is a
347
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detailed portion) that suspended solids and toxic materials have already
been removed. Figure 95 gives the dissolved solids concentration range
over which each type of treatment technique is economically feasible.
Costs for different flow rates and dissolved solids contents are given
in Table 79. This table shows that if all the incoming and recycle
water and blowdowns are less than 1000 mg/1 total dissolved solids then
demineralizations can be used economically from 1000 mg/1 to 3500 mg/1.
Specialty demineralization systems are favorable, if available. Most
blowdowns are in the 750 mg/1 to 3500 mg/1 range. If specialty systems
are available, they can be economically used. Regenerants disposal adds
to the overall demineralization costs. With these costs added, the
specialty demineralization and reverse osmosis plus evaporation
treatment costs are nearly equal in the 1000 mg/1 to 3500 mg/1 range.
If any of the streams coming into the treatment area have greater than
3500 mg/1 total dissolved solids, then reverse osmosis and/or
evaporation are usually the only treatment approaches.
New Plants should have a central integrated water treatment area with
all the necessary equipment to eliminate water-borne discharges,
including blowdowns and ion exchange regenerants.
A model plant example is shown in Table 80 to illustrate needed
equipment and costs for treatment.
In addition to the cost of treating the waste streams, approximately 36-
45 kkg (40-50 ton) per day of solids must be disposed of. Disposal
costs for these could range from $1.10 to $li.OO /kkg ($1 to $10/ton).
A centralized treatment system as described gives not only zero water-
borne waste but also supplies all the demineralized water needed for
boilers, operation of cooling water towers at 95 to 98 percent recycle,
and reduces process water wastes. Since the treatment equipment is all
highly automated, labor costs are also low*
Geographic Influences on Treatment and Control Costs
Treatment and control practices and costs for the inorganic chemicals
industry depend largely on plant location.
Ocean dumping is economically feasible only for plants with easy access
to the ocean. Even a difference of being located directly on ocean
shores as contrasted to being 80 to 160 km (50 to 100 miles) up a bay or
river can change barging costs by a factor of two. Ocean barging for
titanium dioxide wastes may be as little as $5.50 /kkg ($5/ton) of
product for well-suited plants. Costs may rise to $22-$44/kkg ($20 to
$40 /ton) for others requiring more capital expenditures and longer
barging distances.
Deep-well disposal is geologically feasible in some parts of the United
States but not in others. Since deep-welling is sometimes the lowest
cost, if not the only, feasible disposal method practicable, ability to
348
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Treatment
Small Waste Streams
<379 cu m/day (<100,000 GPD)
Ion
Exchange
I
Less than 1000 mg/1
Large Waste Streams
>379 cu m/day (;100,000 GPD)
Less than 1000 mg/1
Conventional
Demineral-
ization
1 Up to 1000 mg/1
••;] Up to 1000 mg/1
Demineral-
izaticns
Up to 4000 mg/1
Up to 4000 ing/1
Reverse
Osmosis
500 to 10,000 mg/1
500 to 10,000 mg/1
Single
Effect
Evaporator
\_/'/--///////}( 10/OOP ng/3- to Max Cone. V////.J
Not Economical - Initial By Multi-
Effect Evaporators
Multi-
Effect
Evaporator
//' 1000 mg/1 to 100,000 mg/1
> 1000 mg/1 to 100,000 mg/1
Solar
Evaporation
1000 mq/1 to Max Cone.
1 1000 mg/1 to.Max Conn,
Chemical
Precipitation
5 Percent Total Dissolved Solids
1 Percent Total Dissolved Solids
—l 1 ! i
10 20 30 40
Percent Total Dissolved
Solids
50
10 20 30 40
Percent Total Dissolved
Solids
50
Figure 95. Treatment Applicability to Dissolved Solids Range in Waste Streams,
-------
TABLE 79. Cost Estimates for Different Treatment
Reverse Osmosis
Flow Demineraiizatiort + Evaporation
(GPD) Costs, $/day Gost^ $/day
100 mg/iifef T6taj Dissolved Sdlids
Conventional Fixed-Bed
38(10,00$ 4 20
379000,000) 31 142
#85(1,000^000) 220 1005
37;«500 0,000,000) 2000 6000
1000 mg/liter Total Dissolved Solids
Conventional
Fixed-Bed
13
121
1120
10,000
3500 mg/liter Total
Specialty
Systems
7
43
335
x-3000
Dissolved Solids
20
142
1013
6275
38(10,000)
37?(100,000)
3785(1,000,000)
3^850(10^000,000)
Special fry Systems
38(10,000) .12 20
379(100,000) 96 142
3/85(1,000,000) 861 1013
37,850(10,000,000) 8000 6275
10,000 mg/liter Total Dissolved Solids
38(10,000) Costs are very high. This 20
37
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TABLE 80. Model Treatment Plant Calculations
Design and Cost Basis
Waste
Category
Process Water
Cooling Tower Slowdown
Boiler Slowdowns
Air Pollution Control
Makeup Water
Equipment-
Needed
Demineralizer
Reverse Osmosis Unit
Multi-Effect Evaporator
2-Single-Effect Evaporators
Rotary DrumFilter
Centrifuge
Waste Treated
Process Water
Cooling Tower Slowdown
Boiler Blowdown
Make-Up Water
Air Pollution Control
Net Cost
cu m/d (GPP)
379(100,000)
38(10,000)
19(5,000)
38(10,000)
189(50,000)
cu m/d (GPP)
379(100,000)
379(100,000)
94(25,000)
38(10,000)
Total
Pissolved
Solids, mg/l
10,000
1,000
500
10,000 (Recoverable at $33/kl<9
or $30/ton.)
300
Capital
Cost, $
60,000
80,000
60,000
32,000
25,000
25,000
Overall Costs/Pay
Total $282,000
$ 142
$ 45
$ 45
$ 45
($ 100 credit)
$ 85 or $30,000/yr.
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deep well can save millions of dollars. Brine well salt producers have
traditionally deepwelled their wastes. Any other disposal method would
raise the disposal costs significantly and perhaps qlose down some
plants. An economically feasible method for disposal of wastes from the
Solvay soda ash plants is deep-welling. Unfortunately, at- least some of
the plants are located where deep-welling is not geologically feasible.
Treatment and disposal situations and costs for eastern and western
United States differ widely. Water is scarce in most of the west and,
therefore, is worth more for recovery and reuse. Pure water may be
worth 5.3* to 13.22/cu m (20
-------
SECTION IX
EFFLUENT REDUCTION ATTAINABLE THROUGH THE APPLICATION
OF THE BEST PRACTICABLE CONTROL TECHNOLOGY
CURRENTLY AVAILABLE,
The effluent limitations which must be achieved by July 1, 1977 are
based on the deqree of effluent reduction attainable through the
application of the best practicable control technology currently
available. For the inorganic chemical industry, this level of
technology was based on the best existing performance by exemplary
plants of various sizes, ages and chemical processes within each of the
industry's categories. In Section IV, the inorganic chemicals industry
was divided into three major categories based on the characteristics of
the The twenty-five inorganic chemicals investigated were grouped into
these three categories.
Best practicable control technology currently available emphasizes
treatment facilities at the end of a manufacturing process but also
includes the control technology within the process itself when it is
considered to be normal practice within an industry. Examples of waste
management techniques which were considered normal practice within the
inorganic chemicals industry are:
manufacturing process controls
cycle and alternative uses of water
recovery and/or reuse of wastewater constituents.
Consideration was also given to:
a. The total cost of application of technology in relation to the
effluent reduction benefits to be achieved from such application;
b. The size and age of equipment and facilities involved;
c. The process employed;
d. The engineering aspects of the application of various types of
control techniques;
e. Process changes;
f. Non-water quality environmental impact (including energy
requirements).
The following is a discussion of the best practicable currently
available treatment, methods for each of the chemicals in these
categories, and the proposed limitations on the parameters in their
effluents.
EFFLUENT REDUCTION ATTAINABLE USING BEST PRACTICABLE TECHNOLOGY CURRENTLY
AVAILABLE
Based upon the information contained in Sections III through VIII of
this report, the following determinations were made on the degree of
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effluent reduction attainable with the application of the best
practicable control technology currently available in the various
categories of the inorganic chemicals industry.
General Water Guidelines
Process water is defined as any water contacting the reactants of a
process including contact cooling water. All values of guidelines and
limitations presented below for total suspended solids (TSS), metals and
other pollutants are expressed as in units of pounds of parameter per
ton arid kg of parameter/kkg of product produced. The daily maximum
limitation is double the monthly average, except as noted. Unless
otherwise specified all process water effluents are limited to the pfi
range of 6.0 to 9.0.
In the chemical industry, at present, cooling and process waters are
mixed in some cases prior to treatment and discharge. In other
situations, only cooling water is discharged* Based on the application
of best practicable technology currently available, the recommendations
for the discharge of such cooling water are as follows:
(a) An allowed discharge of all non-contact cooling waters provided that
the following conditions are met:
(1) No potentially harmful pollutants are added. Cooling waters dis-
charged must not have levels of chromate, algicides, fungicides or
other pollutants which may be harmful higher than that of the intake
water or receiving water whichever is lower.
(2) Thermal pollution be in accordance with standards to be set by EPA
policies. Excessive thermal rise in oncethrc-ugh non-contact cooling
water in the inorganic chemical industry has not been a significant
problem.
(3) All non-contact cooling waters should be monitored to detect leaks
from the process and provisions should be made for emergency treatment
prior to release.
(4) No untreated process waters be added to the cooling waters prior
to discharge.
(b) An allowed discharge of water treatment, cooling tower and boiler
blowdowns provided these do not contain concentrations of pollutants
such as chromium or cadmium which may be harmful and are within the
required pR range.
Category 1 Chemicals
Aluminum chloride, aluminum sulfate (alum), calcium carbide,
hydrochloric acid, hydrofluoric acid, calcium oxide (lime), nitric acid,
potassium dichromate, potassium metal, potassium sulfate, sodium
bicarbonate, sodium chloride (Solar), sodium silicate and sulfuric acid
were placed in this category. Category 1 chemical planrs, utilizing the
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best existing treatment technologies, have a no discharge of process
waste water pollutants to navigable waters.
Aluminum Chloride
The process used for the manufacture of anhydrous aluminum chloride uses
no water except in cases where a scrubber is employed to eliminate the
discharge to the atmosphere of unreacted chlorine gas. There are
essentially three different grades of anhydrous aluminum chloride
product made using the process of reacting chlorine gas with molten
aluminum. The grey product is aluminum-rich; the white product is made
from stoichiometric quantities of aluminum and chlorine; and the yellow
producr is chlorine-rich. The grey and white product manufacture has
little or no chlorine evolving from the reactor and, therefore, dry
collection methods can be employed to minimize process dust. The
manufacture of yellow product requires wet scrubbing to trap the excess
chlorine gas as well as the process dust.
The exemplary aluminum chloride plant 125 uses a wet scrubber to produce
a 28 percent aluminum chloride solution as a product for sale and has no
water discharge. In cases where wet scrubbing is required and a market
for aluminum chloride solutions does not exist, these plants could treat
their scrubber effluent to precipitate the aluminum salts from solution
and recycle the supernatant liquid to the scrubber. Since the volume of
water used for scrubbing per day in plant 125 is only 2720 liters (720
gallons), another treatment approach could consist of concentrating the
scrubbing water containing aluminum chloride by recycling and then
evaporating to dryness to recover additional product.
The effluent limitations guidelines for aluminum chloride plants based
on best practicable technology currently available require no discharge
of process waste water pollutants to navigable waters.
Aluminum Sulfate
Aluminum sulfate is made by digesting bauxite ore in sulfuric acid. The
wastes emanating from this process consist of insolubles such as iron
and silicon oxides present in the bauxite. These wastes are removed
during settling and filtration of the product alum solution and also
during washdown of tanks. In both exemplary plants (049 and 063), the
waste muds are ponded to settle the solids and the clear water is
recycled to the process. No process water is discharged.
The effluent limitations guidelines for aluminum sulfate plants based on
best practicable technology currently available require no discharge of
process waste water pollutants to navigable waters.
No discharge of process wast water pollutants to navigaole waters is
also recommended for plants producing iron-free alum when refining of
the bauxite ore is not done on the plant site. The production of iron-
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free alum requires pure raw metals; that is, iron-free sulfuric acid and
iron-free hydrated alumina. The refining of the bauxite to produce the
iron-free hydrated alumina yields wastes that must be segregated from
the alum production process waters. The refining of bauxite to alumina
is not included in this phase of effort and, therefore, no effluent
guidelines for this process are presented in this report.
Calcium Carbide
The data cited from exemplary plant 190 shows that the only
manufacturing wastes involved are dusts emerging in tail gases from the
furnaces. These are collected by dry bag filtration methods and are
reused in the process or disposed of as solid wastes by landfilling.
The only water-borne effluent leaving plant 190 is cooling tower
blowdown water amounting to about 13.211 cu m/day (3500 GPD) which
contains some added water treatment chemicals. Presently, 80-90 percent
of the cooling water used at this plant is recycled. Dry bag collection
of solid waste and complete recycle of cooling water, or the use of
once-through non-contact cooling water, constitute the best practicable
control technology currently available.
The effluent limitations guidelines for calcium carbide plants based on
best practicable technology cureently available require no discahrge of
process waste water pollutants to navigable waters. Hydrochloric Acid
As indicated in Section III of this report, the manufacture of
hydrochloric acid by the chlorine burning process comprises a minor part
of the total U.S. production. All of the chlorine burning facilities
are located within chlor-alkali complexes. Exemplary plant 121 is one
such facility. The only waste generated from this process consists of
weak hydrochloric acid, and it is generated only during startup of the
operation. No waste emanates from the process during normal operation.
The startup weak acid waste is normally neutralized with sodium
hydroxide which yields a dissolved solids (sodium chloride) waste
amounting to about 0.5 kg/kkg (1 Ib/ton) of product acid. The weak
brine startup waste from the hydrochloric acid plant may be utilized in
the brine make-up operation at the chlor-alkali portion of the complex.
The effluent limitations guidelines for hydrochloric acid plants based
on best practicable technology currently available require no discharge
of process waste water pollutants to navigable waters.
Hydrofluoric Acid
The manufacture of hydrofluoric acid at exemplary plant 152 by the
reaction of fluospar (about 97% calcium fluoride) with sulfuric acid
generates about 3.1-3.6 kkg (3.5 to 4.0 tons) of solid waste per kkg of
product acid. All wastes from the process are water slurried to
settling ponds, and the clear liquid is recycled for the same purpose.
All process water is segregated frcm. non-contact cooling water. Also,
356
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the process is conducted at a reduced pressure so that if a leak occurs,
the cooling water enters the system and the product is contaminated and
not the discharged cooling water.
The effluent limitations guidelines for hydrofluoric acid plants based
on best practicable technology currently available require no discharge
of process waste water pollutants to navigable waters.
Calcium Oxide and Calcium Hydroxide (Lime)
The manufacture of lime by the calcination of limestone is a dry process
and uses only non-contact cooling water, and, in some cases, contact
scrubber water. Exemplary plant 007 uses dry bag dust collectors and,
therefore, discharges no process water. The use of dry bag collection
methods is not contingent on the use of specific fuels for the
calcination kilns nor is it geographically dependent and constitutes the
best practicable treatment technology currently available to eliminate
water wastes and minimize air pollution from calcium oxide plants.
The effluent limitations guidelines for lime plants based on best
practicable technology currently available require no discharge of
process waste water pollutants to navigable waters.
Nitric Acid
Commercial grade nitric acid (up to 70% concentration) is made by the
oxidation of ammonia and, at exemplary plant 114, all process waters are
recycled with no discharge. Of the 30,280 cu.m (8 million gal) of water
per day used for cooling, about 95% is recycled. An additional 757 cu.m
(0.2 million gal) of water per day are used to make steam for the pro-
cess, and 75% of this quantity is recycled. About 87 cu.m (23,000 gal)
per day of steam condensate is used for acid make-up water. The
discharge from the plant consists of noncontact cooling water which
contains blowdowns from boilers, cooling towers and water treatment with
a total non-toxic waste load amounting to about 2 kg/kkg (4 Ib/ton) of
product produced. The best practicable treatment technology available
for commercial grade nitric acid plants is the recycle of all process
waters and the segregation of process waters from cooling water.
Extensive amounts of suspended solids generated from water treatment can
be controlled by settling ponds.
The effluent limitations guidelines for plants producing nitric aced up
to 70? concentration based on best practicable technology currently
available require no discharge of process waste water pollutants to
navigable waters.
Potassium Bichromate
The process for the production of potassium dichromate involves the
reaction of potassium chloride with sodium dichromate. At exemplary
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plant 002, all process water is recycled and sodium chloride (UOO kg/kkq
of product) is removedc as a solid waste. The only water-borne waste
source is contamination of cooling water by hexavalent chromium in a
barometric condenser presently in use on the product crystallizer. The
plant has plans to replace the barometric condenser with a non-contact
type heat exchanger which will eliminate cooling water contamination.
The effluent limitations guidelines for potassium dichromate plants
based on best practicable technology currently available require no
discharge of rpocess waste water pollutants to navigable waters.
Potassium Metal
Exemplary plant OU5 produces most of the potassium metal manufactured in
the U.S. by a completely dry process. No water is used, not even for
cooling purposes. Therefore, The effluent limitations guidelines for
plants based on best practicable technology currently available require
no discharge of process waste water pollutants to navigable waters.
Potassium Sulfate
All of the potassium sulfate manufacturers in the U.S. are located in
the arid southwest close to deposits of langbeinite ore (K2S04.2MgSOt») .
The reaction of this ore with a potassium chloride solution and the
subsequent crystallization and separation of potassium sulfate from
magnesium chloride brine constitutes the process for the production of
potassium sulfate. A large amount (about 2000 kg/kkg of product) of
magnesium chloride brine is a co-product of this process. Exemplary
plant 118 sells most of this brine when the sodium content of the ore is
low and ponds the brine for evaporation when it can't be sold.
Evaporation ponds in this area of the country are no problem. The cost
of water is a problem and most of the liquor in the brine is recycled
back to the process for reuse before the magnesium chloride is sold or
dumped. The percolation of the dumped soluble chloride and
contamination of ground water apparently has not been a problem to date.
Other insoluble wastes from the process muds amount to about 15 kg/kkg
of product, and they are landfilled. Because of the geographical
dependence of plants manufacturing potassium sulfate to the arid
southwest evaporation ponds are feasible. The effluent limitations
guidelines for plants based on best practicable technology currently
available require no discharge of process waste water pollutants to
navigable waters.
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Sodium Bicarbonate
Sodium bicarbonate is manufactured by the carbonation of a sodium
carbonate (soda ash) solution. Most plants are located in or n«^ar
complexes manufacturing soda ash by the Solvay Process. There is onr
isolated facility which uses mined soda ash as a raw mat-rial.
Exemplary sodium bicarbonate plant 166 is located within a Solvay
Process complex. The major wastes from this process are about 10 of un-
dissolved sodium bicarbonate per kkg of product and an average of about
38 of dissolved sodium bicarbonate per ton of product. Some of the
undissolved sodium bicarbonate is reusable and it is redissolved and
recycled to the process. The remainder is landfilled along with sand
from the filters and other non-process type solid waste. The present
discharge of approximately 76 cu.m per day (20,000 GPD) contains an
average of 20,000 mg/1 of dissolved solids and little or no suspended
solids which are removed in a settling pond. Plant 166 has plans to use
the weak slurry thickener overflow, which constitutes their presen-t-
major source of waste, as a source of liquid for trie product dryer
scrubber and recycle this liquid to concentrate it with respect, to
sodium carbonate and reuse it in the process. These process change
will eliminate the discharge of process waste waters.
The effluent limitations guidelines for sodium bicarbonate plants based
on best practicable technology currently available require no discharg-
of process waste water pollutants to navigable waters.
Sodium Chloride (Solar)
Solar salt is produced by the long-term solar evaporation of sea water
to precipitate sodium chloride. This process generates a bittern waste
solution consisting mainly of sodium, potassium and magnesium salts.
Many solar salt plants in the U.S. are located in California, and this
state prohibits the discharge of bitterns to the ocean. Exemplary plant
059 reclaims some of the waste salts from the bitterns and stores the
rest for future reclamation. The process is highly geographically
dependent. There is no discharge of process waste water from plant 059.
The effluent limitations guidelines for solar process sodium chloride
plants based on best practicable technology currently available require
no discharge of process waste water pollutants to navigable waters.
Sodium Silicate
Sodium silicate is produced by the reaction of soda asii aria silica in a
furnace to form a sodium silicate glass. The material is sold either as
a solid glass product or is pressure dissolved in water and sold as a
solution with various ratios of silica to sodium oxide. The water-borne
waste generated consists of unreacted silica, sodium hydroxide and
sodium silicate from tank washdowns, product shock cooling with water
and scrubber effluent. At exemplary plant 072, these wastes are ponded
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•to settle the solids and the clear liquid is partially recycled and
partially pond evaporated, resulting in no discharge of process waste
water.
The effluent limitations guidelines for sodium silicate plants based on
best practicable technology currently available require no discharge of
process waste water pollutants to navigable waters.
Sulfuric Acid
Sulfuric acid is manufactured using the sulfur-burning Contact Process
by three different types of plants. These are single absorption plants,
double absorption plants and spent acids plants. The guidelines
presented herein do not apply to spent acid plants.
Exemplary plant 1U1 is a single absorption plant and exemplary plant 086
is a double absorption plant. The double absorption plant has no
process waste and uses only non-contact cooling water. The single
absorption plant requires the use of wet scrubbing to minimize air
pollution, and the scrubber water is recycled. This plant also uses
non-contact cooling water. The only process waste from these plants
emanates from the cooling system if leaks occur contaminating the
cooling water. These leaks should be controlled in accordance with
paragraph 2.1 of this section of the report. There is no discharge of
process waste water from these exemplary plants.
The effluent limitations guidelines for single and double absorption
sulfur burining sulfuric acid plants based on best practicable
technology currently available require no discharge or process waste
water pollutants to navigable waters. The Level I guidelines and
limitations recommended for single and double absorption sulfur burning
sulfuric acid plants are zero discharge of pollutants in process waste
waters.
Category 2 Chemicals
Calcium chloride, hydrogen peroxide (organic), sodium carbonate (soda
ash), sodium chloride (brine mining), sodium metal and sodium sulfite
were placed in this category. Category 2 chemical plants, utilizing the
best existing treatment technologies, have process effluents containing
suspended solids with no harmful metals present.
Calcium Chloride
Calcium chloride is produced by extraction from natural brine and as a
by-product of soda ash manufacture by the Solvay Process. The
guidelines presented herein apply only to the brine extraction process.
The process wastes are weak brine solutions, and they emanate from the
blowdown of various brine purification steps and from several
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evaporation steps used in the process. The currently available
practicable treatment technology used at exemplary plant 185 is to pass
the waste brine streams through activated sludge to remove organics,
pond to settle suspended solids and adjust pH and final pond to remove
additional suspended solids before discharge. The process water
discharge flow amounts to an average of 330 1/kkg of product ("79
aal/ton), and contains suspended solids but no harmful metals or other
pollutants. The recommendations are based on this performance.
The following limitations constitute the quantity or quality of
pollutants or pollutant properties which may be discharged after
application of the best practicable control technology currently
available by calcium chloride plants using the brine extraction process:
TSS 0.0082 kg/kkg (0.0164 Ib/ton)
Harmful metals 0
and pollutants
Hydrogen Peroxide (Organic)
The organic process for the manufacture of hydrogen peroxide at
exemplary plant 069 generates a .waste stream containing 0.17-0.35 kg/kkg
(0.34-0.70 Ibs/ton) of organics. The treatment methods currently used at
this plant include an 80% reduction of hydrogen peroxide to water and
oxygen, a recovery system which recovers 60-70 percent of lost organics,
and tank diking and process curbing to retain waste spills. The process
water use in this facility is 16,000 1/kkg of product (3,800 gal/ton)
and contains, after treatment, suspended solids and organic matter, but
no harmful metals. The recommendations are based on this performance.
The following limitations constitute the quanitity or quality of
pollutants or pollutant properties which may be discharged after
application of the best practicable control technology currently
available by The Level I guidelines and limitations recommended for
process organic process hydrogen peroxid plants:
TSS O.UO kg/kkg (0.80 Ib/ton)
Harmful metals 0
and pollutants
TOC 0.22 kg/kkg (0.44 Ib/ton)
Sodium Carbonate (Soda Ash - Solvay)
The Solvay Process for the manufacture of sodium carbonate (soda ash)
involves the reaction of sodium chloride brine, ammonia and carbon
dioxide to yield crude soda ash. The ammonia is recovered from the
process by reacting the spent brine solution with lime followed by
distillation. This process produces about 1500 of dissolved solids
waste per kkg of soda ash manufactured. Calcium chloride comprises the
majority of this waste, amounting to about 1050 for every kkg of soda
ash. There are no truly exemplary plants manufacturing soda ash by the
Solvay Process but plant 166 recovers about 21 percent of the waste
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calcium chloride for sale. The total recovery of calcium chloride is
not practical because of the limited market value. The only treatment
used at this plat is a settling pond to reduce the concentration of
suspended solids in the effluent. Therefore the Level I guideline
recommendations are not based on by-product recovery, but upon the water
flow necessary to maintain the total calcium chloride by-product formed
in the process at a 10% concentration at discharge (6,900 1/kkg of soda
ash (1,650 qaI/ton). Suspended solids but no harmful metals or other
pollutants should also be present. The following limitations constitute
the quantity or quality of pollutants or pollutant properties which may
be discharged after application of the best practicable control
technology currently available;
TSS 0.17 kg/kkg (0.34 Ib/ton)
Harmful metals
and pollutants 0
Sodium Chloride (Brine Mining)
Sodium chloride manufacture by this process involves pumping of water
into an underground salt deposit (solution mining) and returning brine
for treatment to remove impurities and then to multiple effect
evaporators to crystallize and collect the pure sodium chloride for
sale. At exemplary plant 030, the brine sludges from the brine
purification step are disposed of by returning them to the mine. Other
sources of waste water are the purges from the evaporators, spills and
the barometric condenser. All of the concentrated brine wastes are
recycled to the process. The current plant effluent is neutral in pH
and low in suspended solids.
The following limitations constitute the quantity or quality of
pollutants or pollutant properties which may be discharged after
application of the best practicable control technology currently
available by solution mining evaporative process sodium chloride plants
are:
TSS 0.15 kg/kkg (0.30 Ib/ton)
Harmful metals 0
and pollutants
Sodium Metal
The process for the manufacture of sodium metal, commonly called the
Downs Cell Process, is essentially dry. However, water-borne wastes are
generated during cleanout and washdown of cells when the electrolyte is
replenished, from scrubbing chlorine tail gases and from drying the
chlorine with sulfuric acid. At exemplary plant 096, the spent drying
acid is not discharged but used elsewhere in the works complex. The
wastes from cell wash-downs, runoff water and residual chlorine-
containing water from the tail gas scrubber are ponded to settle
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suspended solids and then discharged. At plants where the utilization
of the spent drying acid and calcium hypochlorite solution is not
possible, it is recommended that the spent acid be sold to a "decomp"
sulfuric acid plant and the calcium hypochlorite solution be recovered
and marketed as a bleach product. The recommendations are based on the
discharge volume of process water other than barometric condensers and
should contain suspended and dissolved solids but no harmful metals or
other pollutants.
The following limitations constitute the quantity or quality of
pollutants or pollutant properties which may be discharged after
application of the best practicable control technology currently
available by sodium metal manufacture plants:
TSS 0.23 kg/kkg (O.U6 Ib/ton)
Harmful metals 0
and pollutants
Sodium Sulfite
Sodium sulfite is manufactured by the reaction of sulfur dioxide with
soda ash. The process wastes are mainly sulfides from product
purification and sodium sulfite/sodium sulfate solutions from the
product dryer ejector, filter washings and vessel cleanouts. Exemplary
plant 168 is the only sodium sulfite plant currently treating the waste
sulfite-containing solutions to oxidize sulfite to sulfate. The
efficiency of this aeration treatment is about 94 percent. An
additional filtration treatment is given to the process waste water
which removes 98 percent of the suspended solids. The recommendations
are based on the waste stream flow emanating from the dryer ejector and
filter wash operations of this plant at the high end of its range (630
liters per kkg or 150 gal/ton) and contains dissolved and suspended
solids and sulfite ion, but no harmful metals or other pollutants.
The following limitations constitute the quantity or quality of
pollutants or pollutant properties which may be discharged after
application of the best practicable control technology currently
available by sodium sulfite plants:
TSS 0.016 kg/kkg (0.032 Ib/ton)
Harmful metals 0
and pollutants
COD 1.7 kg of dichromate ion/kkg
Category 3 Chemicals
Chlorine-alkali (diaphragm cell), chlorine-alkali (mercury cell),
hydrogen peroxide (electrolytic), sodium dichromate, sodium sulfate,
titanium dioxide (chloride process) and titanium dioxide (sulfate
process) were placed in this category. Category 3 chemical plants,
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utilizing the best existing trea##ent technologies, have process
effluents containing suspended solids with harmful metals present.
Chlorine-Alkali (Diaphragm Cell)
The diaphragm cell process for the manufacture of chlorine and caustic
soda or caustic potash usually have the following raw wastes emanating
from the process:
a. a solution of sodium hypochlorite and sodium bicarbonate from the
scrubbing of chlorine tail gases (about 7.5 kg of dissolved solids/kkg
of chlorine produced)
b. chlorinated organics from the liquifaction of chlorine gas (about
0.7 kg/kkg of chlorine produced)
c. brine wastes from the brine purification system (about 12.2 kg of
dissolved solids /kkg of chlorine produced)
3. spent sulfuric acid from the chlorine drying process (about 4,2
kg/kkg of chlorine produced)
e. weak caustic and brine solution frcm the caustic evaporators using
barometric condensers (about 9.5 kg of dissolved solids/kkg of
chlorine produced)
f. weak caustic and brine solution from the caustic filter washdown
(about 37.5/kg of dissolved solids/ kkg of chlorine produced).
At exemplary plant 157, the tail gas scrubber wastes are presently
discharged, but the plant intends to install a chlorine burning
hydrochloric acid plant in the near future which will eliminate the
scrubber wastes. This, however, constitutes the best practicable
technology currently available. The chlorinated organics are disposed
of by incineration. The brine wastes from brine purification are ponded
to settle out suspended solids and the brine liguor is recycled to brine
make-up. The spent sulfuric acid at this plant is utilized elsewhere in
the complex or sent back to a spent sulfuric acid plant for
regeneration. Some plants presently use this acid to partially
neutralize caustic wastes in the plant which aides in controlling the
effluent pH but adds to the total dissolved solids present. The weak
caustic/brine solution from the caustic evaporators can be eliminated by
replacing the barometric condensers with non-contact surface condensers
or by recycling the discharge from the barometric condenser back to
brine make-up. The weak caustic/brine solution from the caustic filters
is presently pH adjusted and discharged.
The following limitations constitute the quantity or quality of
pollutants or pollutant properties which may be discharged after
application of the best practicable control technology currently
available by diaphragm cell chlor-alkali plants
TSS 0.083 kg/kkg (0.17 Ib/ton)
Harmful metals 0.0025 kg/kkg (0.005 Ib/ton) lead
and pollutants
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Chlorine-Alkali (Mercury Cell)
The mercury cell process for the manufacture of chlorine and caustic
soda or caustic potash usually has similar wastes to the diaphragm cell
process which was discussed in paragraph 2.4.1 of this section. The
ma-jor exception is the loss of mercury from the process. Exemplary
plants 144, 098 and 130 have excellent mercury control systems to
minimize the incorporation of mercury into discharge streams. These
controls consist of curbing the cell area to retain mercury lost in
spills or leaks, collecting all mercury before ponding arid dischargc-
and/or recycling mercury-containing waste water back to the cells for
reuse after treatment to remove any impurities. These plants have
continuous mercury monitors or. streams possibly contaminated tnat are
meant for ponding to settle suspended solids before discharge. The
mercury recommendation is based on the discharge performance achieved by
the three plants studied, whose discharges per ton of chlorine are very
similar.
The following limitations constitute the quantity or quality of
pollutants or pollutant properties which may be discharged -ifn-r
apnlication of the best practicable control technology currently
available by
TSS 0.32 kg/kkg (0.65 Ib/ton) of chlorine
Harmful 0.00007 kg/kkg (0.00014 Ib/ton) mercury
metals and
pollutants
Hydrogen Peroxide (Electrolytic)
There is only one plant in the U.S. that makes hydrogen peroxide by the
electrolytic process. Plant 100 recovers all of the solids present in
the process wastes and ion exchange treats to recover 98 percent of the
cyanides present in the waste stream before discharge. The current
process water discharge is low in suspended solids and marginally low to
medium in dissolved solids. The ion exchange regenerant is pH
controlled prior to discharge.
The following limitations constitute the quantity or quality of
oollutants or pollutant properties which may be discharged after
application of the best practicable control technology currently
available by electrolytic process hydrogen peroxide plant are based on
the exemplary plants:
TSS 0.0025 kg/kkg (0.005 Ib/ton)
Harmful 0.0002 kg/kkg (0.0004 Ib/ton) cyanide ion metals and
pollutants
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Sodium Dichromate and Sodium Sulfate
These two chemicals are manufactured as co-products by the calcination
of a mixture of chrome ore, soda ash and lime followed by water leaching
and acidification of the soluble chromates. The sodium sulfate product
is crystallized out after acidification. The bulk of the wasre
originates from the undigested portions of the ore and is mostly solid
wastes. Water-borne wastes arising from spills and washdowns contain
most of the hexavalent chromium. Plant 184 was chosen as exemplary
because of its excellent treatment to minimize the discharge of
hexavalent chromium. The treatment consists of good containment of
spills, leaks and rain water runoff in chromate areas of the plant
followed by treating the chromium-containing wastewater with Dickie
liquor to affect reduction of the chromates and then lagooning to settle
out suspended solids before discharge. This treatment removes 99
percent of the hexavalent chromium. However, the pickle liquor
treatment for removal of hexavalent chromium generates large amounts of
solid and dissolved solids waste and is not recommended unless
acceptable provisions are available for proper treatment and/or disposal
of the wastes. Dichromate plant 014 uses the more conventional sodium
hydrosulfide treatment to reduce the hexavalent chromium and subsequent
lime treatment limits the discharge to the solubility limits of calcium
sulfate (2000 mg/1) and about 0.1 mg/1 of unreacted hexavalent chromium
and a total dissolved chromium level of 0.5 mg/1.
The Level I guidelines and limitations recommended for prosodium
dichromate sodium sulfate co-product plants: The following limitations
constitute the quantity of quality of pollutants or pollutant properties
which may be discharged after application of the best practicable
control technology currently available by
TSS 0.22 kg/kkg (0.44 Ib/ton)
Harmful metals 0.0009 kg/kkg (0.0018 Ib/ton)
and pollutants hexavalent chromium
0.0044 kg/kkg (0.0088 Ib/ton)
total chromium
Titanium Dioxide (Chloride Process)
The amount of wastes generated by the manufacture of titanium dioxide by
either the chloride or sulfate process is heavily dependent on the
purity of raw material used. The exemplary chloride process plant 009
uses neutralization, clarification and ponding to settle suspended
solids and to precipitate harmful metals, as treatment methods. The
relatively large amounts of suspended and dissolved solids, expressed as
kg per kkg or as pounds per ton of product titania, are due mainly to
the relative impurity of the ores used in the process. About 93 percent
of the cooling water is recycled but there appears to be no practical
approach for recycling process water. Deep well disposal is utilized by
another company (plant 160). The plant effluent is neutral pH and
contains mostly sodium chloride as the dissolved solid.
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The following limitations constitute the quantity or quality of
pollutants or pollutant properties which may be discharged after
apolication of the best practicable control technology currently
availablble by
TSS 2.2 ka/kkg (U.4 Ibs/ton)
Harmful metals 0.036 kg/kkg (0.072 Ib/ton) iron
and pollutants 0.014 kg/kkg (0.028 Ib/tor.) lead
0.015 kg/kkg (0.030 Ib/ton) total
other metals includira vanadium,
aluminum, silicon, chromium,
magnesium, niobium and zirconium
Titanium Dioxide (Sulfate Process)
Of the five sulfate process titanium dioxide plants in the U.S., nonr- is
considered exemplary. The high iron content in the ilmenite ore raw
material is a major source of the wastes generated by this process.
Another major contributor to the process waste is the large amount of
spent sulfuric acid from digestion of the ore. Very little treatment is
presently being used and the effluents from these plants are highly
acidic and contain high concentrations of suspended and dissolved solids
including harmful metal ions. ocean barging is used by some to dispose
of the process waste waters. Plant 122 is presently installing
treatment facilities to neutralize and oxidize the process waste to
remove acid as calcium sulfate, to reduce the chemical oxygen demand and
reduce the concentration of harmful metal ions. They also plan
additional settling ponds to reduce the suspended solids formed during
••-he neutralization treatment. Considerable research is being done to
improve treatment technologies for this process and this is discussed in
Section VII of this report.
The following limitations constitute the quantity or quality of
pollutants or pollutant properties which may be discharged after
application of the best practicable control technology currently
available by sulfate process titanium dioxide plants:
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TSS 2.5 kg/kkg (5.0 Ibs/ton)
Harmful metals Iron - 0.1 kg/kkg ( 0.2 Ib/ton)
and pollutants maximum as FeO
Vanadium - 3.2 kg/kkg (6.4 Ibs/ton)
average as V2O5
Aluminum - 0.1 kg/kkg (0.2 Ib/ton)
maximum as A12O3
Silicon - 0.1 kg/kkg (0.2 Ib/ton)
maximum as SiO2
Manganese - 2.0 kg/kkg (U.O Ibs/ton)
maximum as MnO
Cobalt - 0.1 kg/kkg (0.2 Ib/ton)
maximum as CoO
Chromium - 0.1 kg/kkg (0.2 Ib/ton)
maximum as Cr2O3
The above guidelines are based on a modeled sulfate process titanium
dioxide plant using 100,000 of process water per kkg of product, and
allowing 25 mg/1 of suspended solids in the effluent. The dissolved
metal limitations are based on solubility limits of the oxides in a
neutral pH effluent. An average of the concentrations of m~tal
impurities in Adirondack and Australian Ilmenite ores was used to
establish the levels.
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SECTION X
EFFLUENT REDUCTION ATTAINABLE THROUGH THE
APPLICATION OF THE BEST AVAILABLE
TECHNOLOGY ECONOMICALLY ACHIEVABLE,
The effluent limitations which must be achieved by July i, 1983 are
based on the degree of effluent reduction attainable through the
application of the best available technology economically achit=v.ribl-.
For the inorganic chemical industry, this level of technology was b^ot-d
on the very best control and treatment technology employed by a specific
point: source within the industrial category or subcategory, or where it
is readily transferable from one industry process to another. in
Section IV, the inorganic chemicals industry was divided into three
major categories based on the characteristics in the effluents emerging
from the various facilities under study. The twenty-five inorganic
chemicals investigated were grouped into these three categories.
The following factors were taken into consideration in determining tr,~
best available -^echnology economically achievable:
a. the age of equipment and facilities involved;
b. the process employed;
c. the engineering aspects of the application of various types of
control techniques;
d. proc-ss changes;
e. cost of achieving the effluent reduction resulting from
application of Level II technology; and
f . non-water quality environmental impact (including energy
requirements).
In contrast to the best practicable technology currently available, best
available technology economically achievable assesses the availability
in all cases of in-process controls as well as control or additional
treatment techniques employed at the end of a production process. In-
nrocess control options available which were considered in establishing
these control and treatment technologies include the following:
a. alternative water uses
b. water conservation
c. waste stream segregation
d. water reuse
e. cascading water uses
f. by-product recovery
g. reuse of wastewater constituent
h. waste treatment
i. good housekeeping
j. preventive maintenance
k. quality control (raw material, product, effluent)
1. monitoring and alarm systems.
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Those plant processes and control technologies which at the pilot plant,
semi-works, or other level, have demonstrated both technological
performances and economic viability at a level sufficient to reasonably
-justify investing in such facilities were also considered in assessing
Level II techthe best available technology economically achievable. Ir
is the highest degree of control technology that has been achieved and
has been demonstrated to be capable of being designed for plant: scale
operation up to and including "no discharge" of pollutants. Although
economic factors are considered in this development, tne costs for this
level of control are intended to be for the top-of-t.heline of current
technology subject to limitations imposed by economic and engineering
feasibility. However, this technology may necessitate some industrially
sponsored development work prior to its application.
EFFLUENT REDUCTION ATTAINABLE USING BEST AVAILABLE TECHNOLOGY
ECONOMICALLY ACHIEVABLE
Based upon the information contained in Sections III through IX of this
report, the following determinations were made on the degree of effluent
reduction attainable with the application of the best available control
technology economically achievable in the various categories of the
inorganic chemical industry.
General Water Guidelines
Process water is defined as any water contacting the reactants of a
process including contact cooling water. All values of guidelines and
limitations presented below for total suspended solids (TSS) and harmful
metals and pollutants are expressed as 30-day averages in units of kg of
parameter per metric ton (Ibs/ton) of product produced. The daily
maximum limitation is double the monthly average, except as noted.
Where zeros appear for a parameter the zero means no increase above that
of the intake or receiving water, whichever is lower.
Unless otherwise specified all process water effluents are limited to
the pH range of 6.0 to 9.0. Exceptions to this range must be considered
on an individual case basis.
The recommendations for noncontact cooling waters and blowdowns are the
same as those based on best practicable technology currently available
except that monitoring shall be required for process leaks and
provisions shall be made for emergency holding facilities for cooling
water contaminated by leaks until such time as they can be treated.
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Category I Chemicals
All Category i chimiccil plants were required to achieve no discnarge of
process waste water pollutants to navigable waters based on best
available technology currently available. The same limitations
guidelines are required based on best available technology economically
ahcievable.
Category 2 Chemicals
The chemicals in this category are calcium chloride, hydrogen peroxide
(organic), sodium carbonate (soda ash), sodium chloride (brine mining),
sodium metal and sodium sulfite.
Calcium Chloride
Exemplary plant 185 has plans to reduce their evaporator and recycle the
packaging area washdown, which will eliminate the discharge of calcium
chloride and ammonia. Therefore, the effluent limitations guidelines
for calcium chloride based on the application of the best available
technology economically achievable require no discharge of process waste
water pollutants to navigable waters.
Hydrogen Peroxide (Organic)
Best available technology for organic process hydrogen peroxide plants
is to recycle all process water. The discharged process water presently
contains hydrogen peroxide and organic solvent which should not be
detrimental to the process. The effluent limitations guidelines for
hydrogen peroxide (organic) based on the application of the best
available technology economically achievable require no discharge of
process waste water pollutants to navigable waters.
Sodium Carbonate (Soda Ash - Solvay)
The calcium chloride raw waste load of the Solvay process is such that
10 to 15 percent of it can supply the total volume of the U.S. market
for calcium chloride, so the potential for waste disposal through this
channel is limited. Large capital costs are involved to bring Solvay
process plants to the capability of zero discharge, and the disposal of
the unmarketable by-product calcium chloride is difficult due to its
extreme solubility. However, technology does exist to further reduce
the concentration of suspended solids to 15 mg/1. The following
limitations constitute the quantity of pollutants which may be
discharged after the application of best available technology
economically achievable for soda ash produced by the lines and
limitations recommended for soda ash produced by the Solvay process:
TSS 0.10 kg/kkg (0.20 Ib/ton)
Harmful metals 0
and pollutants
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Sodium Chloride
The major source of the discharged sodium chloride dissolved solids
waste generated at plant 030 emanates from carryover in the barometric
condensers. The Level II technology recommended for brine mining
evaporative process sodium chloride plants is to replace the barometric
condensers with non-contact heat exchangers and recycle the steam
condensate to the evaporators. The effluent limitations guidelines for
evaporative process sodium chloride plants based on the application of
the best available technology economically* achievable require no
discharge of process waste water pollutants to navigable waters.
Sodium Metal
Best available technology for sodium metal-chlorine plants is:
a. Recycle of the wastes from cell washdowns to brine purification
after removal of suspended solids.
b. Recovery of the calcium hypochlorite waste from the tail gas
scrubber as a product and recycle of water to the scrubber, or replace
the scrubber with a chlorine-burning hydrochloric acid facility.
c. Recycle the spent sulfuric acid used for drying the chlorine to a
"decomp" sulfuric acid plant or sell to a possible user of weak acid.
The effluent limitations guidelines for sodium metal-chlorine plants
based on the application of the best available technology economically
achievable require no discharge of process waste water pollutants to
navigable waters.
Sodium Sulfite
Best available technology for sodium sulfite plants is recovery of the
sodium sulfate from the waste discharge by evaporation and sale as a by-
product. This should not be too costly since the volume of effluent
from exemplary plant 168 averages only 1U26.5 cu m per day (3700-7000
gallons per day), and the dissolved solids in this stream are mostly
sodium sulfate.
The effluent limitations guidelines for sodium sulfite plants based on
the application of the best available technology economically achievable
require no discharge of process waste water pollutants to navigable
waters.
Category 3 Chemicals
Chlor-alkali (diaphragm cell), chlor-alkali (mercury cell), hydrogen
peroxide (electrolytic), sodium dichromate, sodium sulfate, titanium
dioxide (chloride process) and titanium dioxide (sulfate process) are
included in this subcategory.
372
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Chlor-alkali (Diaphragm Cell)
Best practicable technology currently available for the manufacture of
chlorine/caustic soda or caustic potash by the diaphragm cell process
allows the discharge of treated wastes from the tail gas scrubber and of
neutralized spent acid from chlorine drying. Best available technology
is elimination of the pollutant discharge by:
a. Catalytic treatment of the hypochlorite waste from the scrubber to
convert to a brine and recycle to brine purification, recovery of the
hypochlorit- as a bleach product or elimination of the scrubber and
utilization of the chlorine gas elsewhere in the plant, such as in a
chlorine-turning hydrochloric acid plant;
b. Recovery of the spent acid from chlorine drying and sale,
utilization elsewhere in the plant or return to spent sulfuric acid
plant for regeneration; and
c. Recycle of all weak brine/caustic solutions to the process after
extraction/elimination of harmful metals and impurities.
The effluent limitations guidelines for diaphragm cell chlor-alkali
plants based on theapplication of the best available technology
economically achievable reguire no discharge of process waste water
pollutants to navigable waters.
Chlor-alkali (Mercury Cell)
See the preceding paragraph for the Level II technology recommended for
diaphragm cell plants. The same technology cited above for diaphragm
cell plants applies to mercury cell plants. The effluent limitations
guidelines for sodium sulfite plants based on the application of the
best available technolocry economically achievable require no discharge
of process waste water pollutants to navigable waters.
The effluent limitations guidelines for mercury cell chlor-alkali plants
based on the application of the best available technology economically
achievable reguire no discharge of process waste water pollutants to
navigable waters.
Hydrogen Peroxide (Electrolytic)
Pest available technology for this process is to segregate the process
wastewater from the cooling water discharge and treat the relatively
small amount of process wastewater by distillation and recycle the
distillate to the process. The solid wastes from the distillation could
be land-filled.
The effluent limitations guidelines for electrolytic process hydrogen
peroxide plants based on the application of the best available
technology economically achievable require no discharge of process waste
water pollutants to navigable waters.
373
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Sodium Dichromate and Sodium Sulfate
At exemplary plant 184, a total of approximately 113,000 kkg of product
and by-product are manufactured per year. The additional treatment cost
to this plant for the evaporation of the effluent to effect zero
discharge would amount to about $250,000 per year. This would mean an
approximate cost increase per kkg of sodium dichromate and sodium
sulfate of $2.20. The effluent limiations guidelines for sodium
dichromate and byproduct sodium sulfate plants, based on the application
of the best available technology economically achievable, require no
discharge of process waste water pollutants to navigable waters.
Titanium Doxide (Chloride and Sulfate Processes)
The best practicable technology currently available for these processes
were based on the intended near future treatments planned by the
titanium dioxide. As indicated in Section VIII of this report, the
additional treatment costs projected to bring each of these processes
down to zero discharge of process wastewater by demineralization and
evaporation of regenerant solutions are as follows:
ai_Chl,oriLde_2rocess - an additional $730,000 per year for a plant with
a 24,300 kkg (27,000 ton) per year capacity or an increase of
approximately 5% over the costs of best practicable technology.
bi_Sulfate_erocess - an additional $620,000 per year for a plant with
a 39,600 kkq (43,000 ton) per year capacity or an increase of
approximately 3% over the costs of best practicable technology
However, evaporation of the large amounts of water necessary in both
processes would create energy problems and also solid waste disposal
problems. The technology does exist to reduce the concentration of
suspended solids to 15 mg/1, the following limitations constitute the
quanity of pollutants which may be discharged after application of the
best available technology economically achievable by titanium dioxide.
a. Chloride Process:
TSS
Harmful metals
and pollutants
1.3»kg/kkg (2.6 Ibs/ton)
0.036 kg/kkg (0.072 Ib/ton) iron
0.014 kg/kkg (0.028 Ib/ton) lead
0.015 kg/kkg (0.030 Ib/ton) total other
metals including vanadium, aluminum,
silicon, rchromium, manganese, niobium
and zirconium
These guidelines based on exemplary plant
concentration of suspended solids to 15 mg/1.
009 further reducing the
b. Sulfate Process:
TSS
Harmful metals
and pollutants
1.5 kg/kkg (3.0 Ibs/ton)
Iron - 3.2 kg/kkg (6.4 Ibs/ton)
average as FeO
374
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Vanadium -
average as
Aluminum -
maximum as
Silicon - 0.
maximum as
Manganese
maximum
Cobalt -
maximum
Chromium
maximum
0.1 kg/kkg (0.2 Ib/ton)
V205
0.1 kg/kkg (0.2 Ib/ton)
A1203
1 kg/kkg (0.2 Ib/ton)
Si O2
- 2.0 kg/kkg (4.0 Ib/ton)
as MnO
0.1 kg/kkg (0.2 Ib/ton)
as CoO
- 0.1 kg/kkg (0.2 Ib/ton)
as Cr203
The above guidelines are based on a modeled sulfate process ri-.anim
dioxide plant using 100,000 of process water per kkg of product, and
allowing 15 mg/1 suspended solids in the effluent. The dissolved metal
limitations are based on solubility limits of the oxides in a neutral pH
effluent. An average of the concentrations of metal impurities in
Adirondack and Australian Ilmenite ores was used to establish the
levels.
375
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SECTION XI
NEW SOURCES PERFORMANCE STANDARDS
AND PRETREATMENT STANDARDS,
This level of technoloqy is to be achieved by new sources. The *-.--n\
"new source" is defined in the Act to mean "any source, the construe4:ion
of which is commenced after the publication of proposed regula-iorrs
prescribing a standard of performance". This technology is evaluated by
adding to the consideration underlying the identification of best
available technoloqy economically achievable, a determination of what
higher levels of pollution control are available through the use of
improved production processes and/or treatment techniques. Thus, in
addition to considering the best in-plant and end-of-process control
technoloqy, new source performance standards are how the level of efflu-
ent may be reduced by changing the production process itself.
Alternative processes, operating methods or other alternatives were
considered. However, the end result of the analysis identifies effluent.
standards which reflect levels of control achievable through the use of
improved production processes (as well as control technology), rather
than prescribing a particular type of process or technology which must
be employer!.
The following factors were considered with respect to production process
which were analyzed in assessing the best demonstrated control
technology currently available for new sources:
(a) the type of process employed and process changes;
(b) operating methods;
(c) batch as opposed to continuous operations;
(d) use of alternative raw materials and mixes of raw materials;
(e) use of dry rather than wet processes (including substitution of
recoverable solvents for water); and
(f) recovery of pollutants as by-products.
In addition to the effluent limitations covering discharges directly
into waterways, the constituents of the effluent discharge from a plan-"
within the industrial category which would interfere with, pass tnrouqh,
or otherwise be incompatible with a well designed and operated publicly
owned activated sludge or trickling filter wastewater treatment plant
were identified. A determination was made of whether the introduction
of such pollutants into the treatment plant should be completely
prohibited.
EFFLUENT REDUCTION ATTAINABLE BY THE APPLICATION OF THE BEST AVAILABLE
DEMONSTRATED CONTROL TECHNOLOGIES, PROCESSES, OPERATING METHODS OR OTHER
ALTERNATIVES.
377
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Based upon the information contained in Sections III through X of this
report, the following determinations were made on the degree of effluent.
reduction attainable with the application of new source standards for
the various categories of the inorganic chemicals industry.
The process water, cooling water and blowdown guidelines for new sources
are identical to those based on best available technology economically
achievable.
Category 1 Chemicals
No discharge of process waste water pollutants to navigable waters is
required for the new sou-re performance standard. This is achievable by
application of the best practicable technology currently available.
Category 2 Chemicals
The new source performance standards for all chemicals in Category 2,
except soda ash, require no discharge of process waste water pollutants
to navigable waters. This standard may be achieved by the incorporation
of best available technologies economically achievable into new sources.
Sodium Carbonate (Soda Ash - Solvay)
An alternative process for the manufacture of soda ash with zero
pollutants in process water discharge exists, the mining and processing
of trona. Because of this, a no discharge to navigable waters of
pollutants in process waste water is the new source performance standard
for manufacture. The calcium chloride raw waste load of the Solvay
process is such that 10 to 15 percent of it can supply the total volume
of the U.S. market for calcium chloride, so the potential for waste
disposal through this channel is limited. Large capital costs are
involved to bring Solvay process plants to the capability of no
discharge, and the disposal of the unmarketable by-product calcium
chloride is difficult due to its extreme solubility.
Category 3 Chemicals
Teh new source performance standards for all chemicals in Category 3,
except titanium, require no discharge of process waste water pollutants
to navigable waters. This standard may be achieved by the incorporation
of best available technologies economically achievalbe into new sources.
Titanium Dioxide (Chloride and Sulfate Processes)
Although research is currently being conducted to determine the
feasibility of acid recovery and recycle of process water, many-problems
remain unsolved. As such, it is not considered feasible to require this
technology to be incorporated into new facilities. The new source
378
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performance standards for titanium dioxide require the same degree of
effluent reduction attainable by the application of best available
technology economically achievable, as presented in Section X.
PRETREATMENT STANDARDS FOR NEW SOURCES
Plants whose wastewater discharges are characterized by inorganic
materials or by presence of harmful materials that interfere with
operation of biological systems are not suited to use of conventional
secondary waste treatment. Extreme segregation (that is, limiting the
sewered discharge to sanitary and other organic wastes) or pretreatment
is required by such manufacturing plants.
379
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SECTION XII
ACKNOWLEDGMENTS
The preparation of this report was accomplished through the efforts of
the staff of General Technologies corporation, a subsidiary of Versar,
Inc., Springfield, Va., under the direction of Dr. Pobert G. Shaver.
Mr. Elwood E. Martin, Project Officer, Effluent Guidelines Divi.iion,
through his assistance, leadership, and advice has made an invaluable
contribution to the preparation of this report. Mr. Martin provided a
careful review of the draft report and suggested organizational,
technical and editorial changes. He was also most helpful in miking
arrangements for the drafting, presenting, and distribution of the
completed report.
Mr. Allen Cywin, Director, Mr. Ernst Hall, Assistant Direcror, Effluent
Guidelines Division and Mr. Walter J. Hunt, Chief, Effluent Guidelines
Development Branch, offered many helpful suggestions during the program.
Mr. James Hemminger, Effluent Guidelines Division, provided extensive
technical and editorial assistance.
Acknowledgement and appreciation is given to the secretarial staff of
the Affluent Guidelines Division for their efforts in typing and final
report preparation, especially to: Ms. Kaye Starr, and Ms. Chris Miller,
and Ms. Sharon Ashe.
Appreciation is also extended to the following trade associations and
corporations for assistance and cooperation rendered to us in this
program:
Chlorine Institute
Manufacturing Chemists Association
Salt Institute
Water Pollution Control Federation
Airco Corooration
Alcoa
Allied Chemical Corporation
American Cyanamid Corporation
Aqua-Chem
BASF Wyandotte
Bird Machine Company
Cabot corporation
Calgon Corporation
Chemical Separations corporation
Diamond Shamrock
Dorr Oliver
Dow Chemical
E.I. DuPont de Nemours & Company
Duval Corporation
381
-------
Eimco
Envirogenics Company
Essex Chemical
Ethyl Corporation
FMC
Freeport Sulfur
Goslin Birmingham, Inc.
Gulf Environmental Systems Company
Harshaw Chemical
Hooker Chemical
International Mineral S Chemical Corp.
International Salt
Kaiser Chemical
Leslie Salt
Midwest Carbide
Monsanto
Morton Salt Company
MSA Research, Inc.
National Lead Industries
New Jersey Zinc
Occidental Petroleum
Office of Saline Water, U.S. Department of Interior
Olin Corporation
Pearsall Chemical
Potash Institute of America
PPG Corporation
Resources Conservation Company
Rice Engineering and Operating, Inc.
RMI Corporation
Rohm and Haas Corporation
Sherwin Williams
Stauffer Chemical
Union Carbide
U.S. Borax Corporation
U.S. Bureau of Mines, Reno Research Center
U.S. Lime, Division Flintkote Company
Van de Mark Chemical
Vicksburg Chemical
Water Services Corporation
Davy Power Gas, Inc.
Also, our appreciation is extended to the individuals of the Staff of
General Technologies Corporation for their assistance during this
program. Specifically, our thanks to:
Mr. E.F. Abrams, Chief Engineer
Mr. L.C. McCandless, Senior Chemical Engineer
Dr. C.L. Parker, Senior Chemical Engineer
Mr. R.C. Smith, Jr., Senior Chemical Engineer
Mr. E.F. Rissmann, Environmental Scientist .
382
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Acknowledgement and appreciation is also given to the
secretarial staffs of General Technologies Corpora-
tion for their efforts in the typing and drafts and
necessary revisions.
We wish to extend our thanks to personnel in the EPA Regional Offices of
regions II, III, IV, V, and VI for many helpful suggestions and advice
offered to us on this program.
The members of the working group/steering committee who coordinated the
internal EPA review are!
Mr. Walter Hunt, Effluent Guidelines Division Mr. Elwood Martin,
Effluent Guidelines Division Mr. James Hemminger, Effluent Guidelines
Division Mr. George Key, Office of Research and Monitoring Mr. Herbert
Skowronek, National Environmental Research Center; Cincinnatta (Edison)
Mr. John Savage, Office of Planning and Evaluation Mr. Allan Eckert,
Office of General Counsel Mr. Gary Amendala, Region V Mr. John Davis,
Region III Mr. Emery Lazar, Office of Solid Wastes Management Program
383
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SECTION XIII
REFERENCES
tReferences 1-12 were used to characterize the industry and
develop its profile and statistics in Sections III and IV1
1. Popper, H., "Modern Cost Engineering Techniques", McGraw-Hill
Book Co., 1970.
2. Shreve, R.N., "Chemical Process Industries", 3rd Ed., McGraw-
Hill Book Co., 1967.
3. Perry, J.N., "Chemical Engineer's Handbook", 4th Ed., McGraw-
Hill Book Co. , 1962.
U. Kirk, R.E. and Cthmer, D.F., "Encyclopedia of Chemical Tech-
nology", 2nd Ed., Wiley-Interscience, 1963.
5. Faith, W.L., Keyes, D.B., and Clark, R.L. , "Industrial
Chemicals", 3rd Ed., John Wiley & Sons, Inc. (1965).
6. Keyes, D.B. and Deem, L.G., "Chemical Engineer's Manual",
Prof. Ed., John Wiley & Sons, Inc. (1942).
7. Davidson, R.L., "Successful Process Plant Practices", McGraw-
Hill Book Co. (1958) .
8. U.S. Bureau of Mines, "Producers of Salt in the United States-
1965".
9. Hicks, T.G. , "Standard Handbook of Engineering Calculations",
McGraw-Hill Book Co. (1972).
10. Chemical and Engineering News, June 4, 1973, pp. 12-13.
11. "Study of the Economic Impact of the Cost of Alternative
Federal Water Quality Standards on Ten Inorganic Chemicals",
Borz-Allen Public Administration Services, Inc., Washington,
D.C. (1973) .
12. Chemical Marketing Reporter, June 4, 1973.
13. "Methods of Chemical Analysis for Water and Wastes", FWPCA,
p. 72 (1971).
14. Banksdale, J., "Titanium", The Ronald Press Company, New York,
N.Y., 2nd Edition.
-------
15. Fairall, J.M., Marshall, L.S., Rhines, C.E., "Guide tor
Conducting an Industrial Waste Survey", Draft only, U.S.
Environmental Protection Agency, Cincinnati, Ohio (1972).
16. Sawyer, Clair N., "Chemistry for Sanitary Engineers", McGraw-
Hill Book Co., New York, N.Y. (1960).
17. "Public Health Service Drinking Water Standards", Revised
1963, U.S. Department of Health, Education and welfare,
U.S. Public Health Service Publication No. 956, U.S.
Government Printing Office, Washington, D.C. (1962).
18. "Chemical and Engineering News", May 7, 1973, pp. 8-9.
19. "The Economics of Clean Water", Vol. Ill, Inorganic Chemicals
Industry Profile, U.S. Dept. of the Interior, Federal Warer
Pollution Control Administration (March 1970).
20. Final Technical Report, Contract No. 68-01-0020, Industrial
Waste Study of Inorganic Chemicals, Alkalis and Chlorine,
General Technologies Corp., July 23, 1971 (EPA).
21. Chemical and Engineering News, February 19, 1973, pp. 8-9.
22. Besselievre, Edward B., "The Treatment of Industrial Wastes",
McGraw-Hill Book Co., p. 56 (1968).
23. Personal Communications, EIMCO Division, Enviro-Tech Corp.,
Salt Lake City, Utah.
2Ui Personal Communications, Dorr-Oliver Co., Stamford Conn.
25. "The Economics of Clean Water", Vol. Ill, Inorganic Chemicals
Industry Profile, Contract No. 14-12-592, U.S. Department of
the Interior, Federal Water Pollution Control Administration
(March, 1970) .
26. "Sludge Dewatering: The Hardest Phase of Waste Treatment",
Environmental Science and Technology, Vol. 5, No. 8, August:
1971, pp. 670-671.
27. Jacobs, H.L., "In Waste Treatment — Know Your Chemicals,
Save Money", Chemical Engineering, May 30, 1960, pp. 87-91.
28. Sonnichsew, J.C., Jr., Engstrom, S.L., Kolesar, D.C. and
Bailey, G.C., "Cooling Ponds - A Survey of the State of
the Art", Hanford Engineering Development Laboratory,
Report HEDL-TME-72-101 (Sept. 1972).
29. Unpublished Information, E.I. DuPont Letter (May 3, 1973).
386
-------
30. Unpublished Information, E.I. DuPont Letter (May 16, 1973).
31. Kumar, J., "Selecting and Installing Synthetic Pond-Linings",
Chemical Engineering, February 5, 1973, pp. 67-68.
32. Rapier, P.M., "Ultimate Disposal of Brines From Municipal
Wastewater Renovation", Water-1970, Chemical Engineering
Proaress Symposium Series 107, Vol. 67, p. 340-351.
33. Browning, Jon E., "Activated Carbon Bids for Wastewater
Treatment Jobs", Chemical Engineering, Sept. 7, 1970,
pp. 32-34.
34. "N^w ^reatment Cuts Water Bill", Chem. Week, June 10, 1970,
p. 40.
35. Ahlqren, Richard M., "Membrane vs. Resinous Ion-Exchange
Demin^ralization", Industrial Water Engineering, Jan. 1971,
pp. 12-15.
36. Grits, George J., "Economic Factors in Water Treatment",
Industrial Water Engineering, Oct. 1971, pp. 22-29.
37. "Applications of Ion Exchange", 111, Rohm 8 Haas Bulletin
No'. 94, July 16-18, 1969.
38. Higgins, I.P. and Chopra, R.C., "Chem-Seps Continuous lon-
Exchariqe Contactor and its Application to De-mineralization
Processes", Presentation, Conf. of Ion Exchange in the
Process Ind., Imperial Coll. of Sci. 8 Tech., London, July
16-18, 1969.
39. Kunin, Robert and Downing, Donald G., "New Ion Exchange
Systems for Treating Municipal and Domestic Waste Effluents",
Water-1970, Chem. Eng. Prog. Sym. Series 107, Vol. 67, pp.
575-580 (1971).
40. Downing, D.G., Kunin R., and Polliot, F.X., "Desal Process-
Economic Ion Exchange System for Treating Brackish and Acid
Mine Drainage Waters and Sewage Waste Effluents", Water-1968,
Chem. Eng. Prog. Sym. Series 90, Vol. 64 (1968).
41. Parlar.te, R. , "Comparing Water Treatment Costs", Plant
Engineering (May 15, 1969) .
42. Brigham, E.G. and Chopra, R.C., "A Closed Cycle Water System
for Ammonium Nitrate Producers", presented, Int. Water Conf.,
^he Eng. Soc. of Western Penn., 32nd Annual Meeting,
Pittsburgh, Pa. (November 4, 1971) .
387
-------
43. Holzmacher, Robert G., "Nitrate Removal from a Ground Water
Supply", Water and Sewage World (reprint).
44. "Ion Exchangers Sweeten Acid Water", Envir. Sci. f/ Tech.,
Vol. 5, No. 1 pp. 24-25 (January 1971).
45. Sawyer, George A. , "New Trends in Wastewater Treatment and
Recycle", Chemical Engineering, pp. 120-128 (July 24, 1972).
46. Dryden, Franklin D., "Demineralization of Reclaimed Water",
Ind. Water Eng., pp. 24-26 (August/September, 1971).
47. Seels, Frank H., "Industrial Water Pretreatment", Chemical
Engineering Deskbook Issue (February 26, 1973).
48. Calmon, Calvin, "Modern Ion Exchange Technology", Ind. Water
Eng., pp. 12-15 (April/May 1972).
49. "Demineralizing, Dealkalinization, Softening", Chemical
Separations Corporation Bulletin.
50. "Reverse Osmosis Principles and Applications", text by Roga
Systems Division Staff, Gulf Environmental Systems Company,
P.O. Box 608, San Diego, California, 92112.
51. Kremen, S.S., "The Capabilities of Reverse Osmosis for
Volume Production of High-Purity Water and Reclamation of
Industrial Wastes" for Thirty-Second Annual Meeting of the
American Power Conference, Chicago, 111. (April 21-23, 1970).
52. Cruver, J.E. and Nusbaum, I., "Application of Reverse Osmosis
to Wastewater Treatment", presented at Water Pollution
Control Federation Meeting, Atlanta, Georgia (Oct. 8-13, 1972).
53. Kaup, Edgar C., "Design Factors in Reverse Osmosis", Chemical
Engineering, Vol. 80, No. 8, pp. 46-55 (April 2, 1973).
54. Myers, J.H., "Reverse osmosis Can Cut Cost of Water Treatment",
Industrial Water Engineering, pp. 25-30 (March 1970).
55. Rowland, H., Nusbaum, I. and Jester, F.J., "Consider RO for
Producing Feedwater", Power, pp. 47-48 (December 1971).
56. Witmer, F.E., "Low Pressure RO Systems - Their Potential in
Water Reuse Applications", paper presentation at Joint EPA-
AICHE Water Reuse Meeting, Washington, D.C. (April 23-27, 1973)
57. Channabasappa, K.C. and Harris, F.L., "Economics of Large-
scale Reverse Osmosis Plants", Ind. Water Eng., pp. 40-44
388
-------
(October 1970).
58. Resources Conservation Co., unpublished data and engineering
design and cost information.
59. Herrigel, H., Fosberg, T. , Stickney, W. and Perry C., Final
Report, "Operating Data of a Vertical Plane Surface, Falling
Film Evaporator Using Slurry and High Concentration Feeds",
OSW Contract No. 14-30-2939.
60. "El Paso Natural Participates in Promising Process for Warer
Recovery", The Pipeliner (December 1971).
61. Casten, James, Goslin-Birmingham Corp., unpublished data and
engineering design and cost information.
62. Prescott, J.H., "New Evaporation-Step Entry", Chemical
Engineering, pp. 30-32 (Dec. 27, 1971).
63. "Industrial Wastewater Reclamation with a 400,000 Gallon-Per-
Day Vertical Tube Evaporator, Design, Construction, and
Initial Operation", EPA Program No. 12020 GUT.
64. "Evaporator Tackles Wastewater Treatment", Chemical Engin-
e^ring, p. 68 (March 20, 1972).
65. Cosgrove, J., "Desalting: Future Looks Bright", Water and
Wastes Engineering, Vol. 9, No. 8, p. 43.
66. Houle, J.F. and Challis, J.A., "Industrial Use of Desalting
in Southern Puerto Rico", Water-1970, Chem. Eng. Prog. Sym.
Series 107, Vol. 67 (1971).
67. Patterson, J. and Minear, Roger A., "Wastewater Treatment
Technology", 2nd Edition, Report to Inst. of Envir. Coat:.,
State of Illinois, pp. 321-343 (January 1973).
68. "The Economics of Clean Water", Vol. Ill Inorganic Chemicals
Industry Profile, Contract No. 14-12-592, U.S. Dept of the
Interior, Federal Water Pollution Control Administration,
PD. 445-447 (March 1970).
69. Okey, Robert W., Envirogenics Company, Letter (May 14, 1973).
70. Gavelin, Gunnar, "Is Evaporation the Ultimate Solution to
Effluent Problems?" paper Trade Journal, pp. 102-103 (June
10. 1968) .
71. Ahlgren, Richard M., "A New Look at Distillation", Ind.
Water Eng., pp. 24-27 (October 1968).
389
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72. Young, K.G., "Summary of Design and Economic Considerations
for Complete Drying and Disposal of the Inorganic Salt
Slurry Produced by the RCC M225B Brine Concentrator",
Resources Conservation Company, Unpublished Analysis. (Using
Reference 72) .
73. W.L. Badger Associates, "Conversion of Desalination Plant
Brines to Solids", OSW Contact Report #636 (October 1970).
74. Witt, Phillip A., Jr., "Disposal of solid Wastes", Chemical
Engineering, pp. 67-77 (October 4, 1971).
75. Unpublished Data, E.I. DuPont Company.
76. Goodheart, L.B., Rice Engineering & Operating, Inc., General
Cost Letter (May 4, 1973) .
77. "Well-Disposal Is No Panacea", Chemical Engineering, pp. 26-23
(May 1972).
78. Wright, J.L., "Disposal Wells are a Worthwhile Risk", Mining
Engineering, pp. 63-72 (August 1970).
79. Ramey, B.J., "Deep-Down Waste Disposal", Mech. Eng., pp. 28-31
(August 1968) .
80. "Injection Wells Pose a Potential Threat", Envir. Sci. 6 Tech.,
Vol. 6, No.2, pp. 120-122 (February 1972).
81. "The Economics of Clean Water", Vol. Ill, Inorganic Chemicals
Industry Profile, Contract No. 14-12-592, Federal Water Poll.
Control Admin., U.S. Department of the Interior (March 1970).
82. Fader, Samuel W., "Barging Industrial Liquid Wastes to Sea",
J. Water Poll. Control Fed., Vol. 44, No. 2, pp. 314-318
(February 1972).
83. "At Sea About Chemical Wastes", Chemical Week, pp. 133-136
(October 14, 1967).
84. "Tide May be Going Out for Waste Disposal at Sea", Chemical
Week, pp. 49-53 (October 28, 1970) .
85. Unpublished Data, E.I. DuPont Co., Letter and verbal commun-
ications (May 16, 1973) .
390
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SECTION XIV
GLOSSARY
^he -total titratable hydrogen ion content of the solution is defined as
the acidity. Acidity is expressed in mg/1 of free hydrogen ion.
Adsorption
Condensation of the atoms, ions or molecules of a gas, liquid or
dissolved substance on the surface of a solid called the adsorbent. The
best, known examples are gas/solid and liquid/ solid systems.
Air Pollution
The presence in the air of one or more air contaminants in quantities
injurious to human, plant, animal life, or property, or which
unreasonably interferes with the comfortable enjoyment thereof.
Alkalinity
Total titratable hydroxyl ion concentration of a solution. In wat^r
analysis, alkalinity is expressed in mg/1 (parts per million) of calci.um
carbonate.
Ash
The solid residue left after incineration in the presence of oxygen.
A dry collection device for recovery of particulate matter trom gas
streams.
Bar om et r i^c_ Condenser
Device, operating at barometric pressure, used to change vapor into
liquid by cooling.
Biochemical Oxygen Demand, BOD5
The BOD test is an empirical bioassay-type procedure which measures the
dissolved oxygen consumed by microbial life while assimilating and
oxidizing the organic matter present. Standard test conditions include
dark incubation at 20°C for a specified time period (usually 5 days) .
Blowdown
391
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A discharge from a system, designed ,to prevent a buildup of some
materials, as in a boiler to control dissolved solids.
Brine
An aqueous salt solution.
Calcination
The roasting or burning of any substance to bring about physical or
chemical changes; e.g., the conversion of limestone to quicklime.
Carbonat ion
Treatment with carbon dioxide gas.
Catalytic_Converter
A unit containing a packed or fluidized bed of catalyst.
Caustic
Capable of destroying or eating away by chemical action. Applied to
strong bases and characterized by the presence of hydroxyl ions in
solution.
A device having a rotating container in which centrifugal force
separates substances of differing densities.
Cj2emJ.cal_Oxygen_Demandx_COp
Its determination provides a measure of the quantity of oxygen required
to oxidize the organic matter (or other oxidizable matter) in a waste
sample, under specific conditions of oxidizing agents, temperature and
time. The general method is applied to waste samples having an organic
carbon concentration greater than 15 mg/1.
Coke
The carbonaceous residue of the destructive distillation (carbonization)
of coal or petroleum.
Conditioning
A physical and/or chemical treatment given to water used in the plant or
discharged.
Conductivity, Electrical
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The ability of a material to conduct a quantity of electricity
transferred across a unit area, pe.r unit potential gradient per unit
time. In practical terms, it is used for approximating the salinity or
total dissolved solids content of water.
Coo ling__ Water
Water which is used to absorb waste heat generated in tne process.
Cooling water can be ei-ther contact or non-contact.
Copperas
Fprrous sulfate.
Cyclone Separator
A. mechanical device which removes suspended solids from gas streams.
alization
The removal from water of mineral contaminants usually present in
ionized form. The methods used include ion-exchange techniques, flash
distillation or electrolysis.
^l§.£tT2§t a t i c_ P r ecipitator
A gas cleaning device using the principle of placing an electrical
charge on a solid particle which is then attracted to an oppositely-
charged collector plate.
Filtrate
Liquid after passing through a filter.
Filtration
Removal of solid particles from liquid or particles from air or gas
stream through a permeable membrane.
Flocculation
The combination of aggregation of suspended solid particles in such a
way that they form small clumps. The term is used as a synonym for
coagulation.
Fluidized Bed Peactor
A reactor in which finely divided solids are caused to behave like
fluids due to their suspension in a moving gas or liquid stream.
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Gas Washer_(or Wgt Scrubber)
Apparatus used to remove entrained solids and other substances from a
gas stream.
Hardness (Total)
The characteristic of water generally accepted to represent the total
concentration of calcium and magnesium ions, usually expressed as mq/1
of calcium carbonate.
Heavy Metal
One of the metal elements not belonging to the alkali or alkaline earth
group. In this study, the classification includes titanium, vanadium,
iron, nickel, copper, mercury, lead, cadmium, and chromium.
Ion Exchange
A reversible chemical reaction between a solid and a fluid by means of
which ions may be interchanged from one substance to another. The
customary procedure is to pass the fluid through a bed of the solid,
which is granular and porous and has a limited capacity for exchange.
The process is essentially a batch type in which the ion exchanger, upon
nearing depletion, is regenerated by inexpensive salts or acid.
Ki. 1 n_^Rot ar y)
A large cylindrical mechanized type of furnace used for calcination.
Membrane
A thin sheet of synthetic polymer, through the apertures of which small
molecules can pass, while larger ones are retained.
Mother_liquor
The solution from which crystals are formed.
Multi-Effect Evaporator
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 is used to supply energy for
the next. Such units are called "effects" in engineering parlance as,
e.g., a triple effect evaporator.
Oleum or Fuming_Sulfuric-iAcid
A solution of sulfur trioxide in sulfuric acid.
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Is a measure of the relative acidity or alkalinity of water. A pH value
of 7.0 indicates a neutral condition; less than 7 indicates a
predominance of acids, and greater than 7, a predominance of alkalis.
There is a 10-fold increase (or decrease) from one pH unit level to the
next, e.g., 10-fold increase in alkalinity from pH 8 to pH 9.
Pi an t _E f f lu e n t _o r _ Di§_cha rg_e_ a f_t er_ Treatment
The waste water discharged from the industrial plant. In this
definition, any waste treatment device (pond, trickling filter, etc.) is
considered part of the industrial plant.
Pretreatment
The necessary processing given materials before they can be properly
utilized in a process or treatment facility.
Process Efflugnt or Discharge
The volume of waste water emerging from a particular use in the plant.
Process^Water
Water which is used in the internal plant streams from wnich products
are ultimately recovered, or water which contacts either the raw
materials or product at any time.
Reyerj3e_Osmosis
A method involving application of pressure to the surface of a saline
solution forcing water from the solution to pass from the solution
through a membrane which is too dense to permit passage of salt ions.
Hollow nylon fibers or cellulose acetate sheets are used as membranes
since their large surface areas offer more efficient separation.
Sedimentation
The falling or settling of solid particles in a liguid, as a sediment.
Settling_Pond
A large shallow body of water into which industrial waste waters are
discharged. Suspended solids settle from the waste waters due to the
large retention time of water in the pond.
Sintering
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The agglomeration of powders at temperatures below their melting points.
Sintering increases strength and density of the powders.
Slaking
The process of reacting lime with water to yield a hydrated product.
Sj.udge
The settled mud from a thickener clarifier. Generally, almost any
flocculated, settled mass.
Slurry
A watery suspension of solid materials.
Sniff Gas f
The exhaust or tail gas effluent from the chlorine liquefaction and
compression portion of a chlor-alkali facility.
Solute
A dissolved substance.
Solvent.
A liquid used to dissolve materials.
Thickener
A device or system wherein the solid contents of slurries or suspensions
are increased by evaporation of part of the liquid phase, or by gravity
settling and mechanical separation of the phases.
!E2tal_Dissolved_Solids __ (TDS)
The total amount of dissolved solid materials present in an aqueous
solution.
Total Organic Carbon jTOC
A measurement of the total organic carbon content of surface waters,
domestic and industrial wast.es, and saline waters.
Solid particulate matter found in waste water streams, which, in most
cases, can be minimized by filtration or settling ponds.
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A measure of the opacity or transparency of a sediment-containing waste
stream. Usually expressed in Jackson units or Formazin units wnich are
essentially equivalent in the range below 100 units.
Wet Scrubbing
A gas cleaning system using water or some suitable liquid to entrap
particulate matter, fumes, and absorbable gases.
Waste Discharged
The amount (usually expressed as weight) of some residual substance
which is suspended or dissolved in the plant effluent.
^sste_Generated (Raw Wastel
The amount (usually expressed as weight) of some residual substance
generated by a plant process or the plant as a whole. This quantity is
measured before treatment.
Water_Pecirculation or Recycling
The volume of water already used for some purpose in the plant which is
returned with or without treatment to be used again in the same or
another process.
Wat er Us e
The total volume of water applied to various uses in the plant. It is
the sum of water recirculation and water withdrawal.
Water Withdrawal or Intake_
The volume of fresh water removed from a surface or underground water
source by plant facilities or obtained from some source external to the
plant. The effluent limitations guidelines for sodium dichromare and
byproduct sodium sulfate plants, based on the application of the best
available technology economically achievable, require no discharge of
process waste water pollutants to navigable waters.
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