v>EPA
United States
Environmental Protection
Agency
Office of Environmental Engineering
and Technology
Washington DC 20460
EPA-600/8-84-010
October 1984
Research and Development
The Cost Digest:
Cost Summaries of
Selected Environmental
Control Technologies
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EPA-600/8-84-010
October 1984
The Cost Digest:
Cost Summaries of
Selected Environmental
Control Technologies
by
Glenn DeWolf, Pat Murin, James Jarvis, and Mary Kelly
Radian Corporation
Austin, TX 78766
EPA Contract No. 68-02-3171
EPA Project Officer
John Milliken
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
Office of Environmental Engineering and Technology
Office of Research and Development
U.S. Environmental Protection Agency
Washington, DC 20460
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Notice
This document has been reviewed in accordance with U.S. Environmental
Protection Agency policy and approved for publication. Mention of trade names
or commercial products does not constitute endorsement or recommendation
for use.
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Acknowledgements
This work was supported by the Office of Environmental Engineering and
Technology Work Group on Costs of Environmental Control Technologies under
the overall guidance of Steven Reznek (formerly ORD, Washington) and Kurt
Riegel (ORD, Washington). Gene Tucker {IERL, RTP) was chairman of the work
group supported by members John Milliken (IERL, RTP) (Project Officer), Alden
Christiansen (IERL, Cincinnati), Robert Clark (MERL, Cincinnati), Albert Klee
(IERL, Cincinnati), Robert Smith (MERL, Cincinnati, now retired), and Richard
Eilers (MERL, Cincinnati). In addition, other EPA staff members provided helpful
suggestions and comments.
This report was prepared by Glenn DeWolf, James Jarvis, Pat Murin, and Mary
Kelly of Radian Corporation with support and contributions from other staff
members. It was prepared in fulfillment of Contract No. 68-02-3171, Work
Assignments 26 and 47.
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Preface
Environmental policy planners, permit writers and reviewers, management
and budget officials, and developers of environmental control technologies use
cost information on environmental control technologies to make effective
decisions. Reliable, concise, and understandable cost data on capital invest-
ment, operating expenses, and revenue requirements serve to reduce the
manager's level of uncertainty, and consequently improve his overall per-
formance in attainment of environmental policy goals.
To provide reliable, concise, and understandable cost data, EPA's Office of
Environmental Engineering andTechnology(OEET) presents THE COST DIGEST
as the first report in a series of publications on costs of environmental control
technologies. This volume provides summary cost data for 25 selected
environmental control technologies in the following areas: the treatment of
drinking water and wastewaters, and the control of airborne participate matter
and sulfur oxides from stationary sources. In addition to cost data on capital
investment and operating expenses for each technology, we have given special
attention to providing facility design descriptions and control technology
performance characteristics. These technology descriptions feature a narrative
summary, a process flow chart with battery limits which illustrate the modules
included in the cost estimates, key design parameters, and performance
characteristics. The major variables affecting costs for each technology are also
discussed. Although we have attempted to select representative or typical
design configurations for each technology, the information on design parameters
and performance characteristics is essential to effective use of associated cost
data.
Two additional publications for the OEET series on costs of environmental
control technologies are currently in preparation and review. These are "COSTS
OF ENVIRONMENTAL CONTROL TECHNOLOGIES—GRANULAR ACTIVATED
CARBON APPLICATIONS IN WATER AND WASTEWATER TREATMENT" and
"COSTS OF ENVIRONMENTAL CONTROL TECHNOLOGIES—PARTICULATE
MATTER CONTROL FOR INDUSTRIAL AND UTILITY BOILERS." Instead of
presenting summary cost information for complete control technology systems,
these volumes will provide more detailed engineering cost data for the specific
modules which make up the control technology systems. This feature will allow
for cost estimates to be more tailored to specific cases. By contrast, THE COST
DIGEST allows the user to derive costs of typical, but mostly fixed, designs for
control systems.
It is hoped that, as an executive summary of environmental technology cost
information, THE COST DIGEST will be widely used by planners, budgeters,
technology developers, and managers in general who need quick reference to
easy-to-use, reliable cost data. We welcome comments on THE COST DIGEST
and suggestions for guiding and improving the OEET reports on costs of
environmental technologies.
IV
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Contents
Page
Acknowledgements jjj
Preface iv
1.0 Introduction and User Guide 1
1.1 Organization of the Report 1
1.2 Terminology and Format for Presenting Cost Estimates 2
1.3 Cost Updating 4
1.4 Sources of Information and Limitations 4
1.5 Considerations When Comparing Cost Estimates 5
1.6 Relating Costs to Consumer Prices 6
References 7
2.0 Drinking Water Treatment 8
2.1 Filtration Treatment Plants 10
2.1.1 Description 10
2.1.2 Design Basis and Costs 11
2.1.3 Major Variables Affecting Costs 12
2.2 Disinfection 13
2.2.1 Chlorine 13
2.2.2 Chlorine Dioxide 14
2.2.3 Ozone 16
2.2.4 ChHoramination 18
2.3 Granular Activated Carbon Treatment 19
2.4 Aeration 22
References 24
3.0 Wastewater Treatment 26
3.1 Conventional Secondary and Advanced Wastewater
Treatment 27
3.2 Stabilization Ponds and Aerated Lagoons 33
3.3 Land Treatment 36
3.4 Phosphorus Removal by Chemical Addition 39
3.5 Nitrification (Separate-Stage} 40
3.6 Granular Media Filtration 43
References 45
4.0 Paniculate Matter Collection 47
4.1 Multitube Cyclones 49
4.2 Electrostatic Precipitators 50
4.3 Fabric Filters 55
4.4 Venturi Wet Scrubbers 58
References 62
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Contents (continued)
Page
5.0 Flue Gas Desulfurization 64
5.1 Wet FGD Scrubbing Processes 64
5.1.1 Wet FGD Process Descriptions 64
5.1.2 Design Basis and Costs 68
5.1.3 Major Variables Affecting Costs 71
5.1.4 Utility Boiler FGD Systems 71
5.1.5 Industrial Boiler FGD Systems 74
5.2 Lime Spray Drying Process 75
5.2.1 Process Description 75
5.2.2 Design Basis and Costs 77
5.2.3 Major Variables Affecting Costs 77
References 80
Appendix A — Methods for Adjusting Data 82
A.1 Format, Cost Factors, and Unit Prices 82
A.2 Unit Annualized Cost Calculations 83
A.3 Updating Costs 86
A.4 Interest During Construction 86
A.5 Location Factors 87
References 87
Appendix B — Glossary 89
Appendix C — Conversion of English to International System
(SI) Units 91
Appendix D — Miscellaneous Conversion Factors 92
VI
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List of Figures
Figure Page
Section 2
2-1 Conventional filtration system for drinking water treatment 10
2-2 Filtration plants for drinking water treatment
Total capital investment (March, 1980 dollars) 12
.2-3 Filtration plants for drinking water treatment
Net annual operating expenses (March, 1980 dollars). 12
2-4 Filtration plants for drinking water treatment
Unit annualized cost (March, 1980 dollars) 12
2-5 Chlorination system for drinking water treatment 13
2-6 Chlorination system for drinking water treatment
Total capital investment (March, 1980 dollars) 14
2-7 Chlorination system for drinking water treatment
Net annual operating expenses (March, 1980 dollars) 14
2-8 Chlorination system for drinking water treatment
Unit annualized cost (March, 1980 dollars) 14
2-9 Chlorine dioxide system for drinking water treatment 15
2-10 Chlorine dioxide system for drinking water treatment
Total capital investment (March, 1980 dollars) 15
2-11 Chlorine dioxide system for drinking water treatment
Netannuakoperating expenses (March, 1980 dollars) 16
2-12 Chlorine dioxide system for drinking water treatment
Unit annualized cost (March, 1980 dollars) 16
2-13 Ozonation system for drinking water treatment 17
2-14 Ozonation system for drinking water treatment
Total capital investment (March, 1980 dollars) 17
2-15 Ozonation system for drinking water treatment
Net annual operating expenses (March, 1980 dollars) 17
2-16 Ozonation system for drinking water treatment
Unit annualized cost (March, 1980 dollars) 18
2-17 Chloramination system for drinking water treatment 18
2-18 Ammonia feed system for drinking water treatment by
Chloramination
Total capital investment (March, 1980 dollars) 19
2-19 Ammonia feed system for drinking water treatment by
Chloramination
Net annual operating expenses (March, 1980 dollars) 19
2-20 Ammonia feed system For drinking water treatment by
Chloramination
Unit annualized cost (March, 1980 dollars) 20
2-21 Granular activated carbon system for drinking water treatment ... 20
vn
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List of Figures
Figure Page
2-22 Granular activated carbon system for drinking water treatment
Total capital investment (March, 1980 dollars) 21
2-23 Granular activated carbon system for drinking water treatment
Net annual operating expenses (March, 1980 dollars) 21
2-24 Granular activated carbon system for drinking water treatment
Unit annualized cost (March, 1980 dollars) 22
2-25 Aeration systems for drinking water treatment 23
2-26 Aeration for drinking water treatment
Total capital investment (March, 1980 dollars) 24
2-27 Aeration for drinking water treatment
Net annual operating expenses (March, 1980 dollars) 25
2-28 Aeration for drinking water treatment
Unit annualized cost (March, 1980 dollars) 25
Section 3
3-1 Conventional secondary treatment system for wastewater 28
3-2 Advanced wastewater treatment system 29
3-3 Conventional secondary and advanced wastewater treatment
Total capital investment (March, 1980 dollars) 32
3-4 Conventional secondary and advanced wastewater treatment
Net annual operating expenses (March, 1980 dollars) 32
3-5 Conventional secondary and advanced wastewater treatment
Unit annualized cost (March, 1980 dollars) 33
3-6 Stabilization pond or aerated lagoon system for wastewater
treatment 34
3-7 Stabilization ponds and aerated lagoons for wastewater
treatment
Total capital investment (March, 1980 dollars) 35
3-8 Stabilization ponds and aerated lagoons for wastewater
treatment
Net annual operating expenses (March, 1980 dollars) 35
3-9 Stabilization ponds and aerated lagoons for wastewater
treatment
Unit annualized cost (March, 1980 dollars) 36
3-10 Land treatment system for wastewater 37
3-11 Land treatment for wastewater treatment
Total capital investment (March, 1980 dollars) 38
3-12 Land treatment for wastewater treatment
Net annual operating expense (March, 1980 dollars) 38
3-13 Land treatment for wastewater treatment
Unit annualized cost (March, 1980 dollars) 38
3-14 Phosphorus removal by chemical addition for wastewater
treatment 39
3-15 Phosphorus removal for wastewater treatment
Total capital investment (March, 1980 dollars) 40
3-16 Phosphorus removal for wastewater treatment
Net annual operating expenses (March, 1980 dollars) 41
VIII
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List of Figures
Figure page
3-17 Phosphorus removal for wastewater treatment
Unit annualized cost (March, 1980 dollars) 41
3-18 Separate-stage nitrification system for wastewater treatment .... 42
3-19 Nitrification (separate-stage) for wastewater treatment
Total capital investment (March, 1980 dollars) 43
3-20 Nitrification (separate-stage) for wastewater treatment
Net annual operating expenses (March, 1980 dollars) 43
3-21 Nitrification (separate-stage) for wastewater treatment
Unit annualized cost (March, 1980 dollars) 43
3-22 Granular media filter system for wastewater treatment 44
3-23 Granular media filtration for wastewater treatment
Total capital investment (March, 1980 dollars) 45
3-24 Granular media filtration for wastewater treatment
Net annual operating expenses (March, 1980 dollars) 45
3-25 Granular media filtration for wastewater treatment
Unit annualized cost (March, 1980 dollars) 45
Section 4
4-1 Illustration of collection efficiency versus particle diameter 48
4-2 Multitube cyclone system for paniculate matter collection 49
4-3 Multitube cyclone system for paniculate matter collection
Total capital investment (March, 1980 dollars) 50
4-4 Multitube cyclone system for particulate matter collection
Net annual operating expenses (March, 1980 dollars) 51
4-5 Multitube cyclone system for particulate matter collection
Unit annualized cost (March, 1980 dollars) 51
4-6 Electrostatic precipitator system for particulate matter collection . . 52
4-7 Electrostatic precipitator system for particulate matter collection
Total capital investment (March, 1980 dollars) 54
4-8 Electrostatic precipitator system for particulate matter collection
Net annual operating expenses {March, 1980 dollars) 54
4-9 Electrostatic precipitator system for particulate matter collection
Unit annualized cost (March, 1980 dollars) 55
4-10 Fabric filter system for particulate matter collection 56
4-11 Fabric filter system for particulate matter collection
Total capital investment (March, 1980 dollars) 57
4-12 Fabric filter system for particulate matter collection
Net annual operating expenses {March, 1980 dollars) 57
4-T3 Fabric filter system for particulate matter collection
Unit annualized cost (March, 1980 dollars) 58
4-14 Venturi wet scrubber systemTor particulate matter collection 59
4-15 Venturi wet scrubber comparative fractional efficiency curves 60
4-16 Venturi wet scrubber system for particulate collection
Total capital investment (March, 1980 dollars) 60
4-17 Venturi wet scrubber system for particulate collection
Net annual operating expenses (March, 1980 dollars) 61
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List of Figures
Figure Page
4-18 Venturi wet scrubber system for participate collection
Unit annualized cost {March, 1980 dollars) 61
Section 5
5-1 Lime/limestone scrubbing process for flue gas desulfurization.... 65
5-2 Sodium alkali scrubbing (throwsway) process for flue gas
desulfurization 66
5-3 Dual alkali scrubbing process for flue gas desulfurization 67
5-4 Magnesium oxide scrubbing process for flue gas desulfurization .. 68
5-5 Wellman-Lord scrubbing process for flue gas desulfurization 69
5-6 Flue gas desulfurization systems for utility boilers
Total capital investment (March, 1980 dollars) 71
5-7 Flue gas desulfurization systems for utility boilers
Net annual operating expenses (March, 1980 dollars) 71
5-8 Flue gas desulfurization systems for utility boilers
Unit annualized cost (March, 1980 dollars) 72
5-9 Flue gas desulfurization systems for industrial boilers
Total capital investment (March, 1980 dollars) 72
5-10 Flue gas desulfurization systems for industrial boilers
Net annual operating expenses (March, 1980 dollars) 73
5-11 Flue gas desulfurization systems for industrial boilers
Unit annualized cost (March, 1980 dollars) 73
5-12 Lime spray drying process for flue gas desulfurization 76
5-13 Lime spray drying flue gas desulfurization systems for
utility boilers
Total capital investment (March, 1980 dollars) 78
5-14 Lime spray drying flue gas desulfurization systems for
utility boilers
Net annual operating expenses (March, 1980 dollars) 78
5-15 Lime spray drying flue gas desulfurization systems for
utility boilers
Unit annualized cost (March, 1980 dollars) 79
5-16 Lime spray drying flue gas desulfurization systems for
industrial boilers
Total capital investment (March, 1980 dollars) 79
5-17 Lime spray drying flue gas desulfurization systems for
industrial boilers
Net annual operating expenses (March, 1980 dollars) 80
5-18 Lime spray drying flue gas desulfurization systems for
industrial boilers
Unit annualized cost (March, 1980 dollars) 80
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List of Tables
Table Page
Section 1
1 -1 Technology Areas Addressed 1
1 -2 Format for Total Capital Investment 2
1 -3 Format for Net Annual Operating Expenses 2
Section 2
2-1 Drinking Water Contaminant Levels Based on Safe Drinking
Water Act 9
2-2 Charge Rate Profile for Typical Total Drinking Water System
Costs Based on Survey Data 9
2-3 Design Parameters for Typical Granular Activated Carbon
Systems for Drinking Water Treatment 21
2-4 Major Design Parameters for Aeration Basins and Towers for
Trihalomethane Removal in Drinking Water Treatment 23
Section 3
3-1 Typical Pollutant Removal Efficiency of Wastewater Treatment
Technology 26
3-2 Typical Influent Wastewater Composition 30
3-3 Design Parameters for Conventional Secondary Treatment
System 31
3-4 Design Parameters for Advanced Wastewater Treatment
System 31
3-5 Design Parameters for Pond Systems 34
3-6 Design Parameters for Land Treatment 37
3-7 Design Parameters for Nitrification (Separate-Stage) 42
3-8 Design Parameters for Granular Media Filtration 44
Section 4
4-1 Comparison of Major Paniculate Collection Systems 47
4-2 Comparison of Wet and Dry Collection Systems 48
4-3 Required Collection Efficiency for Typical Uncontrolled and
Hypothetical Controlled Paniculate Matter Concentrations 48
4-4 Multitube Cyclone Design Parameters 50
4-5 Precipitation Rate Parameters for Typical ESP Applications 53
4-6 Design Parameters for Model Electrostatic Precipitators 53
4-7 Design Parameters for Model Fabric Filter Systems 57
4-8 Venturi Wet Scrubber Design Parameters , 60
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List of Tables
Table Pa«e
Section 5
5-1 Comparison of Design Bases for Major Cost References 69
5-2 Effect of Changes in the Design Basis on PEDCo Total Capital
Investment Estimates 74
5-3 Effect of Changes in the Design Basis on TVA Total Capital
Investment Estimates : • • • 74
5-4 Effect of Coal Sulfur Content on Total Capital Investment and
Total Annual Operating Expenses for Utility Boiler Applications ... 75
5-5 Effect of Coal Sulfur Content and S02 Removal Efficiency on
Total Capital Investment and Total Annual Operating Expenses for
Industrial Boiler Applications 76
5-6 Design Bases for Utility and Industrial Lime Spray Dryer/Fabric
Filter Systems 77
Appendix A
A-1 Format and Factors for Total Capital Investment 83
A-2 Format for Net Annual Operating Expenses 84
A-3 Unit Prices Employed for Net Annual Operating Expenses 84
A-4 Basis for Fixed Charge Rate Annualized Cost Calculations 85
A-5 Annual Average and End-of-Quarter Capital Cost Indices 86
A-6 Factors for Calculating Interest During Construction 87
A-7 Cost Locality Factors 87
A-8 Power Cost Locality Factor 87
XII
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Sect/on 1
Introduction and User Guide
Planners and managers in government and industry
require cost information to aid in policy planning,
implementation, and administration. Much cost
information is available, but it is scattered in numbers
of published sources and not readily accessible for
quick reference. Furthermore, information from
different sources varies in the cost bases used, format
of presentation, level of detail, accuracy, documenta-
tion, and applicability for broad-based strategic
planning and analysis.
This manual was prepared to provide a concise and
easily understood graphical compilation of costs for
selected environmental control technologies in the
following areas:
• Drinking water treatment.
• Wastewater treatment (municipal and industrial).
• Paniculate matter control.
• Flue gas desulfurization.
A further goal was to present cost data in a consistent
format and terminoljogy to allow ready interpretation
without extensive analysts and calculations by the
user. Finally, this publication was intended as a
summary document which could be revised, updated,
and augmented In order to. .keep pace with new
developments'in key environmental control'technolo-
gtes.
Each of the four study areas addressed in this report
comprises several technologies as shown in Table 1 -
1. This list was selected by the Work Group on
Environmental Control Technologies, Office of
Environmental Engineering and Technology, within
the Office of Research and Development. The
technologies were chosen to represent those
environmental control options in the four study areas
currently of interest to policy planners.
1.1 Organization of the Report
Sections 1.2 through 1.6 provide guidance in
interpreting and using the cost data in this report.
Section 1.2 describes the terminology and format
used for presenting the cost data as well as the overall
methodology for cost development. Section 1.3
discusses cost updating. Section 1.4 discusses the
sources of data used in developing this manual and
limitations to its use. Section 1.5, a brief discussion
on general considerations when comparing cost
estimates, is presented to give tne reader some
Table 1-1. Technology Areas Addressed
Drinking Water Treatment Systems (Section 2)
Filtration treatment (conventional filtration, direct filtration, and
lime softening with conventional filtration)
Disinfection
Granular activated carbon treatment
Aeration
Wastewater Treatment Systems (Municipal and Industrial) (Section
3)
Conventional secondary (less than 30 mg/l BOD5) and
advanced wastewater treatment plants (less than 10 mg/l
BOD5)a
Stabilization ponds and aerated lagoons
Land treatment
Phosphorus removal by chemical addition
Nitrification
Granular media filtration
Particulate Matter Control Systems (Section 4)
Mechanical collectors (multitube cyclones)
Electrostatic precipitators
Fabric filters
Venturi scrubbers
Flue Gas Desulfurization Systems (Section 5)
Lime/limestone scrubbing
Non-regenerable sodium alkali (throwaway)
Dual alkali
Magnesium oxide
Wei I man-Lord
Dry scrubbing
Conventional secondary treatment is defined as achievement of
30 mg/l biochemical oxygen demand (BODs) and 30 mg/l
suspended solids (SS) or less in the treatment system effluent.
Advanced wastewater treatment achieves 10 mg/l BODs and 10
mg/l SS or less.
perspective in using the cost estimates in this report
and/or comparing them with cost estimates in other
references. Additional variables specific to individual
technologies are discussed in the individual
technology sections. Section 1.6 provides some
examples that show howenvironmental control costs
can be related to consumer prices.
The technology areas are discussed in Sections 2
through 5. Each section is divided into subsections for
each individual technology. Each subsection presents
a brief description highlighting the major technical
features of the process and the design basis for costs
presented. Graphical displays of total capital
investment, net annual operating expenses, and unit
annualized costs are provided. A discussion of major
technology-specific variables affecting costs completes
each technology subsection.
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The appendices contain details which supplement
material discussed in the main body of the report.
Appendix A describes the methodology used to
develop the costs presented for each technology area.
Appendix B is a glossary of cost-related and technical
terminology. The reader should confirm his/her
familiarity with the cost terms to verify that
definitions are consistent with the intended use of the
information. Appendix C is a list of conversion factors
for English and SI units, and Appendix D, miscellaneous
conversion factors between units of measure.
1.2 Terminology and Format for
Presenting Cost Estimates
Graphs are provided for each technology system
showing total capital investment, net annual
operating expenses, and unit annualized cost. These
cost terms have a specific meaning and usage within
the format discussed in a report by Uhl (1). A feature
of that format is the assignment of an item numberto
the individual cost elements comprising each of the
above three cost items. This numbering procedure is
used to ensure unambiguous interpretation of cost
elements in using the methodology of Uhl's report
even if different authors use a different terminology
to describe various cost items. Listings of the item
numbers, cost elements for total capital investment,
and cost elements for net annual operating expenses
are given in Table 1-2 and Table 1-3, respectively
Unit annualized cost is computed from fixed capital
charges and net annual operating expenses as
explained below. For simplification in the present
report, some individual cost elements were combined
into a single overall category. A line item with several
numbers next to it indicates that several individual
elements have been combined.
Total Capital Investment
All capital costs in the present report are shown as
total capital investment. Total capital investment
comprises 40 numbered cost elements as shown in
Table 1 -2 and is itself designated as item 41. Various
subtotals are shown in upper case letters in Table 1 -
2. Each succeeding subtotal is obtained by adding
cost elements to the preceding subtotal. With the
exception of direct cost items and land, all cost
elements are determined by multiplying a subtotal by
a factor. For example, a contingency allowance is
obtained by multiplying total bare module cost by a
factor. Factors used for each technology area are
shown in Table A-1, Appendix A. The direct costs for
each technology were adapted from costs in the
technical literature as discussed in Appendix A.
Direct cost items include both installed purchased
equipment and field fabricated process equipment.
Pumps are an example of installed purchased
equipment. Field fabricated process equipment
includes such items as the concrete basins used in
certain drinking water and wastewater treatment
processes. Some references refer to direct costs as
construction costs or installed equipment costs.
Table 1-2. Format for Total Capital Investment
Item No.a Item Costb
1-10
11
12-20
21
22
23
27
24-26, 28-30
31
32
33
34
35
36
37
38-40
41
Direct cost items
TOTAL DIRECT COST
Indirect cost items
(Engineering and
construction and
field expenses, other)
TOTAL BARE MODULE COST
Contingency
Contractor's fee
Retrofit increment
Other
TOTAL PLANT COST
Interest during
construction
Start-up
Other
TOTAL DEPRECIABLE
INVESTMENT
Land
Working capital
Other
TOTAL CAPITAL INVESTMENT
.c
{F, x Item 1 1 )
(Item 1 1 + Items
12 through 20)
(F2xltem 21)
(F3x Item 21)
(F4xltem 21)
(F.xltem 21)
(Item 21 +ttems
22 through 30}
(F5 x Item 31 )
(F6x Item 31)
(Fy x Item 31 )
{Item 31 + Items
32 through 34}
(Direct calcula-
tion of cost)
(F7 x Item 35)d
(fz x Item 35)
(Item 35 + Items
36 through 40)
"For a detailed discussion of individual line items and item numbers
see Uhl (1).
bFi, F2, etc., refer to factors for cost element or line item.
CAII installed equipment costs are added to arrive at total direct cost
for the system.
"Other methods are also possible. See Uhl (1).
Table 1-3. Format for Net Annual Operating Expenses
Item No.£
Item
53
56-58, 61
59,60
62
63
64
65
66
67
68,69
70
74
76
80
87
88-89
e
Raw materials
Labor6
Materials0
Steam
Power (Electricity)
Compressed air
Water
Fuel
Waste disposal
Other
PROCESSING EXPENSES (sum of Items
53 through 69)
Overhead (Fi x labor items)
Insurance and property taxes (F2 x
TDId)
NET OPERATING COSTS
General expense (F3 x TDl")
Other
NET ANNUAL OPERATING EXPENSES
"For a detailed discussion of individual line items and item
numbers see Uhl (1).
"includes operating direct labor, direct supervision, maintenance
labor, and labor burden.
Includes maintenance materials and operating supplies.
''TDI = total depreciable investment; see Table 1-2.
eNo item number was provided for this line item.
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When indirect costs such as engineering and
supervision and construction field expenses are
added to the direct costs, the total bare module cost is
obtained. Contingency and contractor's fees added to
the total bare module cost yield total plant or system
cost. Two additional cost elements which sometimes
are capitalized include loan interest during construc-
tion and start-up costs incurred during initial
operation of a new facility. If these costs are not
capitalized but are treated directly as an annual
expense, the total plant cost and total depreciable
investment are identical. In this report, however,
construction interest and start-up costs are capitalized
and added to the total plant cost to obtain total depre-
ciable investment. To obtain the total capital invest-
ment, the cost of land and working capital is added to
the total depreciable investment
Net Annual Operating Expense
Net annual operating expense refers to direct cash
expenses of operation and maintenance as well as
indirect items including overhead, insurance and
property taxes, and general expenses. Inclusion of
depreciation, a non-cash expense, would produce
total annual operating expenses rather than net
annual operating expenses. The elements of net
annual operating expenses are shown in Table 1 -3.
Part of the net annual operating expenses is
processing expenses. These expenses are commonly
referred to as O&M or operating and maintenance
expenses. Because the term O&M is not universally
defined ascomprising the same cost elements, its use
has been avoided in this report. Cost elements that
make up processing expenses are determined directly
from operating requirements and corresponding unit
prices. Items added to processing expenses to
generate the net annual operating expenses can be
obtained by multiplying a factor times another cost
element. In this report overhead was obtained as a
factor times labor cost; insurance and property taxes
and general expenses as a factor times total
depreciable investment. As with capital cost
elements discussed previously, each line item is
assigned a number. And, again for simplification in
this report, some line items have been combined so
that in some cases several numbers appear in the
item number columns.
Unit Annualized Cost
The unit annualized cost is the annualized cost
divided by the annual capacity of the process to yield
cost per unit of capacity such as cents per thousand
gallons or cents per kilowatt-hour. The annualized
cost is the sum of net annual operating expenses and
additional cost elements. The additional cost
elements added to net annual operating expenses
cover depreciation, cost of financing, and an
allowance for income taxes. Annualized cost is
equivalent to the minimum annual revenue require-
ment for the project. The unit annualized cost is,
therefore, equivalent to the minimum unit annual
revenue requirement or unit price for the pollution
control service performed.
A common method for including depreciation and
costs of financing is to use a capital recovery factor
where these cost elements are lumped into a single
number. In this report, a form of capital recovery
factor called the fixed charge rate is used. Typical
financing assumptions were used to develop the unit
annualized cost. This method and the assumptions,
discussed in Appendix A, account for depreciation,
cost of financing, income taxes, and the effect of an
investment tax credit lumped into a single number.
Data Presentation
Certain key features of the cost data presented in this
report include:
• Data are presented graphically. Total, capital
investment, net annual operating expenses, and
unit annualized cost are plotted against a system
capacity variable. In some cases, multiple curves
are shown on a graph to illustrate cost variations
caused by major variables specific to a technology.
For drinking water and wastewater treatment,
costs are given as a function of plant capacity in
millions of gallons per day {mgdj. For particulate
control systems, the cost data are plotted against
actual cubic feet per minute of gas stream flow,
fuel firing rate for fired process or industrial boiler
equipment, and megawatt generating capacity for
utility boilers. Because FGD systems are used
primarily on industrial and utility boilers, megawatt
generating capacity and fuel firing rate in Btu/hr
are the major variables against which costs are
plotted. These choices were based on common
usage in existing cost references for these
technology areas. Conversion factors between gas
flow rate, megawatt generating capacity, and fuel
firing rate are provided in Appendix D.
• Cost data are presented for entire treatment sys-
tems rather than individual system components.
This permits the user to obtain a typical pollution
control system cost without extensive computa-
tional and design exercises. References used as
sources for cost data from which costs in this
report were adapted provide greater detail on
component costs, but require selection of system
parameters, addition of individual component
costs to obtain total system costs, and other
calculations. These have been done for the user for
a typical or representative design and application
for each technology.
• Costs presented for each technology are for a
typical or representative design and application.
Site-specific factors will result in actual system
costs that might vary significantly from the values
reported here. Some of the reasons for these
-------
variations are discussed in Subsection 1.5 of this
Introduction and User Guide, as well as in each
individual technology section.
• All costs apply for new environmental control
technology systems as they would be installed in
new facilities. The capital cost data might be
applied to retrofit situations in which newpollution
control systems are installed at existing facilities.
However, retrofitted pollution control systems
incur a cost penalty that is not considered in the
cost data presented here. Little documented
information is available concerning cost penalties
for retrofit installations. Some retrofit costs have
been reported as a muchas70percenthigherthan
the capital investment for a comparable new
installation (1).
1.3 Cost Updating
All costs in this report are expressed in March 1980
dollars. Costs reported in the literature were updated
using cost indices and March 1980 unit prices for
labor, materials, electricity, and fuel.
Costs expressed in base year dollars may be adjusted
to dollars for another base year by applying cost
indices as shown in the following equation:
new base year cost = old base year cost x new base year index
old base year index
Capital costs from existing publications were updated
using this method. In most cases, the level of detail
available in cost references suggested that an overall
index should be applied to the total direct capital costs
rather than to individual items making up the total
direct costs. Two indices were used in this report. For
drinking water and wastewater treatment systems,
the Engineering News Record (ENR) Construction
Cost Index was used. The Chemical Engineering (CE)
Plant Cost Index was used for paniculate matter
control and flue gas desulfurization systems. Values
for these indices by year are given in Table A-5,
Appendix A.
For March 1980 these indices are:
ENR Construction Cost Index 3150
CE Plant Cost Index 253
Most major cost components of net annual operating
expense were updated individually using unit prices
for March 1980. Tabulations of unit prices are given
in Table A-3 in Appendix A. Costs for electricity and
fuel were obtained from the Monthly Energy Review
published by the Department of Energy (2). Materials'
costs were updated using the Producer Price Index for
Finished Goods. The Producer Price Index is used in
the same way as the capital cost indices discussed
above and was obtained from the Monthly Labor
Review published by the Department of Labor (3). A
basic labor rate was also obtained from this reference
and adjusted upward for fringe benefits by apply-
ing a factor.
1.4 Sources of Information and
Limitations
The costs presented in this report are derived from
cost information in existing published sources. It was
the objective of this report to prepare a cost summary
for each technology using the best documented costs
from the literature and to adjust these to a consistent
basis. It was not the objective to generate new
fundamental cost data. The primary sources of
information are recent EPA publications supplemented
by other references where necessary. System design,
system boundaries (scope), format of data presenta-
tion, terminology, reference year, and unit cost values
are variable between the different references.
Adjustments were made to bring the data into a
standard format as well as to update all costs to a
March 1980 dollar basis. In addition, for some
technologies, well documented system costs were
not available so that they had to be developed from
component costs.
A limitation of some of the cost literature is that
explicit definitions of design bases are not always
available. There is therefore an element of uncertainty
in the scope and specifications for some of the cost
data that have been used. Design bases in this report
are stated as clearly and completely as the published
information allowed. For each technology, design
criteria are described and a table of key design
parameters is presented where appropriate.
Costs in this document reflect the.'typical' or 'average'
representation of specific technologies. This restricts
the use of the data in this report to:
• Preliminary estimates used for policy planning.
• Comparison of relative costs of different technolo-
gies.
• Approximations of costs that might be incurred for a
specific application.
The costs in this report are considered to be 'order of
magnitude' with a ±50 percent margin. This is
because cost curves are drawn based on updates and
adjustments to literature costs for three or four
system capacities for each technology. Large
departures from the design basis of a technology in
this report might cause the system costs to vary by a
greater extent than this. If used as intended, however,
this document will provide a reliable source of
preliminary cost information for the technology areas
covered.
When comparing costs in this report to costs from
other references, the user should be sure the design
bases are comparable and that total capital investment,
net annual operating expenses, and unit annualized
costs are actually the costs being compared. For
example, O&M costs in many references are only part
of the net annual operating expenses as used here.
-------
1.5 Considerations When Comparing
Cost Estimates
Two important considerations affecting cost estimates
for any system are:
• design basis
• accounting methods (i.e., methodology).
These two factors probably have as much of an effect
on apparent differences in estimated costs {and
reported actual costs of completed projects) as any
other factors.
Other factors which result in differences in reported
costs are terminology and fundamental cost data
such as item prices. Sources of published cost
information do not always use the same terms to
describe costs and do not always report costs at the
same level of development. For example, in the list of
Table 1-2, the term capital cost might be used to
describe any of the items 11, 21, 31, 35, or 41
depending on individual interpretation. This problem
occurs with operating costs as well as capital costs.
Finally the differences in prices.used for capital
equipment and materials and unit prices for direct
operating cost elements such as labor and power
influence the results.
The design basis defines both the scope of a facility
and specifications for the inidividual components
comprising the facility. These determine the direct
costs for the physical plant as well as indirect costs
which typically are estimated as a percentage of
direct costs. Cost elements of operating expenses
such as labor and power requirements follow directly
from the design basis since they are related to
equipment design and operating requirements.
Again, the indirect cost elements comprising
operating expenses are dependent'on the design
basis because they are typically computed as a
percentage of both capital costs and direct operating
expenses. The prices used for various capital
equipment and operating expense items, of course,
influence the final result, but the quantities to which
the prices are applied depend on system design.
A second major reason for differences in reported
costs is costing methodology. This includes the
selection of methods for calculating various subtotals
of cost elements which, when added together, yield
the desired cost total. Sometimes every cost element
is estimated independently. Sometimes certain cost
elements are derived from others.. For estimating
capital costs, a sequence of factors is commonly
applied to purchased equipment costs or installed
equipment costs to generate a total capital requirement.
The terminology and level of summation at which the
estimating procedure is terminated determine the
cost values ultimately reported. Some insight into this
aspect of estimate preparation is found in many
literature sources (1). Similar considerations apply to
net annual operating expense.
Reported experienced costs for actual completed
facilities frequently differ from average estimated
costs used for conceptual estimating. This difference
is usually attributed to "site-specific factors."
Sometimes the differences occur due to differences
in cost accounting and the allocation of costs to
specific categories. In other cases the site-specific
factors are variables that legitimately influence costs
and are highly specific to a particular facility.
Some of these site-specific factors are due to
differences in individual waste source characteristics
which give rise to differences in treatment system
design. The design differences result in different
costs for a system, even at the same level of
performance, so that there is not always a simple
direct relationship between performance and cost.
The site-specific design which influences direct costs
combined with many indirect cost considerations
specific to a given project ultimately determines the
cost for a particular facility.
Factors that may vary with individual projects noted
by other authors as affecting costs include (4, 5):
• Competition in contractor and material supplier
markets (i.e., business climate) resulting in
unusually high or low bids and prices.
• Variations in local material and labor costs.
• Timing of construction with regard to the season of
the year, length of construction period, and
interest rates.
• Variations in conventional engineering, design,
and construction practices.
• Special considerations superimposed on normal
design requirements by local regulatory agencies.
• Cost consciousness and consideration given to
cost control during design and construction.
• Physical and climatic variations in individual site
conditions.
• Architectural features.
This discussion has highlighted some major cost-
influencing factors common to all technologies.
Additional discussion of some technology specific
variables affecting costs is provided in the individual
technology sections.
As discussed earlier, costs presented in each of the
individual technology sections that follow are based
on data from existing publications. Adjustments have
been made so that the costs conform to the format
and terminology discussed'in this section and in
Appendix A to this report. As explained above, each
treatment technology addressed may have variations
in the choice of equipment and the layout of the
equipment comprising the system which will affect
costs. In the existing cost literature for these
technologies a complete definition of design scope
and specifications is not always available. Within the
constraints of existing literature, the costs presented
here are an attempt to provide the user of this report
-------
with a thorough representation of cost estimates that
can currently be obtained for the selected technologies.
1.6 Relating Costs to Consumer Prices -
Examples
One use of this report might be to provide
information for a preliminary evaluation of cost
impacts of environmental control technologies. A
typical cost impact would be the effect on consumer
prices.
Several examples are provided here that present
costs of environmental control technologies in the
perspective of the consumer. Treatment costs are
related to a typical monthly consumer expenditure for
a commodity which would require the treatment
technology in its use or manufacture.
For drinking water and wastewater treatment in
municipal applications, an example is given relating
the cost to a typical monthly household billing for
water service. A single example is used since the
principles are the same in both of these technology
areas. For flue gas desulfurization applied to a steam
electric generating plant, the example showsthe cost
impact on the monthly electric bill. Finally, participate
matter control costs are related to the consumer price
of a building product.
Municipal wastewater treatment costs can be related
to typical household wastewater charges. Assume a
household that discharges a total of 5000 gallons a
month.* Using the unit annualized cost for any
wastewater technology discussed in the subsections
that follow, one can obtain a generalized average
monthly cost of the treatment technology to the
consumer. One multiplies the wastewater generated
in 1000s of gallons by the appropriate unit annualized
cost in dollars per 1000 gallons. Using the unit
annualized cost of $1.00 per 1000 gallons for
conventional secondary treatment plants from Figure
3-5 in this report (Section 3), the monthly charges to
cover treatment would be $13.50 in a community of
70,000 people. If an advanced wastewater treatment
plant were used, the unit annualized cost would be
$1.80/1000 gallons. Using the typical household
discussed above, the monthly charges for water
treatment by this technology would be $24.30/month.
The technology difference results in a cost increase of
80 percent. A similar example can be applied for
drinking water treatment technologies.
As another example, assume flue gas desulfurization
is used on a 500 MWe electrical generating station. A
typical household receiving electricity from this plant
uses 500 kWh/month. At an assumed electricity
price of $0.05/kWh, the total monthly bill is
$25.00/month. From Figure 5-8 in this report
{Section 5), the annualized cost per kWh (unit
annualized cost) for limestone flue gas desulfurization
on a 500 MWe steam electric generating plant is
$0.014/kWh. The impact on the typical monthly
electrical bill for these conditions would therefore be
about $7.00/month.
Where an environmental control technology is used
in a manufacturing establishment, the relationship
between the cost of control and consumer prices is
more difficult to define. Examples of such technologies
are industrial wastewater treatment, particulate
matter control, and possibly flue gas desulfurization.
If data on the manufacturing cost per unit of
consumer product and the quantity of pollutant
stream generated per unit of product were known for
any specific article or industry, the calculation of the
cost impact of the control technology on the
consumer price would be straightforward. An
industry-by-industry analysis is, however, clearly
beyond the scope of this report. But, an approximate
average relationship between control costs during
production of a particular industrial product and
consumer expenditures for that product can be
derived for illustration. An example for particulate
matter control applied to a consumer products
industry, a building-material plant.f is discussed
below.
A typical plant might produce about 400 million sq
ft/yr of product. It would produce 40,000 acfm of
particle-laden gas (air) requiring treatment with an
electrostatic precipitator to remove particulate mat-
ter. About 1700 acf of gas would be treated for each
standard unit (32 sq ft) of product produced. Referring
to Figure 4-9 {Section 4), the unit annualized cost for
an electrostatic precipitator with 99.9 percent
removal and typical precipitation characteristics
treating 40,000 acfm is $0.021/1000 acf. Multiplying
this cost by 1700 acf/standard unit of product yields a
cost of control per standard unit of product of cents
per unit. If the product sells for about $3.40 per
standard unit, the particulate matter control
technology adds about 1.1 percent to the price the
consumer pays in this example. The same concept
can be applied to any other manufacturing industry,
for any environmental control technology.
These illustrations are given only to provide
perspective on the magnitude of impacts that
environmental control technologies may have, and
are only approximations. A detailed analysis is
beyond the scope of this report. The examples are.
•This is a rough estimate for a household of three people. In this report,
system design capacity assumed a design value of 150 gallons per capita
per day for wastewater and 200 gallons per capita per day for drinking
water. Actual usage in a given household will not necessarily reflect these
design values.
f Product deta ils are not given so as to avoid any chance of misrepresentation
of environmental control cost impacts for a specific product. A more
detailed analysis would be needed to confirm production data, prices, and
cost impacts for the actual industry.
-------
however, an indication of how the environmental
technology control costs can be reflected in consumer
prices, and how information in this report can be used
in estimating effects on prices.
References - Section 1
1. Uhl, V.W. A Standard Procedure for Cost Analysis
of Pollution Control Operations. Vol. I. User Guide,
EPA-600/8-79-018a (PB80-108038*). Vol. II.
Appendices, EPA-600/8-79-018b (PB80-108046*).
U.S. Environmental Protection Agency, Industrial
Environmental Research Laboratory, Research
Triangle Park, NC, June 1979.
2. U.S. Department of Energy. Monthly Energy
Review. DOE/EIA 0035/05(80).
3. U.S. Department of Labor. Monthly Labor Review.,
103(6): June 1980.
4. Dames and Moore. Construction Costs for
Municipal Wastewater Treatment Plants: 1973-
1977. EPA-430/9-77-013 (PB282436*). U.S.
Environmental Protection Agency, Office of Water
Program Operations, January 1978.
5. Patterson, W.L., and R.F. Banker. Estimating Costs
and Manpower Requirements for Conventional
Wastewater Treatment Facilities. Project No.
17090 DAN, Contract No. 14-12-462, PB211132*.
U.S. Environmental Protection Agency, October
1971.
•Available for purchase from the National Technical Information Service,
5285 Port Royal Road, Springfield, VA 22161.
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Section 2
Drinking Water Treatment
In 1975, some 177 million people were served by the
approximately 40,000 community water systems in
the United States (1}. In addition to community water
systems, numerous individual systems exist including
individual households, and systems such as those at
resorts or other public-access facilities. Most water
systems serve a population of 100 to 10,000 people
(1). Assuming a system design basis of 200 gallons
per day (gpd) per capita, these systems are in the size
range of about 20,000 gpd to 2.0 million gallons per
day (mgd).
The raw water treated in these systems is either
surface water from lakes and rivers or underground
water. The purpose of these treatment systems is to
make the water palatable, in terms of clarity, taste,
and odor, and safe for human consumption.
Treatment methods vary according to the quality of
each individual water source.
Some contaminants occur naturally, some arise from
domestic, industrial and agricultural activities, and
some are formed during traditional water treatment.
For example, trihalomethanes can form during
conventional chlorine disinfection of drinking water
when chlorine reacts with some organic substances.
The ionic species and organic compounds of interest
in drinking water are usually expressed in concentra-
tion units of milligrams per liter (mg/l) or micrograms
per liter (//g/l). Turbidity, caused by suspended solids,
is usually expressed in turbidity units (TU) which are
defined for a specific turbidity test method.
New knowledge of health effects and increasingly
sensitive analytical chemistry procedures have
enhanced recognition of potential long term health
hazards due to certain water contaminants. This
consideration, combined with increasing demands of
population growth on available water supplies,
requires that continued attention be given to drinking
water treatment for upgrading raw water quality. The
continued increase in demand relative to supply will
likely increase the use of treated and recycled
wastewater to meet drinking water needs in the
future. More sophisticated methods and extensive
use of these methods for drinking water treatment will
be required.
A key legislative milestone was the Safe Drinking
Water Act of 1974 (Public Law 93-523) and the
promulgation of Interim Primary Drinking Water
Regulations under that Act. This act focused the
attention of the public and health and environmental
professionals on the quality of drinking water
supplies and resulted in drinking water quality
standards to protect the consumer. The Act defines
contaminants, maximum concentration levels,
primary drinking water regulations, secondary
drinking water regulations, public water supplies and
systems, and other items. A set of enforceable health-
related regulations and a set of non-enforceable
a esthetic-related guidelines for drinking water were
established. These regulations and subsequent
revisions in 1978 set maximum levels for various
water contaminants including potentially toxic ionic
species, certain organic chemical compounds, and
suspended solids which cause turbidity. Other
materials that must continue to b'e removed include
pathogenic microorganisms and substances which
cause taste, odor, and color. Table 2-1 lists the
permissible concentrations of various materials as
set forth under the Act (2).
These regulations, which require greater removal of
contaminants than is now common practice,
increased the costs of treatment. The capital
investment and annual costs of those treatment
technologies required to meet the new standards are
summarized in this section.
Because the cost of a water treatment system per
unit of water produced decreases as plant size
increases, the economic impact of increased water
treatment on small systems is greater on a unit basis
than on large systems. However, the total sums
required for capital investment and operating
requirements become large as system sizes increase.
Policy planning must therefore address the cost
implications of both large unit revenue requirements
(higher customer costs) for small systems and
investment capital availability for large systems.
Finally, the cost impacts resulting from new
treatment requirements must be viewed in the
context of the total costs of the water supply system.
A charge rate profile for typical water supply systems
was presented by Clark and Stevie (3). Table 2-2
presents the percentage contribution of each
component of the overall water supply system, as
derived from the data given by Clark. The average
8
-------
Table 2-1. Drinking Water Contaminant Levels Based on Safe
Drinking Water Act (2)
Maximum contaminant level
Contaminant (MCL)
Table 2-2. Charge Rate Profile for Typical Total Drinking Wa-
ter System Costs Based on Survey Data (3)
Percentage of total
Arsenic, mg/l
Barium, mg/l
Cadmium, mg/l
Chromium, mg/l
Lead, mg/l
Mercury, mg/l
Nitrate (as N), mg/l
Selenium, mg/l
Silver, mg/l
Endrin mg/l
Lindane mg/l
Toxaphene mg/l
2,4-D, mg/l
2, 4, 5 - TP (Silvex), mg/l
Methoxychlor, mg/l
Alpha emitters:
Radium - 226, pCi/l
Radium - 228, pCi/l
Gross alpha activity (excluding
radon and uranium}, pCi/l
Beta and photon emitters:3
Tritium, pCi/l
Strontium, pCi/l
Turbidity, turbidity unitb
Fluoride, mg/lc
Trihalomethanes and organic
chemicals,0
0.05
1.0
0.01
0.05
0.05
0.002
10.0
0.01
0.05
0.002
0.004
0.005
0.1
0.01
0.1
5
5
15
20
1
1.4-2.4
aBased on a water intake of 2 liters/day. If gross beta particle activi-
ty exceeds 50 pCi/l, other nuclides should be identified and
quantified on the basis of a 2-liter/day intake.
One turbidity unit based on a monthly average. Up to 5 turbidity
units may be allowed for the monthly average if it can be
demonstrated that no interference occurs with disinfection or
microbiological determinations.
°Depends on air temperature.
"On February 9, 1978, the EPA proposed to amend the National
Interim Primary Drinking Water Regulations by adding
regulations for organic chemical contaminants in drinking water.
The proposed amendment consisted of two parts:
1. An MCL of 0.10 mg/l (100 parts per billion) for total
trihalomethanes (TTHM), including chloroform.
2. A treatment technique recommending the use of granular
activated carbon for the control of synthetic organic
chemicals. Three criteria that the granular activated carbon
must achieve are: an effluent limitation of 0.5/yg/l for low
molecular weight halogenated organics (excluding trihalo-
methanes), a limit of 0.5 mg/l for effluent total organic
carbon concentration when fresh activated carbon is used,
and the removal of at least 50 percent influent total organic
carbon when fresh activated carbon is used.
Part 1 was promulgated November 29, 1979. Part 2 has been
cancelled.
large system capacity was 85 mgd, and the average
small system was 5 mgd. If the costs reflected in the
charge rate presented by Clark are'updated to March
1980, the typical total system charge rate is
$0.57/1000 gal for large systems and $1.20/1000
gal for small systems. If it is assumed that user rates
are approximately 20 percent greater than the system
charge rates, these figures provide an estimate of
typical user total charge rates.
It must be emphasized that these costs are for
existing systems ratherthan new facilities; therefore.
System component
Support services
Acquisition
Treatment
Distribution
Interest on debt
Large system
(85 mgd)
24.4
13.4
11.8
29.0
21.4
Small system
(5 mgd)
17.6
15.1
10.3
41.9
15.1
costs included for capital-related charges are based
on historical values for invested capital. Because the
water systems in the study were built 30 to 40years
ago, the capital charge components in the total are far
lower than would be encountered if comparable
facilities were built today. On a historical basis, the
cost of the treatment step is approximately 11 percent
of the total cost of supplying drinking water. In
considering upgrading water supply systems to
improve water quality, however, a main focus of the
upgrading will be on the treatment technologies.
Where an acquisition and distribution system is
already in place, a new treatment facility might be
built to upgrade or replace the existing treatment
facility. In such a case, only the treatment portion of
the water cost would have to be substantially
changed. Obviously, its portion of the total system
cost would increase from the 11 percent discussed
above.
Based on the considerations discussed above, only
treatment technologies are considered in this report.
For some water systems, these treatment technologies
might be necessary to meet water quality requirements
under the Safe Drinking Water Act. These technologies
include both total treatment systems as well as
individual single processes which could be added at
existing total treatment plants or incorporated into
new total treatment plants. The single processes
include methods for disinfection and the removal of
organic chemical compounds.
The total treatment systems comprising several
process steps include conventional filtration, direct
filtration, and lime softening filtration plants. These
filtration plants primarily reduce the concentration of
both dissolved inorganic materials and suspended
solids present in the raw water. Most of the toxic
substances identified in the Safe Drinking Water Act
are probably present as dissolved solids. Suspended
solids cause turbidity and harbor harmful microbes.
Direct filtration differs from conventional filtration
primarily by the absence of the sedimentation step.
Chemicals such as alum or iron salts are added to
precipitate suspended solids directly in the filters. In
lime softening plants the addition of lime contributes
not only to suspended solids removal but also to the
removal of some dissolved substances. These
-------
dissolved substances become insoluble upon the
addition of lime and are removed by sedimentation
and filtration. Lime is used when lower levels of
dissolved minerals must be achieved than can be
achieved using alum or iron salts.
Disinfection methods include chlorinatton and
treatment with other disinfectants. In some water
systems where raw water quality is high, chlorine
disinfection may be the sole treatment used.
Alternative disinfectants to chlorine include chlorine
dioxide, ozone, and ammonia used in combination
with chlorine. Granular activated carbon treatment
and aeration are technologies used specifically for
the removal of organic compounds. Disinfection and
organic removal methods can be add-on technologies
to any of the total treatment processes.
In the individual technology sections that follow,
cost curves are presented for total capital investment,
net annual operating expenses, and unitannualized
cost as a function of system design capacity in
millions of gallons per day. Brief process descriptions,
a design basisfor the costs presented, and a summary
of major variables affecting costs are also presented.
2.1 Filtration Treatment Plants
2.1.1 Description
There are three different kinds of filtration treatment
plants:
• Conventional filtration.
• Direct filtration.
• Lime softening (with conventional filtration).
These three kinds of plants share several common
process steps. Direct filtration and lime softening are
essentially variations of a conventional filtration
plant. These plants all remove turbidity-causing
suspended solids and some mineral matter from
drinking water supplies.
Conventional Filtration (2,4,5)
A conventional filtration plant for drinking water
treatment removes suspended solids and some
dissolved mineral matter. It also destroys harmful
microorganisms in the water supply. A typical
conventional filtration plant is shown conceptually in
Figure 2-1.
Raw water is pumped to a rapid mix tank in which
chemical (e.g., alum and polymer) solutions are added
to enhance flocculation. A flocculation vessel allows
sufficient time for the suspended solids to aggregate
into the larger particles, or floes, which are more
efficiently removed by the downstream treatment
steps (sedimentation and filtration).
Sedimentation basins are either circular or rectangular
vessels in which the floes are allowed to settle. The
basins can be concrete or steel, depending on size. A
waste sludge of solids and water is removed by
Figure 2-1. Conventional filtration system for drinking water treatment.
Raw
Water-
Rapid Mix &
Flocculation
Vessels
Sludge to Disposal
Spent Backwash
Water to Disposal
Alum and
Chemical | Polymer
Addition • Solutions
Intermittent
Backwash Supply
Water
System Boundary
Finished
Water to
Distri-
bution
System
10
-------
discharge to a municipal sewer or hauled to a landfill
for disposal. Clarified water then flows to the filter
unit.
The filters consist of one or more steel or concrete
vessels containing granular materials such as graded
sands, anthracite, and garnet. Solids are strained
from the water as it passes through the filters. When
the pressure drop through the filters becomes great
enough due to accumulated solids, a backwash
stream of filtered water passes through the units in
reverse flow to clean the solids from thef ilter bed. The
spent backwash stream is sent to a sewer.
Backwashing is intermittent; the backwash cycle
depends on the character and concentration of solids
in the water, as well as on filter design parameters
such as application rate and filter medium particle
.size.
Filtered water is disinfected with chlorine and stored.
From storage it is pumped to the water supply
distribution system.
Direct Filtration (2,4,5)
A direct filtration plant is essentially the same as the
conventional filtration plant shown in Figure 2-1
except the sedimentation step is deleted.
Direct filtration is applicable to any drinking water
supply where suspended solids levels are sufficiently
low to result in a reasonable backwash cycle on the
filter units. Unlike conventional filtration plants, there
is an upper limit to the influent suspended solids
concentration that can be tolerated. This upper limit
must be determined by testing. Above such a level,
conventional treatment procedures or sedimentation
prior to filtration are required.
Lime Softening (2,4,5)
The major features of a lime softening plant are also
essentially the same as those for a conventional
filtration plant, except that lime is substituted for
other chemicals and a recarbonation step is added
after sedimentation. A lime softening plant is typically
used to treat raw water with a higher concentration of
dissolved minerals, such as calcium and magnesium,
than can be treated in a conventional or direct
filtration plant. In the context of the Safe Drinking
Water Act, a lime softening plant can also be expected
to achieve a greater removal of toxic mineral
substances. For example, a lime softening plant
operating in a pH range of 8.5 to 11 can reduce
cadmium concentrations from 0.5 mg/l to 0.01 mg/l.
To achieve the same cadmium concentration in the
treated effluent, a conventional filtration plant using
alum or iron salts can only accommodate a cadmium
concentration up to 0.1 mg/l of cadmium in the raw
water (2). The choice of overall treatment process
therefore depends on individual raw water character-
istics.
Lime can be added directly to the influent raw water
as a solid, or as a pre-mixed water slurry. If a slurry is
used, the solid lime is usually purchased and the
slurry prepared on-site. Details of lime feed systems
are described elsewhere (6, 7).
Recarbonation is the addition of gaseous carbon
dioxide (C02) to the lime-treated water to neutralize
excess alkalinity resulting from lime addition.
Gaseous COs may be obtained from liquid COg stored
onsite, submerged burners, or stack gas compressed
through a sparger system. The choice of carbonation
method depends on site specific considerations.
2.1.2 Design Basis and Costs (2,4,5)
The design basis in this report for conventional
filtration plant costs includes the following major
process modules and design parameters:
Raw water pumping.
Chemical addition.
Rapid mix/Flocculation.
Sedimentation.
Filtration.
Disinfection.
Finished water storage.
Finished water pumping.
Sludge disposal.
As stated in the process descriptions, there is no sedi-
mentation step in direct filtration. The filtration
directly follows the rapid mix and flocculation step.
The chemical feed system consists of chemical
storage and metering pump facilities. The rapid mix
tank and flocculation vessel is one vessel partitioned
into separate sections. Filtration units are gravity flow
steel or concrete vessels. The clear well is a concrete
storage basin. System design parameters depend on
raw water quality and the finished water quality
required.
The major process modules for the lime softening
plant are very similar to those for conventional
filtration, except for modifications to the chemical
feed system and addition of recarbonation equipment
Recarbonation basins are reinforced concrete, and
submerged natural gas burners are used for the C02
source in the system considered here based on the
configuration and costs in Reference 2.
The plant cases represented here include chlorine
disinfection, the usual procedure in conventional
plants. Alternative disinfectants such as chlorine
dioxide, ozone, or ammonia added with chlorine can
also be used. The disinfection systems for each of
these alternatives are discussed in Section 2.2
Total capital investment for conventional filtration,
direct filtration, and lime softening is presented in
Figure 2-2. Net annual operating expenses are shown
in Figure 2-3. Figure 2-4 shows corresponding unit
annualized costs.
-------
Figure 2-2. Filtration plants for drinking water treatment
- Total capital investment (March, 1980 dollars).
Conventional Filtration Plant — • "-•- •-
Direct Filtration Plant — — — — -
Lime Softening Plant -.—.._..
Packaged Conventional Plant
m
UJ _™
Q. O
< =
O
10
1.0
0.1
0
- 1 1 1 1 1 1 1 I
-
: ..**"
»*
, . , 1,,,,
I 1 1 1 M I 1
x^
1 1 I (MIL
X -
, , , L.M
1 1.0 10 10
0.5
1_
SYSTEM CAPACITY, mgd
5 50
500
POPULATION SERVED, thousands
Figure 2-3. Filtration plants for drinking water treatment
• Net annual operating expenses (March, 1980
dollars).
Conventional Filtration Plant ^—^^—
Direct Filtration Plant
Lime Softening Plant ••
Packaged Conventional Plant
10
0.1
0.5
1.0 10
SYSTEM CAPACITY, mgd
50
100
500
POPULATION SERVED, thousands
12
Figure 2-4. Filtration plants for drinking water treatment
• Unit annualized cost (March, 1980 dollars).
Conventional Filtration Plant
Direct Filtration Plant
Lime Softening Plant
Packaged Conventional Plant
300
1.0 10
SYSTEM CAPACITY, mgd
0.5
I
50
I
100
500
POPULATION SERVED, thousands
Also provided in the figures are costs for packaged
conventional filtration plants which can be used for
small treatment systems (5). These plants would have
the same unit processes as their larger field-
constructed counterparts but would be primarily
shop fabricated and brought to the field for final
installation.
2.1.3 Major Variables Affecting Costs
For any of the filtration plants discussed here, the
large number of process steps and associated
variables result in many possible combinations of
equipment sizes and specifications. These factors
largely depend on site specific requirements with raw
water quality the primary variable. A complete
analysis of the cost impacts of changes in design is
beyond the scope of this report. However, examination
of the cost profile for capital investment reveals that
the greatest portion of the investment is in the filter
portion of the plant. Therefore, changes in design
requirements for the filters have a very large impact
on total plant capital costs. For lime softening plants
lime dosage is an important variable. Also, as can be
seen from the figures, costs for shop fabricated
packaged plants are less than for field constructed
plants of similar size. Operating expenses, specifically
electricity costs for pumping, are affected by
frequency of backwashing in the filtration unit which
-------
Figure 2-5. Chlorination system for drinking water treatment.
Chlorine
Storage
and
Handling
System Boundary
Water Sidestrearn"
toEductorin
Chlorinator
Chlorine
Solution
to Point of
Application .
Mainline Water Flow,
in turn depends on raw water suspended solids
levels.
2.2 Disinfection
Disinfection destroys microbes harmful to human
health. Chlorine is the most commonly used
disinfectant. Because chlorine addition can lead to
the formation of trihalomethanes {potential carcino-
gens), use of the alternative disinfectants chlorine
dioxide, ozone, and ammonia in combination with
chlorine has been considered (8). The last alternative
results in the formation of chloramines which
disinfect while obviating the formation of trihalome-
thanes.
2.2.7 Chlorine
Description (4)
Chlorine may be added directly to the water as
chlorine gas or indirectly as a sodium hypochlorite
solution. Only direct feed chlorination is discussed in
this report because it is more widely used.
The major features of a chlorination system are
shown in Figure 2-5. The system includes, both
chlorine storage and feed equipment. The chlorinator
consists of a metering device and an educator in
which the chlorine mixes with a smalt sidestream
taken from the main water line. After passing through
the chlorinator, the sidestream rejoins the main flow,
delivering the disinfectant to the water supply.
For small systems that require chlorine feed rates at
100 Ib/day or less, chlorine is stored in standard 150-
Ib cylinders. Chlorine for larger systems with feed
rates up to 2000 Ib/day is stored in 1 -ton cylinders.
For systems larger than 2000 Ib/day, chlorine is
stored in: 1-ton cylinders, on-site tanks supplied by
rail delivery, or rail cars kept on a rail siding.
Design Basis and Costs (2,4,5)
Each installation is assumed to have a duplicate
standby chlorinator, injector pumps on the water
sidestream fed to the chlorinator, housing for the
chlorinator, and a 30-day chlorine storage capacity.
Cylinder storage is assumed. Evaporators are
assumed for systems requiring chlorination feed
rates of greater than 2000 Ib/day; chlorine residual
analyzers are assumed for systems where chlorine
flow rates are greater than 1000 Ib/day; cylinder
hoists are assumed for systems where chlorine feed
rates are less than 100 Ib/day.
Typical piping costs are included, although
individual site layouts will cause these to vary.
Operating requirements include labor for operation
and maintenance of the metering equipment, and
activities associated with storage. Material require-
ments are for maintenance. Power requirements are
for pumping, mixing, and building heating, lighting,
and ventilation.
Total capital investment requirements for chlorination
systems are presented in Figure 2-6. Total capital
investment is plotted against water plant flow rate in
millions of gallons per day. The two curves
correspond to chlorine feed dosage rates of 1 mg/l
and 5 mg/l. The dosage rate required depends on the
disinfection requirements of the specific water supply
being treated. Below plant capacities of 0.1 mgd, the
total capital investments is essentially at about $7,600
(March 1980 dollars) (5).
Net annual operating expenses are plotted against
water plant flow rate in millions of gallons per day in
Figure 2-7. Unit annualized cost is shown in Figure 2-
8. The two curves again reflect different chlorine
dosage levels.
Major Variables Affecting Costs
The cost curves indicate clearly the effect of dosage
on costs for chlorination systems. Dosage in turn
depends on individual water characteristics. An
important variable in chlorination is pH as it affects
the chemistry of solution and hence the dosage
required to achieve a given disinfection effectiveness
(8). The type of storage system in larger facilities, tank
or railcar siding storage compared to the cylinder
storage used here, for example, and individual plant
layout items such as differing lengths of piping runs
also affect costs.
13
-------
Rgure 2-6. Chlorination system for drinking water
treatment • Total capital investment (March,
1980 dollars).
High Chlorine Dosage, 5 mg/l
Low Chlorine Dosage, 1 mg/l
0.1
0.5
1.0 10
SYSTEM CAPACITY, mgd
5 50
1 I
100
500
I
POPULATION SERVED, thousands
Figure 2-8. Chlorination system for drinking water
treatment • Unit annualized cost {March, 1980
dollars).
High Chlorine Dosage, 5 mg/l - —
Low Chlorine Dosage, 1 mg/l - — — — -
0.5
1.0 10
SYSTEM CAPACITY, mgd
5 50
I I
100
500
POPULATION SERVED, thousands
Rgure 2-7. Chlorination system for drinking water
treatment • Net annual operating expenses
(March, 1980 dollars).
High Chlorine Dosage, 5 mg/l
Low Chlorine Dosage, 1 mg/l
0.5
L_
1.0 10
SYSTEM CAPACITY, mgd
5 50
1 i
100
500
POPULATION SERVED, thousands
14
2.2.2 Chlorine Dioxide
Description (4)
Chlorine dioxide is used for disinfection of drinking
water in the same manner as chlorine. In fact, the
feed equipment for chlorine dioxide is essentially the
same as that for chlorine. Rather than obtaining
chlorine dioxide from storage containers, as is done
with chlorine, however, chlorine dioxide gas is
commonly generated on-site by mixing a high-
strength chlorine solution with a high-strength
acidified sodium chlorite solution. These solutions
are fed to a mixing chamber referred to as a
generator. The generator is a plastic cylinder
containing a loose porcelain fill material. Detention
time in the generator is about 2 minutes or less. The
gas evolving from solution then feeds to a device
identical to the chlorinator discussed for chlorine
treatment in Section 2.2.1.
A typical schematic of a chlorine dioxide system is
shown in Figure 2-9. The sodium chlorite system
consists of a polyethylene mix tank and a metering
pump. The sodium chlorite is stored in bags on
pallets.
Design Basis and Costs (2,4,5)
To generate 1 Ib of chlorine dioxide, a feed ratio of
1.68 Ib chlorine to 1.68 Ib sodium chlorite is assumed.
-------
Figure 2-9. Chlorine dioxide system for drinking water treatment.
'"I
Dry
Sodium
Chlorite
Sodium
Chlorite
Solution
Sodium
Chlorite
Solution
Dry Sodium
Chlorite.Storage
and Handling
Sodium Chlorite
Splution
Mix Tank
Metering
Pumps
Chlorine
Dioxide
Generator
Chlorine
Liquid
Chlorine
Storage and
Handling
Chlorine
Evaporator
Chlorine
Solution
System Boundary
Mainline Water Flow
Intermittent
Water Sidestream
to Sodium Chlorite
Mix Tank
Continuous
Water Sidestream
To Eductor in
Chlorinator
Chlorine
Dioxide
Solution
to Point of
Application
In order to estimate costs the necessary equipment
has been added to the design scope of the chlorine
systems already discussed in the preceding section.
Costs for bag storage of sodium chlorite on pallets are
assumed to be negligible in the context of the total
system and were not included in the costs in
References 2, 4, and 5.
Operating requirements include labor for the chlorine
system as well as labor for preparation of the
hypochlorite solution and for maintenance of mixing
and metering equipment. Material requirements are
for maintenance of all system components. Power
requirements are for pumping, mixing, and building
heating, lighting, and ventilation.
Capital costs for chlorine dioxide systems are
presented in Figure 2-10 expressed as total capital
investment plotted against water system flow rate in
millions of gallons per day. The two curves
correspond to chlorine dioxide dosage rates of 1 mg/l
and 5 mg/l. The dosage rate required depends on the
disinfection requirements of the specific water supply
being treated.
Figure 2-11 presents net annual operating expenses
plotted against water system flow rate in millions of
gallons per day. Again, the two curves correspond to
different chlorine dioxide dosage levels. Upit
annualized costs are shown in Figure 2-12.
Major Variables Affecting Costs
The cost curves indicate clearly the effect of dosage
on costs for chlorine dioxide systems. Individual plant
Figure 2-10. Chlorine dioxide system for drinking water
treatment - Total capital investment (March,
1980 dollars).
High Chlorine Dioxide Dosage, 5 mg/l ' •
Low Chlorine Dioxide Dosage, 1 mg/l
10 P i—i i j 11 ni 1—f i jinn 1—r i |iiu
1.0 10
SYSTEM CAPACITY, mgd
0.5
50
100
500
I
POPULATION SERVED, thousands
15
-------
Figure 2-11. Chlorine dioxide system for drinking water
treatment - Net annual operating expenses
(March, 1980 dollars).
High Chlorine Dioxide Dosage, 5 mg/l
Low Chlorine Dioxide Dosage, 1 mg/l — — — — -
0.5
i
1.0 10
SYSTEM CAPACITY, mgd
5 50
i i
100
500
POPULATION SERVED, thousands
Figure 2-12. Chlorine dioxide system for drinking water
treatment - Unit annualized cost (March, 1980
dollars).
High Chlorine Dosage, 5 mg/l —
Low Chlorine Dosage, 1 mg/l - — — — —
o
o«
N a
^ *-
^3 w
< Q.
30
25
20
15
10
-\ \ ' ' 1 ""
" \ \
I \ \
— \ \
: \ \
\ \
\ \
\
: \
\
\
: \
\
\
-
-ill Inn
i i i [ ii ii
\
x
x
\^
^^.
\
X
1 1 1 1 11 II
1 I 1 | "ML
-
_
—
_
-
-
-
-
—
" 1
-
-
i i i 1 n if
1.0 10
SYSTEM CAPACITY, mgd
0.5
50
100
500
POPULATION SERVED., thousands
16
layout and the storage system selected for the
required chlorine starting material can affect costs
significantly. Considerations similar to those
discussed for chlorination systems apply for chlorine
dioxide also.
2.2.3 Ozone
Description (4)
Ozone is generated on-site by passing air or oxygen
through an electric arc. Ozone generators are
standard items manufactured by vendors. At ozone
generation rates less than approximately 100 Ib/day
air is more economical than oxygen. Pure oxygen
storage costs can be justified at higher ozone
generation rates. A block diagram of an ozone
disinfection system is shown in Figure 2-13.
Ozone from the generator feeds to the dissolver
chamber where it is well mixed with a sidestream of
the water being treated. The solution then flows to a
contact chamber where it mixes with the mainstream
waterflow. The required contact time is typically
about 15 minutes in the contact chamber.
Design Basis and Costs (4,5)
System costs include costs for the components
shown in Figure 2-13, as well as the costs of
equipment for off-gas recycling, electrical, instrumen-
tation, safety, and monitoring requirements. The
ozone contact chamber is a covered reinforced
concrete structure, 18 ft deep with a length-to-width
ratio of 2:1. The chamber contains partitions to
ensure good flow distribution.
For systems that require 100 Ib/day or less of ozone,
air is the oxygen source. Systems with an ozone
requirement greater than 100 Ib/day use oxygen and
include oxygen storage and transfer equipment. In
the typical system, all equipment is housed except
oxygen equipment which is located outside the
building on a concrete slab.
Operating requirements are similar to those
discussed for chlorine and chlorine dioxide. Electrical
power costs will be higher because electricity is used
to generate ozone as well as for pumping and building
requirements.
Total capital investment for ozone systems is shown
in Figure 2-14, net annual operating expenses in
Figure 2-15, and unit annualized cost in Figure 2-16.
The two curves in each figure correspond to different
dosage levels. The dosage level depends on the ozone
demand of the specific water stream being treated.
Major Variables Affecting Costs
Dosage, which in turn depends on the characteristics
of the individual water supply, has a pronounced
effect on the cost of an ozonation system. It affects
storage and feed equipment sizing, and electricity
-------
Figure 2-13. Ozonation system for drinking water treatment.
Air or
Oxygen*
Mainline Water Flow
Off-Gas Recycle
Dry,
Filtered
Air or
Oxygen
System Boundary
Water
Sidestream
to Dissolver
Ozone
Solution
to Contact
Chamber
"If oxygen is used the system will include oxygen storage equipment. Oxygen would be
used only for ozone requirements greater than 100 Ib/day.
Figure 2-14. Ozonation system for drinking water treatment
- Total capital investment (March, 1980 dollars).
High Ozone Dosage, 5 mg/l •
Low Ozone Dosage, 1 mg/l -— — — -
Figure 2-15. Ozonation system for drinking water treatment
- Net annual operating expenses (March, 1980
dollars).
High Ozone Dosage, 5 mg/l
Low Ozone Dosage, 1 mg/l — — — — -
10 c
!Z c
Q. O
< =
1.0
0.1.
.01
0.1
0.5
1.0 10
SYSTEM CAPACITY, mgd
50
S-
100
500
POPULATION SERVED, thousands
Q- 2?
XQ)
^Kl
UJ •"
•TO
%2
O o
IU
1.0
0.1
•01o
0
I I I 1 1 1 1 1
—
i ii 1 1 1 1
ff
i i i I ii n
1 1 1 (Mil.
^S J
\ i i Ii 1 11
.1 1.0 10 1C
SYSTEM CAPACITY, mgd
55 50 50
i
POPULATION SERVED, thousands
17
-------
Figure 2-16. Ozonation system for drinking water treatment
- Unit annualized cost (March, 1980 dollars).
High Ozone Dosage, 5 mg/l ^__^
Low Ozone Dosage, 1 mg/l • —
120
1.0 10
SYSTEM CAPACITY, mgd
0.5
50
100
500
POPULATION SERVED, thousands
requirements. System design, with the choice of
either an air or oxygen feed, also influences costs.
2.2.4 Chloramination
Description
In chloramination, chlorine and ammonia are mixed
together in water solution to form chloramines which
act as a disinfectant. Chloramination does not form
trihalomethanes as does direct chlorination.
Figure 2-17 is a schematic of a chloramination
system. The system is comprised of a direct
chlorination system with the addition of an ammonia
feed system.
A system can be designed for either aqueous
ammonia or anhydrous ammonia feed. Aqueous
ammonia is usually available near large cities and is
used more in larger facilities than anhydrous
ammonia.
Design Basis and Costs (4)
The anhydrous ammonia system provides a 10-day
storage capacity for bulk ammonia. The storage
system includes the tank and its supports, a weigh
scale, an air padding system for the tanks, and all
gauges, pipes, and valves. The feed portion of the
system consists of an evaporator and flow metering
equipment.
The aqueous ammonia system also provides fora 10-
day storage capacity. The storage system includes a
Figure 2-17. Chloramination system for drinking water treatment.
Ammonia*
Storage
and Handling
Aqueous
Ammonia
Solution
Ammonia Solution to Point of Application
Anhydrous |
Ammonia |
Liquid
System Boundary
Ammonia Gas to Point of Application
+_IJ
Chlorine
Storage
and Handling
Mainline Water Flow,
Continuous Water
Sidestream to Eductor
in Chlorinator
*One of the two ammonia systems shown would be selected for a given installation.'
18
-------
horizontal pressure vessel, supports, piping and
valves, and a metering pump.
Costs are given only for the ammonia components of a
chlorimination system. This technology would most
likely be used to convert a plant with an existing
chlorination system to chloramination. It is less likely
that plants would be specifically designed to use
chloramination. For those cases in which the
ammonia and chlorine systems are constructed at the
same time, however, the chlorination costs discussed
earlier in Section 2.2.1 can be added to costs for the
ammonia system to derive a total chloramination
system cost.
Total capital investment is presented in Figure 2-18,
net annual operating expenses in Figure 2-19, and
unit annualized cost in Figure 2-20. The multiple
curves shown correspond to different dosage
requirements and the form of ammonia used. As the
curves show, costs are relatively constant below a
minimum system size.
Major Variables Affecting Costs
The most significant design variable which affects
costs is whether anhydrous or aqueous ammonia is
Figure 2-18. Ammonia feed system for drinking water
treatment by chloramination • Total capital
investment (March, 1980 dollars).
Anhydrous Ammonia
High Ammonia Dosage, 1.7 mg/l
Low Ammonia Dosage, 0.3 mg/l
Aqueous Ammonia
High Ammonia Dosage, 1.7 mg/l
Low Ammonia Dosage, 0.3 mg/l
1.0
z
HI
QJ JO
0.1
ES
D. O
< =
O e
E -01
O
.001
0.1 1.0 10
SYSTEM CAPACITY, mgd
0.5 5 50
I i i
100
500
i
Figure 2-19. Ammonia feed system for drinking water
treatment by chloramination • Net annual
operating expenses (March, 1980 dollars).
Anhydrous Ammonia
High Ammonia Dosage, 1.7 mg/l
Low Ammonia Dosage, 0.3 mg/l
Aqueous Ammonia
High Ammonia Dosage, 1.7 mg/l . — . — .—
Low Ammonia Dosage" 0.3 mg/l
LLJ
CO
z
m !s
x|
LU •*•
i!
5 1
tr o
- *_
O o
uu
0.1
0.5
I
1.0 10
SYSTEM CAPACITY, mgd
50
i
100
500
i
POPULATION SERVED, thousands
POPULATION SERVED, thousands
used. As mentioned earlier this can be partly
influenced by geographical location and the relative
availability of anhydrous and aqueous ammonia.
Dosage is another significant variable which depends
on individual water characteristics as it did with other
disinfectants.
2.3 Granular Activated Carbon
Treatment
Description
Granular activated carbon can be used in a drinking
water treatment plant to remove dissolved organic
compounds some of which may be present in low
concentrations. These compounds may be present in
the raw makeup water or they may be formed as a
result of drinking water chlorination (e.g., trihalome-
thanes). Carbon treatment can be used either before
or after chlorination to remove either precursors or
contaminants themselves that might form.
A typical complete granular activated carbon
treatment system is illustrated schematically in
Figure 2-21. Water may enter the system after
19
-------
Figure 2-20. Ammonia feed system for drinking water
treatment by chloramination - Unit annualized
cost (March, 1980 dollars).
Aqueous Ammonia
High Ammonia Dosage, 1.7 mg/l -^——
Low Ammonia Dosage, 0.3 mg/l
Anhydrous Ammonia
High Ammonia Dosage, 1.7 mg/l
Low Ammonia Dosage, 0.3 mg/l •
100
0.1
0.5
1.0 10 100
SYSTEM CAPACITY, mgd
5 50 500
I I I
POPULATION SERVED, thousands
treatment to remove suspended solids and/or after
lime softening used to remove mineral substances in
one of the treatment plants already discussed in
Section 2.1. It then flows by gravity or pressure
through stationary beds of activated carbon contained
in two or more steel or concrete adsorption vessels
(contactors).
Packaged plants with pressure flow steel contactors
maybe used in small facilities with system capacities
of less than 1 mgd. Plants treating more than 1 mgd
are usually field constructed because mechanical,
structural, and transportation constraints limit the
size of portable units. These plants can use either
pressure flow steel contactors or gravity flow
concrete or steel contactors. In larger facilities above
approximately 10 mgd, gravity flow concrete or steel
contactors are generally used. Concrete contactors
are usually more cost effective in large installations
because large volume steel contactors are expensive,
as are the large numbers of smaller steel vessels that
would be required. Contactors are available in
standard sizes, and multiple contactors operating in
parallel flow are used to achieve a given plant
capacity.
Periodically, typically every several months, the
carbon must be removed from the contactors and
regenerated to restore its ability to remove
contaminants from water. This is accomplished by
burning off the contaminants in a regeneration
furnace. A granular activated carbon system contains
at least two contactors so that they can be alternately
Figure 2-21. Granular activated carbon system for drinking water treatment.
Water from
Filtration
Make-Up Spent ' '
Carbon Carbon
i
In-Plant 1
'^•^•^J
System Boundary
Back
V
Carbon
Contactc
System
wash
Vater
•
Regenerated
Carbon
r
I
|
Backwash
Wastewater
'
Backwash 1
Treated Water
Storage, and
Distribution
Backwash
Wastewater
to Disposal
20
-------
regenerated. The carbon may be regenerated either
on-site or in an off-site facility. Carbon regeneration
facilities include multihearth, fluidized bed, or
infrared furnaces. Small packaged plants may be
designed for disposal of the spent carbon in lieu of
regeneration.
Water treatment plants with sand bed filtration can
be converted to granular activated carbon treatment
by replacing the sand beds in the contactors with
carbon and making other equipment modifications
and additions.
Design Basis and Costs (2,4,5)
As discussed in the description of this technology,
various kinds of contactors and regeneration
methods are possible. Besides different kinds of
equipment, the parameters for sizing the equipment
will also determine characteristics for a given
system.
Parameters such as hydraulic loading (application
rate of water to the contactor cross-sectional area,
expressed as gpm/ft2), carbon depth, and regeneration
frequency vary according to the kind and concentration
of organics in the influent water, the final water purity
required, and the type of carbon used. The design
basis for costs presented here corresponds to the
process modules shown in Figure 2-21. The major
design criteria upon which costs are based are-listed
in Table 2-3. At system capacities of 1.0 mgd and
below, packaged plants are available although costs
for these plants are not presented here.
Capital costs, shown in Figure 2-22, are expressed as
the total capital investment for a new granulated
activated carbon treatment system as a function of
design capacity. Net annual operating expenses are
given in Figure 2-23, and unit annuitized costs are
shown in Figure 2-24. The cost curve of Figure 2-22
was plotted from estimates for three plant sizes: 2
mgd, 20 mgd, and 110 mgd design capacity. Pressure
steel contactors were assumed for the 2 mgd and 20
mgd plants, and gravity steel contactors for the 110
mgd plant. Because on-site regeneration may not be
economically justified for small plants, off-site
Table 2-3. Design Parameters for Typical Granular Activated
Carbon Systems for Drinking Water Treatment
(2,4,5)
Design flow rate, mgd
Operating flow rate, mgd
Contactor type
Empty bed contact time, min.
Hydraulic loading, gpm/ft2
Backwash pumping rate, gpm/ft2
Regeneration frequency, months
Carbon losses, %
Regeneration method
3
2
Steel
pressure
vessel
20
5
10
2
7
Off-site
20 miles
30
20
Steel
pressure
vessel
20
5
10
2
7
On-site
infra-red
150
110
Steel
gravity
vessel
20
5
10
2
7
On-site
multi- hearth
Figure 2-22. Granular activated carbon system for drinking
water treatment • Total capital investment
(March, 1980 dollars).
Costs based on regeneration frequency of 2 months.
Costs below 2 mgd are by extrapolation.
0.1 1.0 10 100
SYSTEM CAPACITY, mgd
0.5 5 50 500
I I I I
POPULATION SERVED, thousands
Figure 2-23. Granular activated carbon system for drinking
water treatment • Net annual operating expenses
(March, 1980 dollars).
Costs based on regeneration frequency of 2 months.
Costs below 2 mgd are by extrapolation.
NET ANNUAL OPERATING EXPENSES
millions of dollars per year
b P T-
o rt-- -1 ° c
i i i M 1 1 1
^
Off-Sit
., Regenera
, . , I,,,,
1 1 1 |1IT1
/
e
tion R
/.
-
On-Site
egeneration ,_
, , , l.M,
-1 1.0 10 1C
SYSTEM CAPACITY, mgd
55 50 50
POPULATION SERVED, thousands
21
-------
Figure 2-24. Granular activated carbon system for drinking
water treatment - Unit annualized cost (March,
1980 dollars).
Costs based on regeneration frequency of 2 months.
Costs below 2 mgd are by extrapolation.
1.0 10
SYSTEM CAPACITY, mgd
0.5
l_
50
100
500
POPULATION SERVED, thousands
regeneration is the basis for costs of smaller plants as
indicated. Five percent of the cost of an off-site
regional regeneration facility is apportioned to the 2
mgd plant. On-site multiple hearth furnace regenera-
tion is assumed for the 20 and 110 mgd plants. The
size ranges for the two regeneration options are
indicated on the cost curves. Actually there is not an
abrupt change at a particular size, but a range over
which the relative attractiveness of off-site versus
on-site regeneration must be compared on a case by
case basis.
Major Variables Affecting Costs
Other than plant flow capacity, the major factors
which affect overall capital costs for a granular
activated carbon treatment system are: kind and
concentration of organics in the influent water which
determines required contact time in the contactors
and hence contactor volume, carbon loading (Ib
contaminants adsorbed per Ib of carbon), and
regeneration frequency.
There is a cost trade-off between contactor volume
and regeneration frequency. If smaller contactor
volumes are used to reduce investment costs for the
carbon contactor system, more frequent regeneration
and the associated higher costs for regeneration
equipment are incurred. Likewise, regeneration
frequency and associated costs can be reduced by
using larger contactors. An investigation of the effect
of regeneration frequency on costs suggests that a
regeneration interval of about 2 to 3 months is
reasonable for granulated activated carbon systems
in drinking water treatment (9).
Net annual operating expenses are strongly influenced
by regeneration frequency, carbon losses, and fuel
costs (10).
Carbon losses occur during handling of the carbon in
charging and discharging equipment and during
regeneration. Handling losses occur due to spillage
and gradual attrition. Regeneration losses result
when some of the carbon is burned along with the
adsorbed organics during regeneration. Carbon
losses typically range from 5 to 10 percent; in this cost
summary they were assumed to be 7 percent.
2.4 Aeration
Description
Aeration is a process for removal of volatile organic
materials from drinking water. Flowing streams of air
and water are contacted with each other so that
volatile organic materials are evaporated into the air
stream and removed from the water. Aeration can be
carried out in towers or aeration basins to provide the
necessary contact between air and water. An
aeration basin is typically constructed of concrete. An
aeration tower is a rectangular structure similar to
the water cooling towers used with large air
conditioning systems. The two process options are
illustrated conceptually in Figure 2-25.
For basin aeration, the water enters one or more open
concrete contact basins. Compressed air is fed to air
diffuser pipes set in the bottom of the basins. Air
bubbles strip organic compounds from the water as
they rise to the surface. A basin is designed to allow
sufficient detention time for the air to reduce the
concentration of organic compounds in the water.
Similar to conventional cooling towers, aeration
towers might consist of a fiberglass-covered metal
framework containing a plastic packing medium. As
water introduced near the top of the tower flows
downward through the packing, it contacts airflowing
upward. An induced draft fan in the tower stack
draws in air at the bottom of the tower. Organic
materials stripped from the water leave with the exit
air stream. Treated water collects in a concrete basin
beneath the tower; from there it is pumped to storage.
Design Basis and Costs (2,4,8)
The most significant design parameter for both basins
and towers is the air-to-water ratio. Table 2-4 shows
the major tower and basin design parameters used
for the cost data presented here.
Costs for both basin and tower systems were derived
for a conceptual design based on limited laboratory
data (8). Test results for chloroform and several other
22
-------
Figure 2-25. Aeration systems for drinking water treatment.
Influent
Water
Treated
Water
influent
Water
System Boundary
Basin Aeration
Outlet
Air
Aeration
Tower &
Recirculation
Treated
Water
Tower Aeration
trihalomethanes were used to determine the sizes
required for aeration basins and towers based on
comparable performance in removing chloroform.
Since the conceptual designs and cost estimates are
based on limited laboratory data rather than pilot
plant data, the cost estimates are very preliminary.
Table 2-4.
Performance
Major Design Parameters for Aeration Basins and
Towers for Trihalomethane3 Removal in Drinking
Water Treatment (4,9)
Basins
65% Removal 90% Removal
Air-to-water ratio
Number basins in series
Air loading, scfm/ftz of
basin area
Operating temperature, °F
Basin depth, ft
Basin volume, ftVmgd
Influent chloroform
concentration, mg/l
Performance
10:1
1
5
70-80
12
2,200
10-800
20:1
2
5
70-80
12
4,400
10-800
Towers
65% Removal 90% Removal
Air-to-water ratio
Typical water loading, mgd/ftz
of tower cross-section
Design superficial air
velocity, 1 ft/sec based
on empty tower cross-section
Maximum superficial air velocity,
2.5 ft/sec based on empty
tower
Tower water pumps (one operating,
one spare) total dynamic
head, ft
Operating temperature, °F
Tower volume, ftVmgd
Tower height, ft
Influent chloroform
concentration, mg/t
10:1
0.059
1.0
2.5
30
70-80
340
22
10-800
100:1
0.059
1.0
2.5
30
70-80
3,400
22
10-800
Although organic materials other than trihalomethanes can also be
removed by aeration, the most data was available on THM removal. Also, at
the time this report was written, a major interest was in THM removal. Thus,
THM removal was the design basis for aerations.
The data showed that for 65 percent and 90 percent
removal of chloroform in aeration towers the
corresponding air-to-water ratios were 10 to 1 and
100 to 1, respectively. The data did not show a
difference between basins and towers at the 10 to 1
ratio, but it appeared that the basins might achieve
the higher removal at a ratio of 20 to 1. These design
criteria were used as the basis for the costs in this
report using cost data for basins and towers from
References 4 and 5.
As a technology for the removal of organic
compounds in general, the conditions observed in
tests with trihalomethanes might be typical of
conditions necessary for the removal of other organic
materials so that these costs apply to basins and
towers for the removal of other organic materials.
Total capital investment costs are shown in Figure 2-
26, net annual operating expenses in Figure 2-27,
and unit annualized cost in Figure 2-28. The two sets
of curves reflect the two contact options of either
basins or towers. The two curves in each set
correspond to different air-to-water ratios (and hence
removal efficiency).
Major Variable Affecting Costs
Other than type of system (basin or tower), the most
significant variable affecting costs for aeration is the
air-to-water ratio required to achieve a specified level
of performance. Air-to-water ratios that might be
required to achieve comparable levels of performance
in basins compared to towers can be expected to vary
with concentrations and kinds of organic materials in
different water supplies. The required ratio to achieve
results is also sensitive to temperature with higher
temperatures improving removal efficiency and
lowering the required air-to-water ratio. Other
23
-------
variables include details of equipment design which
could differ from those described in this report.
References - Section 2
1. Midwest Research Institute. Small System Water
Treatment Symposium, EPA-570/9-79-021.
Prepared for U.S. Environmental Protection
Agency, Office of Drinking Water, Washington,
DC, September 1979.
2. Gumerman, R.C., et al. (Culp/Wesner/Culp)
Estimating Water Treatment Costs, Vol. 1.
Summary, EPA-600/2-79-162a (PB80-139819*).
U.S. Environmental Protection Agency, Cincinnati,
OH, August 1979.
3. Clark, P.M. and R.G. Stevie. Meeting the Drinking
Water Standards in Safe Drinking Water: Current
and Future Problems. Proceedings of a National
Conference, Resources of the Future. Research
Paper 12. Washington, DC, Clifford S. Russell,
-------
Figure 2-27. Aeration for drinking water treatment • Net
annual operating expenses (March, 1980
dollars).
Basins
Approximately 65% removal of organics,
air to water ratio = 10
Approximately 90% removal of organics,
air to water ratio ±= 20
Towers
Approximately 65% removal of organics,
air to water ratio = 10
Approximately 90% removal of organics,
air to water ratio = 100
1.0 mgd by extrapolation.
).5
1.0 10
SYSTEM CAPACITY, mgd
5 50
100
fiOO
Figure 2-28. Aeration for drinking water treatment
annualized cost (March, 1980 dollars).
Basins
Approximately 65% removal of organics,
air to water ratio = 10
Approximately 90% removal of organics,
air to water ratio = 20
Unit
Towers
Approximately 65% removal of organics,
air to water ratio = 10
Approximately 90% removal of organics,
air to water ratio = 100
Curves below 1.0 mgd by extrapolation.
_i
N3
°
UNIT ANNUALIZED COST
cents per thousand gallons
_L
O
0
00
0
O)
0
4i.
0
rO
0
i \ i | 'in
\
\
\
\
\
\
r r T
TTTTTJ
0.1 1.0 10
SYSTEM CAPACITY, mgd
0.5 5 50
I I \
100
500
I
POPULATION SERVED,'thousands
POPULATION SERVED, thousands
25
-------
Section 3
Wastewater Treatment
Wastewater from domestic, municipal, and industrial
sources must be treated to remove pollutants that are
harmful to human health and the environment. Of the
more than 300 bill ion gallons of water drawn for use
in the United States each day, approximately 90
percent is used by industry (1). Although some of this
quantity is lost through evaporation or incorporated
into products, a substantial portion is discharged as
wastewater.
The four major categories of wastewater sources are:
• Steam electric power generation.
• Agriculture.
• Manufacturing and minerals production.
• Domestic, commercial, and public sources.
These sources comprise a variety of wastewater
stream characteristics requiring different types of
treatment prior to discharge. Wastewater is treated in
more than 2,500 municipal treatment plants in the
U.S. (2), as well as in numerous industrial facilities.
Historically, the body of legislation dealing with
wastewater discharges has increased gradually. But
increased national attention to this issue occurred in
the last decade. Although the federal government had
been active in funding municipal wastewater
treatment facilities since 1957 (2), the legislative
initiatives of the 1 970's provided additional impetus
for wide-scale cleanup of the nation's waterways.
The major recent legislation was the Clean Water
Acts of 1972 and 1977.
General health, aesthetic, and recreational reasons
were the early sources of motivation for water
cleanup. Prevention of long-term uncertain deleterious
effects on health and the environment is now a
growing consideration. Increasing demands on the
nation's water resources will likely increase water
reuse in many areas of the country. This wou|d
increase the use of wastewater treatment technolo-
gies.
Total capital expenditures for water pollution control
were reported as $10.9 billion in 1977. Annualized
costs were reported as $8.9 billion. Total investment
spending for water pollution control between 1977
and 1986 has been estimated at $50.7 billion in
constant 1977 dollars. Total annualized cost
expenditures have been estimated as $121.8 billion
for the same period (3).
Several categories of water pollutants are of interest.
The water pollutants controlled by the technologies
in this section are organic substances, suspended
solids, phosphorus containing compounds (both
suspended and dissolved), and ammonia.
Organic waste concentrations are commonly
expressed as 5-day biochemical oxygen demand
(BOD5), chemical oxygen demand (COD), or total
organic carbon (TOC) in milligrams per liter (mg/l).
Historically, BODg has been used to express the
biodegradable waste concentration in municipal as
well as industrial wastewater. COD provides a
measure of the presence of refractory organic
materials not amenable to biological treatment. TOC
measures total organic materials. These measures of
organic waste concentrations include both dissolved
materials and suspended solids.
Suspended solids (SS) include both organic and
inorganic, biologically inert materials such as fine
particles of silt. Organic suspended solids contribute
to a portion of the total BOD5 of the wastewater.
Phosphorus (P) is present as dissolved phosphorus
compounds as well as in some of the suspended
solids. Ammonia (NH3) is present both as dissolved
ammonia gas and in soluble compounds. Ammonia
can form from the degradation of nitrogeneous
compounds in the waste. Concentrations of all these
waste materials are usually expressed as milligrams
per liter (mg/l). Additional pollutants commonly
removed from wastewater are bacteria, viruses, and
soluble minerals which interfere with subsequent
intended uses of the treated wastewater.
Treatment technologies for removing the pollutants
discussed above with corresponding percentage
removal capabilities are listed in Table 3-1. The first
Table 3-1. Typical Pollutant Removal Efficiency of Waste-
water Treatment Technology (4,5)
Pollutant removal efficiency,
percent
Technology
BODs COD SS
NH3
Conventional secondary and
advanced wastewater treatment
Stabilization ponds and aerated
lagoons
Land treatment
Phosphorus removal by chemical
addition
Nitrification
Granular media filtration
80-95 50-70 80-90 25-45 10-20
6O-9O 70-9O 70-90 25-30 25-95
95-99 — 95-99 <90 >25
— — — 90-95 —
26
-------
three technologies listed are biological treatment
systems comprising several process steps which
remove a portion of all of the pollutants listed. The last
three systems are individual process steps which
specifically remove phosphorus, ammonia, and
suspended solids, respectively, although some
reduction in the other pollutants also occurs.
As of 1977, 737 wastewater treatment projects
funded under the Municipal Wastewater Treatment
Plants Grants Program and catalogued as part of a
cost review (6) were distributed as follows:
Activated sludge*, % 47.1
Stabilization ponds, % 11.5
Aerated lagoons, % 3.9
Other, % 37.5
Some of the systems in the "other" category included
trickling filter plants and rotating biological contactors.
The remaining kinds of systems were not identified.
For municipal wastewater treatment technologies in
this report, the typical process design and correspond-
ing costs are based on the following influent
wastewater characteristics:
BOD5, mg/l 210
Suspended solids, mg/l 230
Total phosphorus (as P}, mg/l 11
Ammonia, mg/l 19
pH 7.0
There are wide variations in industrial wastewater
characteristics. The characteristics listed above for
municipal wastewater are also typical for some cases
of industrial wastes at the low end of the BOD5
concentration range. In these cases, industrial
treatment costs will be similar to those for municipal
wastewater. However, since typical industrial BOD5
concentrations can be much greater than 210 mg/l,
the process designs in this section also consider an
influent wastewater with a BOD5 level of 1000 mg/l. It
should be recognized that this is only a special case
for industrial wastewater treatment. This particular
BOD level was selected to illustrate the effect of this
parameter on cost.
3.1 Conventional Secondary and
Advanced Wastewater Treatment
Description
Wastewater treatment processes that achieve
effluent levels of 30 mg/l or less of 5-day biochem ica I
oxygen demand, BOD5, and 30 mg/l or less of
suspended solids are referred to as conventional
secondary treatment (6). Those systems which
achieve effluent levels of 10 mg/l or less of BOD5, ang!
10 mg/l or less of suspended solids are referred to as
*The common biological treatment step in conventional secondary and
advanced wastewater treatment.
advanced wastewater treatment (6). Both types of
treatment systems can use a number of combinations
of unit processes to achieve these effluent levels.
Advanced wastewater treatment plants use the same
process operations as conventional secondary
treatment plants with additional processing steps to
achieve greater removal of pollutants. Individual
treatment plants of either kind can differ in details of
component equipment configurations and specifica-
tions because of differences in influent water
characteristics, treatment objectives, and other site-
specific considerations.
The typical conventional secondary treatment system
considered in this report contains thefollowing major
process modules:
• Preliminary treatment.
• Influent pumping.
• Primary clarification.
• Activated sludge secondary treatment.
• Secondary clarification.
• Effluent disinfection by chlorination
• Sludge treatment.
A typical advanced wastewater treatment system
contains, in addition to the above, the following
process modules:
• Primary chemical addition (prior to primary
clarification).
• Secondary chemical addition (prior to secondary
clarification).
• Granular media filtration of secondary clarifier
effluent
An additional process module, granular activated
carbon treatment, could be used after granular media
filtration, but is not considered here.
Configurations of typical systems for conventional
secondary treatment and advanced wastewater
treatment are shown conceptually in Figure 3-1 and
Figure 3-2, respectively.
Influent enters a preliminary treatment module
where debris and large suspended solids such as grit
are removed. Sometimes, the flow in preliminary
treatment is equalized in a large holding basin to
dampen the effect of fluctuations in influent flow
rates and waste loadings on downstream process
modules. Flow equalization enhances the downstream
removal of contaminants by providing a more uniform
waste stream.
Effluent from preliminary treatment flows to the
primary clarifiers. The clarifiers provide a relatively
long detention time so that a large portion of the
suspended solids can settle out. Chemical coagulants
and coagulant aids can be used to enhance the
removal of solids. Conventional systems sometimes
use chemicals; advanced treatment systems nearly
always use chemicals in this step.
Clarifiers can be either rectangular or circular, and
fabricated of either concrete or steel. Sludge (settled
27
-------
Figure 3-1. Conventional secondary treatment system for wastewater.
Raw
Waste-
water
'~l
Control Lab/
Mainte-
nance
Building
Conven-
tional
Activated
Sludge
Secondary Sludge
Second-
_ ary
Secondary | Eff|uent
System Boundary
Final
Secondary
Discharge*
< 30 mg/l
BOD5
< 30 mg/l
SS
Sludge Solids
to Disposal
by Landfill
* Effluent chlorination is not commonly used for industrial wastes.
"These effluent concentrations do not necessarily apply to industrial wastewater, but are
characteristic of effluent discharges from municipal wastewater treatment.
suspended solids) is removed from the bottom of the
clarifier vessel and is pumped to sludge treatment.
Clarifier effluent flows to the activated sludge
aeration tanks for further treatment.
Conventional activated sludge treatment is a
continuous-flow biological process. A suspension of
aerobic microorganisms is mixed into the wastewater;
the mixture of microorganisms and wastewater,
called mixed liquor, is agitated by air bubbles rising
from diffuser pipes in the bottom of the aeration
vessel or by mechanical surface aerators. The
microoganisms oxidize soluble and colloidal organic
compounds to carbon dioxide and water. The mixture
flows from the aeration vessel to secondary clarifiers
for separation of solids. These clarifiers are similarto
the primary clarifiers discussed above.
Secondary clarifiers remove some of the suspended
solids from the activated sludge aeration vessel
effluent. A portion of the solids settled out in the
secondary clarifiers is returned to the aeration tank
inlet as recycle sludge to seed biological activity in the
incoming wastewater. Excess sludge resulting from
microorganism growth is routed to the sludge
treatment processes for disposal.
In the clarifiers chemical addition can be used to
enhance settling. In conventional secondary treat-
ment, the clarified secondary effluent may be
disinfected prior to discharge. In advanced wastewater
treatment, the secondary effluent passes through
granular media filters which further reduce suspended
solids and BOD5 to the required advanced wastewater
treatment levels (BOD5<10 mg/l, SS <10 mg/l for
municipal wastewater).
For some high strength industrial wastes, some of the
secondary clarifier effluent is recycled to the
activated sludge aeration vessels in order to dilute
high levels of BOD5. Lower BOD5 levels in the
aeration vessel may be necessary to ensure the
28
-------
Figure 3-2. Advanced wastewater treatment system.
Raw
Waste-
water
Preliminary
Treatment
Control
Lab/Main-
tenance
Building
Influent
Pumping
Secondary
Chemical
Addition
Primary
Chemical
Addition
Se-
con-
dary
Efflu-
ent
Conven-
tional
Activated
Sludge
Primary
Clarifica-
tion
Secondary
Clarifi-
cation
Granular
Media
Filtration
Effluent
Chlprina-
tion*
Primary
Sludge
Secondary Sludge
System Boundary •
Sludge Sol ids
to Disposal
by Landfill
Sludge
Treatment
Final
Effluent
Discharge"
<10mg/IBOD
<10mg/ISS
* Effluent chlorination is not commonly used for industrial wastes.
**These effluent concentrations do not necessarily apply to industrial wastewater, but are
characteristic of effluent discharges from municipal wastewater treatment.
required removal efficiency. Another approach with
high strength wastes is to provide a longer detention
time in the aeration vessel than for low strength
wastes.
Sludge treatment is used to reduce the, volume of
sludge from both primary and secondary clarifiers
and to render the sludge more acceptable for final
disposal. A number of sludge treatment options may
be used. One common method is thickening,
digestion, dewatering, and final disposal by landfill.
Secondary clarifier sludge, which contains about 95
percent water, is commonly concentrated in a gravity
thickener. From this process the sludge is transferred
to a digester which chemically and physically alters
the sludge solids to facilitate ultimate disposal.
Sludge digestion can be either aerobic or anaerobic.
Anaerobic digestion, which is most commonly
employed, converts sludge into methane, carbon
dioxide, and a residual organic material. The
digestion takes place in the first of two tanks in series.
The second tank provides for settling of solids and
separation of supernatant liquid which is routed to a
previous process step. Combustible gas is collected
from both stages and used as heater fuel in the
treatment plant. Sludge is dewatered to increase the
solids content prior to final disposal.
Dewatering can be accomplished by sand-bed drying,
vacuum filtration, or centrifugation, depending on the
physical properties of the sludge. Landfill, incineration,
land spreading, and other methods are used for final
dewatered sludge solids disposal-
Conventional secondary or advanced wastewater
treatment using the activated sludge process can be
applied to both domestic wastewater and biodegrad-
29
-------
able industrial wastewater. It is not uncommon for
municipal and industrial wastewaters to be combined
for treatment. In these cases the industrial waste
cannot contain toxic materials that would render the
biological treatment process inoperative or refractory
materials that would result in effluent standards
being exceeded. Also, the industrial waste might
require special provisions for oil and grease
separation as part of preliminary treatment.
Advanced wastewater treatment achieves higher
quality effluent than can be achieved by conventional
secondary treatment. If the non-biodegradable
organic portion of the waste is large enough to cause
problems in receiving water bodies, granular
activated carbon treatment might be required to
reduce effluent organic concentrations.
Design Basis and Costs (4,6,7,8)
As shown in Table 3-2, one typical municipal and two
typical industrial wastewater compositions were
selected as the design basis for conventional
secondary and advanced wastewater treatment
systems.
Characteristics of industrial wastes vary widely,
depending on both the particular industry and the
individual operating facility. High BOD5 affects the
design of the activated sludge units, secondary
clarifiers, and sludge treatment. At high BOD5 levels,
the volume of excess sludge from microbial growth
during the activated sludge process is much greater
than any reasonable level of inert suspended solids
likely in the raw waste influent. For a given plant
capacity, activated sludge units, secondary clarifiers,
and sludge treatment systems must all be larger for
high BOD5 levels than for low BOD5 levels. This is
because the volume of sludge generated by microbial
growth increases with BOD5 level if the same food
(BODs) to microorganism ratio (F/M) is maintained.
The volume of sludge generated by microbial growth
was based on a reported value from the literature (9).
This value, the influent concentrations of Table 3-2,
and typical removal efficiencies for unit processes
were used to develop the system material balance for
sizing each unit process.
Key design parameters for the conventional secondary
treatment process are given in Table 3-3 and for the
advanced wastewater treatment process in Table 3-
Table3-2, Typical Influent Wastewater Composition
Municipal or medium High strength
strength industrial industrial
BODs. mg/l 210 1000
SS, mg/l 230 230
TotoJ phosphorus (as P), mg/l 11 —
Ammonia nitrogen, mg/l 19 —
pH 7.0 7.0
4. Some design features for the treatment systems
are outlined below:
• The preliminary treatment module contains a bar
screen and grit chamber. The grit chamber is a
horizontal flow type with mechanical grit handling.
• Influent pumping capacity is provided for twice the
overall plant design flow.
• Circular primary clarifiers have been specified.
Primary sludge pumps are included to transport
the settled solids to the sludge treatment portion of
the overall system.
• Activated sludge aeration vessels are rectangular
concrete basins sized appropriately for the
required detention time. Diffused aeration is used.
These are followed by circular secondary clarifiers
provided with sludge pumps to transfer solids to
sludge treatment. Secondary sludge is combined
with primary sludge.
• For the advanced wastewater treatment plant,
granular media filter units consist of multiple
concrete or steel vessels containing a sand bed
overlain with a bed of anthracite. Total bed depth is
from 2 to 5 ft. These units include backwash
systems.
• Effluent from the secondary clarifiers in conven-
tional treatment and granular media filters in
advanced wastewater treatment is disinfected by
chlorination prior to final discharge.
• Sludge treatment includes thickening, digestion,
and dewatering, with final disposal by landfill. The
sludge thickeners are circular tanks similar to the
clarifiers and include discharge pumps. Two-stage
anaerobic digestion is assumed. Sludge dewatering
is by vacuum filter.
• All piping and miscellaneous pumps, electrical
equipment, instrumentation, required service
auxiliaries, and buildings are included.
Two sets of cost curves for total capital investment,
plotted against plant capacity in millions of gallons
per day, are shown in Figure 3-3 corresponding to
conventional secondary treatment and advanced
wastewater treatment. Two curves in each set
correspond to different influent BOD5 levels for
municipal or medium strength industrial wastewater
and high strength industrial wastewater. In all cases,
final disposal of sludge solids is by landfill. Net annual
operating expenses that correspond to the capital
investment curves are shown in Figure 3-4. Unit
annualized cost is given in Figure 3-5.
Major Variables Affecting Costs
Among the variables that could significantly affect
the costs of conventional secondary and advanced
wastewater treatment are variations in individual
wastewater characteristics and the equipment sizing
changes that would occur as a result. The complexity
of these wastewater treatment systems makes a
quantitative analysis of such effects beyond the scope
of this discussion.
-------
Table3-3. Design Parameters for Conventional Secondary Treatment System {4,6,7}
Parameter
Primary clarifiers
Surface loading
Detention time
Activated sludge aeration
vessels
Volumetric loading
Detention time
MLVSS b
F/M ratioc
Air requirement
Secondary clarifiers
Surface loading
Gravity thickener
Solids loading
Sludge digester
Solids loading
Operating temperature
Sludge dewatering (by vacuum filter)
Sludge solids concentration
Dry solids loading
Operating schedule
1 mgd plant
10 mgd plant
1 00 mgd plant
Chemical treatment dosage
FeCh
CaO
Units
gpd/ft2
hr
IbBODs/day/IOOOft3
hr
mg/l
Ib BODs/day/lb MLVSS
ftVlb BOD5 removed
gpd/ft3
Ib/ftVday
Ib VSS/ftVd°
°F
lbsolids/106gal
Ib solids/hr/ft2
hr/day
hr/day
hr/day
lb/106gal
lb/106gal
Range
600-1,200
1.5-3.0
25-30
4-38
1,500-3,000
0.25-0.5
700-1,500
400-800
4-8
0.04-0.40
85-110
-
3.5-15
-
.
-
-
•
Design value3
800
N/A
32
6-29
2,100
0.25
700
600
6
0.16
85-110
900
5
6
12
10
35
90
N/A = Not available in cost reference used.
MLVSS = Mixed liquor volatile suspended solids in the aeration vessel, a measure of microorganism population.
F/M = Food to microorganism ratio, a measure of organic waste concentration to microorganism population.
*VSS = Volatile suspended solids, in the digester; a measure of digestible solids which can be converted to CO2 and H20.
Table 3-4. Design Parameters for Advanced Wastewater Treatment System (4,6,7)
Parameter
Units
Range
Design Value
Primary clarifiers
Surface loading
Detention time
Activated sludge aeration
vessels
Volumetric loading
Detention time
MLVSSb
F/M ratio0
Air requirement
Secondary clarifiers
Surface loading
Gravity thickener
Solids loading
Sludge digester
Solids loading
Operating temperature
Sludge dewatering (by vacuum filter)
Sludge solids concentration
Dry sofids loading
Operating schedule
1 mgd plant
10 mgd plant
100 mgd plant
Chemical treatment dosage
FeCU
CaO
(Continued)
gpd/ft'
hr
lbBOD5/day/1,OOOft3
hr
mg/l
Ib BODs/day/lb MLVSS
ftVlb BOD5 removed
gpd/ft3
Ib/ft2/day
Ib VSS/ftVd"
°F
lbsolids/10Ggal
Ib solids/hr/fta
hr/day
hr/day
hr/day
lb/106gal
lb/106gal
600-1,200
1.5-3.0
25-50
4-38
1,500-3,000
0.25-0.5
700-1,500
400-800
4-8
0.04-0.40
85-110
3.5-15
800
NAa
32
6-29
2,100
0.25
700
600
0.16
85-110
900
5
6
12
10
35
90
31
-------
Table 3-4. Continued.
Parameter
Primary and Secondary
Chemical addition
Alum dosagee
Granular media filtration1
Hydraulic loading
Run length
Backwash cycle time
Backwash hydraulic loading
Units
mg/l
gpm/ft2
hours
min.
gpm/ftz
Range
100-500
2-8
8-48
.
15-25
Design Value
TOO
4
12
15
15
aN/A = Not available in cost reference used.
MLSS = Mixed liquor volatile suspended solids in the aeration vessel, a measure of microorganism population.
^F/M = Food to microorganism ratio, a measure of organic waste concentration to microorganism population.
VSS = Volatile suspended solids; in the digester, a measure of digestible solids which can be converted to CO2 and H;>O.
"Refer to Section 3.4 of this report.
'Refer to Section 3.6 of this report.
Figure 3-3. Conventional secondary and advanced
wastewater treatment • Total capital investment
(March, 1980 dollars).
Figure 3-4. Conventional secondary and advanced
wastewater treatment • Net annual operating
expenses (March, 1980 dollars).
AWT - Industrial Waste (BOD = 1000 mg/l) —_
AWT-Municipal Industrial Waste (BOD = 210 mg/l)
CST - Industrial Waste (BOD = 1000 mg/l)
CST - Municipal Industrial Waste (BOD = 210 mg/l)
AWT - Industrial Waste (BOD = 1000 mg/l)
AWT - Municipal Industrial Waste (BOD = 210 mg/l)
CST-Industrial Waste (BOD = 1000 mg/l)
CST - Municipal Industrial Waste (BOD = 210 mg/l)
Costs based on sludge dewatering by vacuum filtration. Costs based on sludge dewatering by vacuum filtration.
For conventional secondary plants of 1 mgd and below,
sludge dewatering by drying beds would reduce costs
by about 33%.
For conventional secondary plants of 10 mgd and above,
incineration of sludge would increase costs approximately
16% for waste at 210 mg/l BOD and 7% for waste at
1000 mg/l BOD.
1000
0.7
or -ro
SYSTEM CAPACITY, mgd
7 70
1 I
POPULATION SERVED, thousands
32
TOO
700
_J
For conventional secondary plants of 1 mgd and below,
sludge dewatering by drying beds would reduce costs
by about 23%.
For conventional secondary plants of 10 mgd and above,
incineration of sludge would increase costs approximately
25% for waste at 210 mg/l BOD and 18% for waste at
1000 mg/l BOD.
CO
LJJ
CO
QJ
I!
Oo
Is
UJ
100 r 1—i | | 11 M
100
700
0.1
0.7
1.0 10
SYSTEM CAPACITY, mgd
7 70
POPULATION SERVED, thousands
-------
Figure 3-5. Conventional secondary and advanced
wastewater treatment - Unit annualized cost
(March, 1980 dollars).
AWT - Industrial Waste (BOD = 1000 mg/l) _
AWT- Municipal Industrial Waste (BOD = 210 mg/l) - ——.
CST-Industrial Waste (BOD = 1000 mg/l)
GST - Municipal Industrial Waste (BOD = 210 mg/l)
Costs based on sludge dewatering by vacuum filtration.
For conventional secondary plants of 1 mgd and below,
sludge dewatering by drying beds would reduce costs by
about 30%.
For conventional secondary plants of 10 mgd or above,
incineration of sludge would increase costs approximately
20% for waste at 210 mg/l BOD and 11% for waste at
1000 mg/l BOD.
DUALIZED COST
housand gallons
--. 5
0 C
0 C
0 C
i5
< 0.
1- « 100
Z c
= s
10
0
I I ! [M I!
^
r<%
1 1 1 1 1 1 1 1
I I 1 |MM
?^^
**.. ^ •
*»fc
1 1 1 jllir
*****r,
1 1.0 10 10
SYSTEM CAPACITY, mgd
0
7 7 70 7C
POPULATION SERVED, thousands
Any of a large number of significant factors can
impact costs, depending on the value of each variable.
Some of these variables are:
Influent waste loadings.
Solid settling characteristics.
Specific chemical composition of the waste.
Operating temperatures.
Aeration methods.
Sludge properties.
Sludge treatment methods.
Plant labor, energy and maintenance requirements.
In addition individual architectural features and plant
layout can be a significant factor for these plants
because of the large number of process steps.
Individual plant administrative and operating
practices can significantly affect operating expenses.
3.2 Stabilization Ponds and Aerated
Lagoons
Description (4,6,7,10)
Ponds, or lagoons, are earthwork structures which
can be below grade, at grade with earthworkdikes, or
built by damming a natural terrain depression. The
ponds can be unlined or lined with relatively
impermeable clay, rubber, or plastic. They can be
subdivided by earthwork partitions into several
compartments or cells which provides for flexibility of
operation. Thisflexibility makes it possible to optimize
effluent quality. For example, each compartment can
operate separately, or there can be circulation
between compartments. Compartments may operate
in parallel or in series.
Ponds treat wastewater by providing detention time
for biological oxidation of BOD5 and settling of
suspended solids. The settled solids undergo
anaerobic decomposition at the bottom of the pond.
Detention time depends on individual wastewater
characteristics, pond waste loading (Ib BODs/acre/
day), and operating temperature.
Ponds can be divided into two general classifications:
an impounding, or absorption pond or a flowthrough
pond (10). An impounding or absorption pond relies
on percolation and evaporation to accommodate
continued wastewater additions to the pond. Intermit-
tent discharge can occur when peak flows exceed the
pond's surge capacity.
Flowthrough ponds are of four basic types:
• Aerobic algae ponds.
• Facultative ponds (aerobic upper layer and
anaerobic lower layer).
• Anaerobic ponds.
• Aerated ponds (aerated lagoons).
The first three types can be referred to as stabilization
ponds; although, in this report, the term is reserved
for facultative ponds. The above ponds differ in
functional characteristics which are discussed
below.
Aerobic ponds rely on algae growth to provide the
oxygen necessary to satisfy the wastewater BOD5
requirement. The depth of these ponds is, consequently,
restricted to less than 5 ft to permit sunlight
penetration. Some mixing is required to ensure good
oxygen distribution. These shallow ponds rely on
natural circulation. Provisions must also be made for
separating the algae from the treated water prior to
discharge. Sometimes this is accomplished by
overflow design and sometimes a separate earthwork
compartment or clarifier is provided for solids'
settling prior to effluent discharge.
A facultative pond (stabilization-pond) contains an
upper water layer which behaves in the same manner
as an aerobic pond. The bottom water layer and
sludge on the pond bottom provide an anaerobic
-------
environment where organic materials decompose to
produce methane and other gases. Depths for these
ponds range from about 3 to 6 ft.
Anaerobic ponds are anaerobic throughout their
volume. They are relatively deep to minimize odor
generating surface area and to retain heat so that
anaerobiosis can proceed.
Aerated lagoons rely on mechanically promoted
oxygen transfer to the wastewater. Diffused aeration
or mechanical aeration systems can be used. These
lagoons range in depth from 6 to 20 ft and can be
subdivided into cells by earthwork partitions.
Although upper layers of the pond are well aerated,
anaerobic decomposition of solids does occur on the
pond bottom. Surface mechanical aeration can be fix-
mounted or floating, according to agitator design. The
diffused air systems consist of perforated plastic
pipes supported near the bottom of the cells.
Regularly spaced sparger holes are drilled in the tops
of the pipes.
A large fraction of the incoming solids and of the
biological solids produced from waste conversion
settle to the bottom of the lagoon cells. As the solids
begin to accumulate, a portion will undergo anaerobic
decomposition. Suspended solids removal is enhanced
if the design includes several smaller aerated
polishing cells following the last aerated cell. In some
lagoon designs, when high-intensity aeration
produces completely mixed (all aerobic) conditions, a
final settling tank with solids recycle is required.
Periodically solids must be removed from ponds and
hauled to a landfill. Ponds are usually designed for
years of service before cleanout is required.
Ponds can be used for both municipal and industrial
wastewater where biological treatment is effective.
Removal of BOD5 ranges from about 60 percent to
over 90 percent depending on wastewater character-
istics and system design parameters. Ponds are
commonly used where land is inexpensive and
treatment costs and operational requirements are to
be minimized.
A conceptual representation of pond technology is
shown in Figure 3-6.
Rgure 3-6. Stabilization pond or aerated lagoon system
for wastewater treatment.
Influent
Wastewater"
Pond
System Boundary
Treated
Effluent
Only for aerated lagoon.
Design Basis and Costs (2,4,11)
A typical pond system requires excavation and
embankment construction, the seeding of earthwork
slopes, embankment protection, hydraulic control
works, aeration equipment (for aerated lagoons), and
electrical equipment. Design of lagoons and ponds
can be based on either detention time or BOD5
loading per unit pond area. Within the range of
detention times provided, an influent BOD5 concen-
tration of 210 mg/l results in the BOD5 pond area
loadings shown in Table 3-5. Costs are based on
adjustments of published data for a BOD5 loading of
1200 Ib BODs/acre/day to determine the costs for
different detention times. Stabilization ponds
typically have longer detention times than do aerated
lagoons because of lower rates of oxygen transfer and
corresponding rates of waste treatment. Typical
design parameters for pond systems are presented in
Table 3-5 (4,7,10).
Table 3-5. Design Parameters for Pond Systems (4,7,10)
Aerated lagoons
aDesign basis for all cases includes oxygen requirement of 0.7 - 1.4 Ib/lb BOD5 removed.
Stabilization ponds
Parameter11
Influent BOD5 loading, mg/l
Detention time, days
Depth, ft
Organic loading,
Ib BODs/acre/day
Power requirement.
hp/106gal capacity
Range
—
3-10
6-20
10-1200
30-40
Design value
210
7
15
1200
36
Range
—
3-30
0.6-10
20-500
—
Design value
210
15
3
40
34
-------
Total capital investment is presented in Figure 3-7.
Net annual operating expenses are presented in
Figure 3-8 and unit annualized cost in Figure 3-9. The
large variability that can occur in construction
features and the corresponding effects on costs are
so great for this technology that costs for site-specific
cases should be expected to vary considerably from
these cost curves.
Figure 3-7. Stabilization ponds and aerated lagoons for
wastewater treatment - Total capital investment
(March, 1980 dollars).
Stabilization Pond, Industrial Waste,
BOD = 1000 mg/l
Stablization Pond, Municipal Waste,
BOD = 210mg/l
Pond BOD Loading = 40 Ib BOD/acre/day
Aerated Lagoon, Industrial Waste,
BOD s 1000 mg/l
Aerated Lagoon, Municipal Waste,
BOD = 210 mg/l
Lagoon BOD Loading = 1200 Ib BOD/acre/day
100
LU JS
a o
< =
0.1
0.7
L_
1.0 10
SYSTEM CAPACITY, mgd
70
100
700
POPULATION SERVED, thousands
Major Variables Affecting Costs
As explained above, because a pond is primarily an
earthwork construction, costs can be very site
specific. Parker (11) listed the following major factors
in determining investment cost:
• Land availability and price.
• Pond surface area.
• Depth.
• Pond configuration.
• Terrain features.
• Dam or dike description.
Figure 3-8. Stabilization ponds and aerated lagoons for
wastewater treatment • Net annual operating
expenses (March, 1980 dollars).
Stabilization Pond, Industrial Waste,
BOD = 1000 mg/l
Stabilization Pond, Municipal Waste,
BOD = 210 mg/l
Pond BOD Loading = 40 Ib BOD/acre/day
Aerated Lagoon, Industrial Waste,
BOD = 1000 mg/l •
Aerated Lagoon, Municipal Waste,
BOD = 210 mg/l
Lagoon BOD Loading = 1200 Ib BOD/acre/day
Net annual operating expenses excluding generai expenses
would be about 27% less for aerated lagoons and
70% less for stabilization ponds.
LU
0.1
0.7
1.0 10
SYSTEM CAPACITY, mgd
7 70
100
700
POPULATION SERVED, thousands
• Volume of earthwork involved.
• Type of earthwork.
• Pond lining requirements.
• Auxiliary construction.
The first cost item, the cost of the land itself, is highly
sitespecific. Pond surface area is determined either
from a specified pond depth and the average
detention time of the wastewater impounded or from
a permissible organic waste loading in the pond.
These depend on individual wastewater characteristics.
Depth significantly influences cost because of dike
construction requirements. Dikes are wider at the
bottom than at the top. As pond depth increases for a
given surface area, the volume of earthwork in the
dike increases by a greater amount than the increase
in pond volume. Therefore, dike construction costs
increase more rapidly as pond depth increases.
55
-------
Figure 3-9. Stabilization ponds and aerated lagoons for
wastewater treatment - Unit annualized cost
{March, 1980 dollars).
Stabilization Pond, Industrial Waste,
BOD = 1000 mg/l
Stabilization Pond, Municipal Waste,
BOD = 210mg/l
Pond BOD Loading = 40 Ib BOD/acre/day
Aerated Lagoon, Industrial Waste,
BOD = 1000 mg/l
Aerated Lagoon, Municipal Waste,
BOD = 210 mg/l
Lagoon BOD Loading = 1200 Ib BOD/acre/day
Unit annualized cost based on net annual operating
expenses without general expenses would be about 15%
less for aerated lagoons and 46% less for stabilization
ponds.
0.1
0.7
1.0 10
SYSTEM CAPACITY, mgd
7 70
I I —
100
700
j
POPULATION SERVED, thousands
Pond configuration refers to shape and whether or
not the pond is subdivided by earthwork partitions.
Again there is a significant impact on the cost of dike
construction. For a given surface area, dike perimeter
increases in going from a square pond to a
rectangular one. Because dike cross-sectional area is
fixed, the total earthwork required increases.
Site-specific construction costs are greatly influenced
by existing terrain features. Valleys, pits, hillsides,
quarries, and other aspects of a particular site
influence construction of dikes and dams. Ease of
excavation is also a factor. Where excavation is
relatively easy, the pond can be partly dug below
grade and the material removed can be used for dike
construction. Where the subsoil is rock or hardpan,
material for dike construction may have to be
acquired elsewhere, or blasting may be required.
Earthmoving costs can range from low values of less
than $1/cu yd to over $10/cu yd where blasting is
required (11, 1 2, 13}. Since most of the construction
cost for an unlinedpond involves earthwork, costs for
ponds can vary widely.
A final major component of ponds which significantly
affects costs is the pond finer. Concrete liners can be
used for small ponds of less than 1 acre. Clay linings
or plastic linings can be used for larger ponds. Capital
investment for a plastic lined pond may cost
approximately 75 percent more than an unlined pond.
3.3 Land Treatment
Description
Land treatment is the application of wastewater
direcJy to land areas. The wastewater is distributed
over the land surface in basins or furrows by
sprinkling or by overland flow. Waste materials are
removed by filtration, adsorption, ion exchange,
biological action, and plant uptake as the wastewater
infiltrates the soil and/or passes over the surface.
The wastewater is usually pretreated by either
primary treatment or by a combination of primary and
secondary treatment. The pretreatment requirements
depend on the raw wastewater composition and
location of the land treatment area relative to the
waste source and on the use classification of the
agricultural crops that might "be grown on the
treatment land (4). After pretreatment, wastewater is
piped to on-site storage tanks or basins and periodi-
cally discharged to the land treatment distribution
system.
When the wastewater is permitted to percolate
extensively through the soil, the treatment is referred
to as infiltration. Infiltration treatment can be either
slow-rate or rapid-rate. In slow-rate treatment, the
wastewater is usually applied by sprinklers to
moderately permeable soils. Site specific factors
determine whether the sprinkler system is hand
moved, mechanically moved, or permanently set (4).
Rapid rate treatment is applied to deep and highly
permeable soils such as sands or sandy loam. The
water feeds from shallow basins formed by dikes
constructed from surface soil. The underlying sandy
soil within the basin then acts as a filtration medium.
The wastewater distribution system continually
supplies water to maintain a constant level in the
basin during the application period, which may range
from several hours to weeks.
Infiltration treatment systems can be designed to
include underdrainage. Underdrainage consists of a
network of drainage pipe buried beneath the land
surface to recover the effluent, control groundwater
contamination, or minimize the horizontal subsurface
flow of leachate to adjoining property. The underdrain-
age network is usually intercepted by a collection
36
-------
ditch. Water can be recovered from the collection
ditch for reuse or discharge to a receiving water body.
When wastewater does not percolate extensively, the
procedure is referred to as overland flow. In this case,
the wastewater is applied to the land at the upper end
of a slope and allowed to run across the vegetated
land surface into runoff ditches. Water quality is
improved by physical, chemical, and biological
interaction with a relatively impermeable surface soil
layer.
A conceptual representation of land treatment
systems is shown in Figure 3-10.
Land treatment can be used for municipal and certain
industrial wastewaters. Preferably, these wastewaters
should contain plant nutrients and be free from toxic
materials. Municipal wastewater treatment by these
methods produces effluents with BOD5 and suspended
solids concentrations both well below the 30 mg/l
criterion of conventional secondary treatment.
Design Basis and Costs (4,6)
The potential for design variations in land treatment
systems is so great that only general considerations
are discussed here. These are consistent with the
costs presented in one reference (4). The design basis
for costs in another publication was not available{6).
A summary of the design parameters is provided in
Table 3-6. Costs are presented only for infiltration
systems. Costs for other systems fall between the
extremes of slow rate infiltration with and without
underdrainage.
Sprinkler systems are used for slow rate infiltration.
Costs include the use of bulldozer-type equipment for
site clearing of brush and a few trees. Spray system
specifications are as indicated in Table 3-6. A solid set
or center pivot spray system is included. The design
includes a 75-day wastewater storage reservoir with
a distribution pumping station, standby pumps built
into the dike of the reservoir, continuously cleaned
water screens, all controls, and electrical work.
Underdrainage is included for the category of slow-
rate infiltrat ion. The system does not include costs for
pretreatment, monitoring wells, or transmission of
water to and from the treatment facility.
Table3-6. Design Parameters for Land Treatment (4)
Slow Rate Infiltration
Parameter
Field area required
Application rate
BOD5 loading
Soil depth
Soil permeability
Underdrain depth
Spacing
Application method
Units
acres/mgd
ft/yr
Ib/acre/d
ft
in./h
ft
ft
-
Range
56-560
2-20
0.2-5
2-5
0.06-2.0
4-10
50-500
Sprinkling
Design Value3
N/Ab
10
N/A
N/A
N/A
With and
without
N/A
Sprinkling
N/A - Not available in cost Reference 4. Application rate was the
only basts given for published cost data.
"The field area used for estimating the cost of land was 157
acres/mgd.
Total capital investment costs are plotted against
design flow rate in millions of gallons per day in
Figure 3-11. Several cost curves reflect the major
variations in land treatment systems discussed
above. The highest curve is for a slow-rate, sprinkler-
fed, underdrained system. The lowest curve is for a
slow-rate, gravity-fed system without underdrains.
Costs for rapid and overland systems fall between
Figure 3-10. Land treatment system for wastewater
r
Influent from
Transmission
System
Treated Effluent
to Reuse or
Receiving
Water Body
System Boundary
37
-------
Figure 3-11. Land treatment for wastewater treatment •
Total capital investment (March, 1980 dollars).
Slow Rate, Sprinkler-Fed, with underdrains
Slow Rate, Gravity-Fed, without underdrains - — — — -
05 m
UJ _™
Q- O
< =
SE
<
O
10
1.0
0.1
0
0
1 1 1 1 1 1 1 [
\ /
/ \
r X
X
Xi.,,.
i . r |iiii
X
X
X
, . , 1,,,,
F . i (MI,.
-
=
, , , 1,.,,
1 1.0 10 10
SYSTEM CAPACITY, mgd
7 7
7
3 70
POPULATION SERVED, thousands
Figure 3-12. Land treatment for wastewater treatment -
Net annual operating expense (March, 1980
dollars).
Slow Rate, Sprinkler-Fed, with underdrains ^^^^^—
Slow Rate, Gravity-Fed, without underdrains - — — — —
1.0 10 100
SYSTEM CAPACITY, mgd
0.7
70
700
I
POPULATION SERVED, thousands
these two curves. Design details for the actual
systems were not published, but costs reported for
actual installations fell between these curves (6).
Operating costs expressed as net annual operating
expenses are given in Figure 3-12. Unit annualized
costs are given in Figure 3-13.
Major Variables Affecting Costs
It is highly speculative to generalize land treatment
costs because local conditions have such a significant
impact. The influence of some specific major
variables can be discussed, however, to illustrate
their relative significance for most systems.
The major factors in costs for land treatment are (11):
• Land Costs.
• Wastewater transmission costs to site.
• Site development costs including:
- Relocation costs.
- Land preparation.
- Surface runoff control.
- Subsurface drainage.
- Distribution and irrigation.
- Storage lagoons.
- Pretreatment.
Land costs are highly variable, but would probably be
relatively low in any area where land treatment would
be considered as a viable treatment option.
Figure 3-13. Land treatment for wastewater treatment •
Unit annualized cost (March, 1980 dollars).
Slow Rate, Sprinkler-Fed, with underdrains
Slow Rate, Gravity-Fed, without underdrains
300
0.1
0.7
1.0 10
SYSTEM CAPACITY, mgd
70
I
POPULATION SERVED, thousands
100
700
_J
38
-------
Costs of transmitting the wastewater to the site are
highly variable and depend on the distance between
the land treatment areas and the wastewater source.
The transmission system is beyond the scope of the
design considered in this report.
Site development costs are known to have varied by a
factor of 36 for different locations (12). These costs
include the various subcomponents listed above.
Gulp, et al. (12) present a table summarizing the effect
of various conditions on spray irrigation land
treatment costs per acre. These conditions are
classified as very favorable, moderately favorable,
and unfavorable. Exclusive of system component,
transmission, storage, or pretreatment costs, the
ratio of costs with unfavorable to favorable treatment
conditions was about 5 to 1.
As with capital investment costs, operating costs can
vary widely. Labor, material, and energy requirements
reflect site-specific factors. Further discussion of land
treatment costs is given by Reed, et al.(13).
3.4 Phosphorus Removal by Chemical
Addition
Description
Phosphorus is found in certain wastewaters as
soluble chemical compounds and can be present in
some suspended solids. Chemical addition is used to
remove phosphorus in both the dissolved and
suspended forms. Chemicals react with the dissolved
phosphorus compounds (usually phosphates) to
precipitate solids which can be removed by
subsequent sedimentation in standard clarifiers.
Three primary chemicals employed are lime, alum,
and ferric chloride. The chemicals also help to
coagulate suspended phosphorus solids (either
precipitated from solution by chemical addition or
originally present in the influent), thus facilitating
their removal via sedimentation. Phosphorus removal
efficiencies as high as 95 percent can be achieved
using the chemical addition process (5).
The treatment chemicals can be added separately or
in combination at various points in the overall
treatment process. Possible points of addition include
the primary clarifiers, activated sludge vessels, or
secondary clarifiers in a conventional secondary or
advanced .wastewater treatment plant. These
chemical additions are sometimes accompanied by
the addition of polymers to further improve
coagulation and sedimentation of solids.
Alum and ferric chloride may be purchased in dry
form and prepared as solutions on-site or they may be
purchased directly as solutions. The solution is
metered from a holding tank to the point of application
in either case. Lime is obtained dry and slaked with
water to form a solid-liquid slurry. The slurry is
similarly metered to the point of application. Figure 3-
14 illustrates the major features of typical chemical
addition systems.
Figure 3-14. Phosphorus removal by chemical addition (or wastewater treatment.
Dry
Chemical
Storage &
Handling I
I
Solids
to
Landfill
Influent
Containing
Phosphorus
r——•—•-
Application point:
Primary Clarifiers,
Aeration Basins,
or Secondary
Clarifiers
Effluent with
Up to 95%
of Influent
Phosphorus
Removed
39
-------
Chemical addition can be used to remove phosphorus
in municipal wastewatersand in industrial wastewa-
ters where there are no substances in the wastewater
that would interfere with the physical-chemical phos-
phorus removal mechanism. Dosage depends on the
characteristics of the wastewater being treated.
Chemical treatment for phosphorus removal can be
an add-on to existing or new secondary treatment
plants, or it can be incorporated into independent
physical-chemical treatment and tertiary treatment
schemes, such as an adjunct to granular media
filtration.
Design Basis and Costs (4,6,14,15)
For an alum or ferric chloride liquid feed system, the
storage tank is designed for a 15-day supply of alum
solution (49 percent strength) or ferric chloride
solution (40 percent strength). The metering pump
and piping are sized for twice the operating capacity.
A building is included to house all major equipment
for systems greater than 1 mgd. Smaller systems are
not housed.
When the chemicals are received and stored in dry
bulk form, the system would include additional
equipment for dry chemical storage and handling,
an agitated mix tank for liquid solution or slurry
makeup, and the components of the liquid feed
system described above.
Dosages for a phosphorus removal system are
determined by jar test on the waste being treated. To
reduce an influent phosphorus level of about 10 mg/l
to less than 3.0 mg/l, typical chemical dosages are {4,
14, 15):
Alum, mg/l 200
Ferric chloride, mg/l 100
Lime, mg/l 150
Total capital investment is presented in Figure 3-15
as a function of the wastewater treatment plant
design capacity. Cost curves are shown for an alum
wet chemical feed system at two dosage levels
(expressed as mg/l of alum). These costs correspond
to the design basis discussed above and are
presented schematically in Figure 3-14.
Net annual operating expenses are given in Figure 3-
16 and unit annualized cost in Figure 3-17 as a
function of the wastewater treatment plant design
capacity. Again, multiple curves correspond to two
dosage levels.
The upper curves correspond to dosages that would
probably be required for phosphorus concentrations
between 13 mg/l and 17 mg/l. The lower curves
correspond to dosages for phosphorus concentrations
in a range of about 5 to 9 mg/l. Costs for typical
municipal wastewater phosphorus removal fall in the
mid-range of the costs shown in the figures.
Figure 3-15. Phosphorus removal for wastewater treatment
- Total capital investment (March, 1980 dollars).
High Alum Dosage, 300 mg/l
Low Alum Dosage, 100 mg/l _____
Includes chemical feed system and incremental cost of
clarifiers, sludge treatment, and sludge handling to
accommodate increased sludge volume over plant not
using phosphorus removal.
100 r
1.0 10
SYSTEM CAPACITY, mgd
0.7
I
70
i
100
700
I
POPULATION SERVED, thousands
Major Variables Affecting Cost
The cost curves show the significant impact of dosage
level on system cost. Dosage depends on influent
phosphorus levels and pH which will vary for
individual wastewater streams.
3.5 Nitrification (Separate-Stage)
Description
Nitrification is a biological process for ammonia
removal in which ammonia is oxidized to nitrates and
nitrites. Two uses of nitrification are:
• To convert nitrogen in ammonia to a form that can
be removed in a downstream denitrification
process.
• To convert nitrogen in ammonia to a form that does
not have to be removed from the wastewater.
The cost information presented here is for separate-
stage nitrification, which achieves the latter goal.
Single-stage nitrification occurs when operating
conditions in the activated sludge process are
adjusted to permit nitrogenous as well as carbona-
ceous oxidation to take place in the same aeration
vessels. Separate-stage nitrification is a modified
40
-------
Figure 3-16. Phosphorus removal for wastewater treatment
- Net annual operating expenses (March, 1980
dollars).
High Alum Dosage, 300 mg/l ^^—^—
Low Alum Dosage, 100 mg/l — — — —
Includes chemical feed system and incremental cost of
clarifiers, sludge treatment, and sludge handling to
accommodate increased sludge volume over plant not
using phosphorus removal.
10
1.0 10
SYSTEM CAPACITY, mgd
0.7
70
100
700
Figure 3-17. Phosphorus removal for wastewater treatment
• Unit annualized cost (March, 1980 dollars).
High Alum Dosage, 300 mg/l •
Low Alum Dosage, 100 mg/l — —-
Includes chemical feed system and incremental cost of
clarifiers, sludge treatment, and sludge handling to
accommodate increased sludge volume over plant not
using phosphorus removal.
CO O
°a
8?
N co
_J CO
Zl-
m
< Q.
Z c
uuu
1.0C
i ii nil
\
E\
_ N
.1 1
• ! II MM
~~~ .
.0 1
I I 1 | M 1 I.
j i i 1 i i i i
0 1C
SYSTEM CAPACITY, mgd
0.7
70
700
l
POPULATION SERVED, thousands
POPULATION SERVED, thousands
single-stage process in which carbonaceous oxidation
and nitrogenous oxidation occur in two separate
aeration vessels and clarifier systems. The carbona-
ceous oxidation is the standard activated sludge
process.
The nitrification system depicted in Figure 3-18 is
designed to follow a high-rate activated sludge
system. Since the process is pH sensitive, pH
adjustment may be required as indicated. The
incoming wastewater contains ammonia which is
oxidized in two steps by autotrophic aerobic
organisms called nitrifiers. Some organisms convert
the ammonia to nitrite; others convert the nitrite to
nitrate.
Design Basis and Costs (4,6,16)
Major design parameters and design values are given
in Table 3-7. Secondary effluent is pumped to a plug
flow (as opposed to completely mixed) nitrification
tank constructed of concrete. The system also
includes clarifiers (settling tanks) and all associated
piping, pumps, electrical equipment, and instrumen-
tation. Equipment for pH adjustment is not included
but might be required for specific wastewater
streams.
Total capital investment costs for a nitrification
system with the design parameters shown in Table 3-
7 are presented in Figure 3-19.
Net annual operating expenses are given in Figure 3-
20, and unit annualized cost in Figure 3-21.
Major Variables Affecting Costs
As with other treatment systems with multiple
components, equipment configuration can significant-
ly affect costs. For example, one or several clarifiers
could be used for the clarification step, and such a
choice would probably alter capital investment costs
by about 25 percent. A key design parameter that
impacts tank volume, and therefore cost, is the mixed
liquor volatile suspended solids (MLVSS) concentra-
tion required for the specific wastewater being
treated. This requirement is roughly proportional to
influent ammonia concentration. Over the typical
operating range for this process, the reactor volume
required for a high MLVSS concentration can be
twice that for a low concentration. The capital cost of
a high MLVSS concentration is about 50 percent
more than that of a low concentration.
Operating expenses are also affected by the variables
discussed above.
41
-------
Figure 3-18. Separate-stage nitrification system for wastewater treatment.
Secondary
Treatment
(NH3)
pH Adjustment
(if req'd)
j
~
Nitrified
Plug-Flow | Wastewater
" ^ Nitration Tank • 5^63171
(Reactor) I (NOs, NOa) *
Sludge Recycle
Clarif
<^^H
i
|
>
System Boundary!
Effluent
Denitrification
Waste
Sludge
Table 3-7. Design Parameters for Nitrification (Separate-Stage) (4)
Equipment Parameters
Range of values
Design basis
Nitrification
tanks (reaction)
Aeration
equipment
Clarifiers
Sludge pumps
Type
Waste loading (depends on temperature
as well as MLVSS"), Ib NH3-Nitrogen
lb/day/1000ft3
Operating temperature, °C
MLVSS*, mg/l
Detention time, hr
Mean cell residence time, days
Oxygen requirement, Ib/lb NH3-Nitrogen
oxidized
Dissolved oxygen (minimum), mg/l
pH
Type
Overflow rate, god/ft2
Solids loading, Ib/d/ft*
Depth, ft
Sludge recycle
Plug-flow or complete mix
2.5-35
5-25
1000-2000
0.5 - 3.0
10-20
N/A
2.0
7.2 - 8.5
Mechanical or diffuser
oxygen or air
400-1000
20-30
12-15
50%-100% operating average flow
Plug-flow
N/Ab
20
N/A
3
N/A
4.5
N/A
8.4
Diffuser with air
600
N/A
12
Sized for twice
operating flow rate
50%
"Mixed liquor volatile suspended solids.
"N/A - data not available.
42
-------
Figure 3-19. Nitrification (separate-stage) for wastewater
treatment • Total capital investment (March,
1980 dollars).
100 c
LLJ
fee 10
111 ™
Z
Q. O
< =
O 1.0
0.1
0.1
0.7
1.0 10
SYSTEM CAPACITY, mgd
7 70
I I
100
700
I
Figure 3-21. Nitrification (separate-stage) for wastewater
treatment - Unit annualized cost (March, 1980
dollars).
240
0.1
0.7
1.0 10
SYSTEM CAPACITY, mgd
7 70
I I
100
700
I
POPULATION SERVED, thousands
POPULATION SERVED, thousands
Figure 3-20. Nitrification (separate-stage) for wastewater
treatment • Net annual operating expenses
(March, 1980 dollars).
w
111
UJ ^
§1
XNNUALOPER)
millions of dol
p
LU
z
m
_ , , , |MM
—
L
:
\^^
.
, , , IMM
, , 1 |MM
/
, , , EMM
1 1 1 [Mil.
—
/
/ 1
-
-I
-
, , , I..M
'0.1 1.0 10 100
SYSTEM CAPACITY, mgd
0.7 7 70 700
I j | I
POPULATION SERVED, thousands
3.6 Granular Media Filtration
Description
Granular media filtration is a treatment process used
for the removal of suspended solids such as biological
floes or chemical floes from secondary effluent. It can
serve as a final polishing step or as a pretreatmentfor
other processes where suspended solids interfere
with performance such as granular activated carbon
or reverse osmosis.
A granular media filter consists of either steel or
concrete vessels containing the filter media. Steel
vessels can be fed by either pressure flow or gravity
flow. Concrete vessels are fed by gravity flow. Vessels
may be subdivided into several compartments. The
vessels contain specially designed support structures
in the bottom to permit optimum drainage of the
media.
Graded sand and anthracite coal are usually used asa
filter media in dual media filters. In downflow filters,
the sand is put in first and the coarser anthracite
medium placed on top of the sand.
As wastewater flows through thefilter bed, solidsare
deposited within the spaces between particles of the
granular media. As solids build up, the pressure drop
across the filter increases. At a predetermined
pressure drop, the process flow is diverted to a
parallel filter compartment or separate filter vessel
while the first unit is cleaned by backwashing.
43
-------
In the backwash cycle, some previously filtered water
is pumped through the filter in the reverse flow
direction to remove the deposited solids from the bed.
Compressed air is sometimes introduced with the
water to create a turbulent scouring action that
dislodges compacted solid deposits.
Backwash water, containing the original wastewater
solids at a much higher concentration than the
original wastewater, is routed back to either existing
clarifiers or vacuum filters for solids removal. The
solids are disposed of with other treatment plant
sludge.
Design Basis and Costs (4,6,15,17,18,19)
A complete filter system contains the major process
elements shown in Figure 3-22. The filter unit
generally consists of a vessel; the filter media;
structures within the vessel to support the media;
influent pumping and distribution devices; effluent
pumps; and a backwash system of pumps, piping, and
storage tanks. In addition to equipment, a building to
house the filter system is included.
Design parameters and values upon which cost data
is based are given in Table 3-8.
Total capital investment as a function of filter system
capacity in millions of gallons per day is given in
Figure 3-23. Figure 3-24 presents net annual
operating expenses and Figure 3-25, unit annualized
cost plotted against filter system capacity in millions
of gallons per day.
Table 3-8. Design Parameters for Granular Media Filtration
(4,16,18,19,20)
Design Value Typical Range
Hydraulic loading, gal./min/ft2
Run length, hr
Backwash cycle time, min
Backwash hydraulic loading,
gal./min/ft2
Pump specifications:
Type:
TDH, ft (overall)
Efficiency, %
Backwash holding tank:
Bed depth, ft
Media depth ratio
(sand to anthracite):
Air scour rate, scfm/ft2
Terminal head loss, ft
4
12
15
15
Centrifugal
14
65
Capacity for two
backwash cycles
—
—
—
—
2-8
8-48
—
15-25
—
2 to 4
1:1 to 4:1
3 to 5
6 to 15
Major Variables Affecting Costs
Capital investment for granular media filtration
systems is sensitive to the hydraulic loading rate
(gpm/ft2) which in turn is determined by influent
solids concentrations. Different design rates change
filter vessel cross-sectional area and hence cost.
Within the normal operating range, cost differences
due to changes in loading are about 25 percent for the
total system. The choice between steel or concrete
vessels also affects costs. Concrete becomes more
economical for very large systems.
Operating expenses are most sensitive to pump
power requirements and frequency of backwashlng.
Figure 3-22. Granular media filter system for wastewater treatment.
Spent
Backwash
Water to
Sewer
Influent
Wastewater
Intermittent
Backwash
Water
Effluent
i System Boundary
44
-------
Figure 3-23. Granular media filtration for wastewater
treatment • Total capital investment (March,
1980 dollars).
100
UJ
is
in "J5
> o
Z T>
a. o
10
c 1.0
0.1
J I I III1
n—r
0.1
0.7
1.0 10 100
SYSTEM CAPACITY, mgd
7 70 700
POPULATION SERVED, thousands
Figure 3-25. Granular media filtration for wastewater
treatment • Unit annualized cost (March, 1980
dollars).
120
0.1
0.7
1.0 10
SYSTEM CAPACITY, mgd
7 70
I I
100
700
POPULATION SERVED, thousands
Figure 3-24. Granular media filtration for wastewater
treatment • Net annual operating expenses
(March, 1980 dollars).
m
O o
z =
IE
10
1.0
0,1
.01
0.1
0.7
i
T—T~T
J L.,1 Mill
T—r
I ii if.
1.0 10
SYSTEM CAPACITY, mgd
70
100
700
POPULATION SERVED, thousands
Power requirements depend on system design and
head loss through the filter bed. Both system head
loss and backwash frequency are functions of
hydraulic loading, filter media characteristics,
influent solids concentration, and solids characteris-
tics.
References - Section 3
1 . U.S. Environmental Protection Agency, Cincinnati,
OH. Research Summary. Industrial Wastewater,
EPA-600/8-80-026, June 1980.
2. U.S. Environmental Protection Agency, Office of
Water and Waste Management Washington, DC.
Cost Estimates for Construction of Publicly-
Owned Wastewater Treatment Facilities, Sum-
maries of Technical Data, EPA-430/9-76-01 1 ,
February 10, 1977.
3. The Cost of Clean Air and Clean Water. Senate
Document No. 96-38. U.S. Government Printing
Office, Washington, DC, 1979.
4. Innovative and Alternative Technology Assess-
ment Manual, EPA-430/9-78-009. U.S. Environ-
mental Protection Agency, Office of Water and
Waste Management, Washington, DC, February
1980,260pp.
5. Smith, C.V. and D. DiGregorio. Advanced
Wastewater Treatment in Chemical Engineering,
Deskbook Issue, April 27, 1970. pp. 71-74
45
-------
6. Sage Murphy Associates. Construction Costs for
Municipal Wastewater Treatment Plants, 1973-
1978, EPA-430/9-80-003. U.S. Environmental
Protection Agency, Office of Water and Waste
Management, Washington, DC.
7. Metcalf and Eddy, Inc. Wastewater Engineering.
McGraw-Hill, New York, NY. 1972.
8. Azad, H.S. (Ed.) Industrial Wastewater Manage-
ment Handbook. McGraw-Hill, New York, NY,
1976.
9. Metcalf and Eddy, Inc. Wastewater Engineering:
Treatment, Disposal, Reuse. McGraw-Hill, New
York, NY, 1979. pp. 583.
10. Eckenfelder, W.W. Industrial Water Pollution
Control. McGraw-Hill, New York, NY, 1966.
11. Parker, C.L. Estimating the Cost of Wastewater
Treatment Ponds. Pollution Engineering, 7(11):
32-37, November 1975.
12. Gulp, R.L., et al. Handbook of Advanced Waste-
water Treatment, Van Nostrand Reinhold Co.,
New York, NY, 1978.
13. Reed, S.C.,etal. Cost of LandTreatment Systems.
EPA-430/9-75-003, U.S. Environmental Protec-
tion Agency, Washington, DC, Office of Water
and Waste Management, September 1979.
14. U.S. Environmental Protection Agency, Cincinnati,
OH. Process Design Manual for Phosphorus
Removal, EPA-625/1 -76-001 a(PB259150*).
15. U.S. Environmental Protection Agency, Cincinnati,
OH. Process Design Manual for Suspended
Solids Removal. EPA-625/1 -75-003a (PB259147*),
January 1975.
16. U.S. Environmental Protection Agency, Cincinnati,
OH. Nitrification and Denitrification Facilities;
Wastewater Treatment, EPA-625/4-73-004a
(PB259447*), August 1973.
17. Gumerman, R.C., et al. (Culp/Wesner/Culp)
Estimating Water Treatment Costs, Vol. 1.
Summary, EPA-600/2-79-162a (PB80-139819*).
U.S. Environmental Protection Agency, Cincinnati,
OH, August 1979.
18. Gumerman, R.C., et al. (Culp/Wesner/Culp)
Estimating Water Treatment Costs, Vol. 2. Cost
Curves Applicable to 1-200 mgd Treatment
Plants, EPA-600/2-79-162b(PB80-139827*).
U.S. Environmental Protection Agency, Cincinnati,
OH, August 1979.
19. U.S. Environmental Protection Agency, Cincinnati,
OH. Process Design Manual for Upgrading
Existing Wastewater Treatment Plants, EPA-
625/1-74-004a (PB259148*), October 1974.
"Available for purchase from the National Technical Information Service,
5285 Port Royal Road, Springfield, VA 22161.
46
-------
Section 4
Particulate Matter Collection
This section reports total capital investment, net
annual operating expenses, and unit annualized
costs for common systems used to remove pa rticu late
matter from gas streams. Particulate matter is one of
the designated air pollutants recognized by the Clean
Air Act that is regulated at the federal, state, and in
some cases the local level. Particulate matter control
is expected to continue to account for a significant
fraction of the total expenditures for air pollution
abatement. Between 1976 and 1982, for example,
roughly half of the total investment expenditures for
air pollution control are estimated to be for the
purchase and installation of particulate matter
control equipment (1).
For 1978, the total nationwide emissions of
particulate matter were estimated at about 14 million
tons, with 4.2 million tonsfrom stationary combustion
sources, 6.8 million from industrial processes, and
the remainder from transportation and other sources
(2). Fuel combustion emissions accounted for 33
percent of all particulate emissions, and electric
utilities accounted for more than half of the fuel
combustion emissions. The crushed stone, sand, and
gravel industries accounted for 26 percent of the total
particulate emissions (3). Although the current
emissions profile probably differs somewhat from the
1978 profile, the data illustrate the relative
magnitude of contributions from various industries.
The total amount of particulate matter controlled by
industry, excluding utilities, has been reported as
about 40 million tons in 1978 (4).
Particulate matter emissions vary in particle size from
submicron particles (less than 1 //m in diameter) to
particles greater than 200 //m in diameter. Larger
particles that comprise the greatest mass fraction of
the emissions are the easiest to collect. Smaller
inhalable particles (less than 15 //m) and respirable
particles (less-than 3 jjm) are more difficult and costly
to capture.
The four systems considered in this report are:
mechanical collectors, electrostatic precipitators
(ESP's), fabric filters, and wet scrubbers. Collection
efficiencies and ranges of costs associated with these
systems are compared in Table 4-1. Although other
processes are available for particulate matter
capture, this report considers only those systems that
are widely used and which have been demonstrated
to be capable of achieving removal efficiencies of at
least 90 percent. Mechanical collectors (cyclones and
multitube cyclones) have been used extensively to
control particulate matter emissions, but their control
efficiencies of 50 to 90 percent are lower than
required by the more restrictive regulations for most
applications. Mechanical collectors are often used for
preliminary treatment in combination with other
control systems. Multitube cyclones, which are more
efficient than single tube cyclones, may find
application as final particle collection devices in some
situations.
The systems considered in this report can be
categorized by the form in which the captured
particulate material is removed from the collection
Table 4-1. Comparison of Major Particulate Collection Systems
Control system
Multitube cyclone
Electrostatic
precipitator
Fabric filter
Wet scrubber
(venturi)
Overall efficiency
percent
50-90
80-99.5+c
95-99.9"
75-99+
Air flow rate
range3
acfm
10,000-1,000,000+
10,000-1,000,000+
10,000-1,000,000+
1,000-100,000+
Unit total
capital investment
dollars/ acfm
3-7
18-24
10-23
6-12e
Unit annu-
alized costb
cents/acf
0.0004-0.0006
0.0006-0.006
0.001 -0.003
0.0007-0.0048
"Conversion factors to express air flow rate in other capacity units: 106 Btu heat input = 412 acfm; MWe output = 3200 acfm. The ranges of
flow rates reflect the ranges of flow rates for which data were available for use in this report.
bUnit annualized costs are based on cost estimates presented in this report. The unit annualized cost accounts for all annual cash expenses
and capital charges per unit of capacity.
cMost ESP's sold today are designed for 98 to 99.5% collection efficiency.
"Fabric filter collection efficiency is normally above 99.5%.
The range for these costs is 10,000 to 100,000 acfm.
47
-------
device. Wet scrubbers remove particles by contacting
the gas stream with liquid, usually water, resulting in
a slurry, or sludge, while cyclones, fabric filters, and
ESP's remove particles directly from the gas in a dry
form. Although some ESP's collect wet aerosols and
fumes such as low-strength sulfuric acid mist or oil,
these ESP's are not considered in this report because
they are not widely used. Some advantages and
disadvantages of wet and dry paniculate matter
removal systems are summarized in Table 4-2.
The overall performance of a given paniculate matter
collection system depends to a large extent on the
specific characteristics of the paniculate matter,
particle size distribution, and the inlet gas stream
paniculate matter concentration. Figure 4-1 illustrates
a typical relationship between removal efficiency and
particle size. Fabric filters and ESP's exhibit high
collection efficiencies for particles smaller than 3//m.
But as shown in Figure 4-1, wet scrubber collection
efficiencies decrease significantly for smaller
particles. Fabric filters generally offer the greatest
potential for removing submicron particles or fines.
Electrostatic precipitators are somewhat less
efficient in removing fines, while high efficiency
cyclones are the least efficient for these very small
particles.
Table 4-2. Comparison of Wet and Dry Collection Systems
Dry collection systems
Wet collection systems
Advantages
Disadvantages
(1) Collected paniculate
matter weighs less than
wet collected panicu-
late matter and is there-
fore less costly to dis-
pose of
(2) Usually requires less
treatment for disposal
(3) Allows for participate
matter recovery tn
some cases
(4) Usually no serious
corrosion problem
(1) Inability to collect
mists and hygroscopic
or caking materials
(2) Potential to create dust
emissions in handling
collected paniculate
matter
(1) Ability to collect
mists and aerosols
(2) Ability to collect
gaseous pollutants in
addition to particulate
matter
(1) May require wastewater
and sludge treatment
lor disposal
{2} Potential to discharge
droplets of scrubbing
liquor with entrained
contaminants to the
atmosphere
The performance of most fabric filter systems is not as
strongly affected by changes in the inlet gas
particulate matter concentration, as with ESP's, wet
scrubbers, and mechanical collectors. With the latter
devices, the outlet particulate matter concentration is
directly related to the inlet particulate matter
concentration.
Table 4-3 illustrates the effect of inlet concentration
and emission concentration on required collection
efficiency. The specified controlled emission concen-
trations represent, typical new source performance
standards and concentrations required by typical
state regulations for existing sources. This table
illustrates the levels of collection efficiencies for
Figure 4-1. Illustration of collection efficiency versus
particle diameter (5).
A = Fabric Filter
B = Hotside ESP
C = Coldside ESP
D = Venturi Scrubber, AP = 100 in. H2O
E = Venturi Scrubber, AP = 20 in. H2O
F = Venturi Scrubber, AP = 10 in. H2O
G = Multitube Cyclone
H = High Efficiency Single-tube Cyclone
UJ
O
LL
U.
HI
Z
g
o
UJ
_j
_i
o
o
.05 0.10 0.5 1.0
PARTICLE DIAMETER, um
10
Table 4-3.
Required Collection Efficiency for Typical
Uncontrolled and Hypothetical Controlled
Particulate Matter Concentrations
Inlet gas stream
uncontrolled
particulate matter
concentration
gr/acfa
0.5
2.0
5.0
20.0
Outlet gas stream
controlled
particulate matter
concentration
gr/acf1*
0.01
0.05
0.20
0.01
0.05
0.20
0.01
0.05
0.20
0.01
0.05
0.20
Required
control
efficiency
%
98.00
90.00
60.00
99.50
97.50
90.00
99.80
99.0O
96.00
99.95
99.75
99.00
agr/acf = grains per actual cubic foot. This is a common unit for
expressed particulate matter concentrations. There are 7,000
grains to 1 pound.
"Outlet concentrations required by regulations for some sources
include: grain elevators, 0.01 gr/acf; metals industry, 0.022
gr/acf; utility coal-fired boilers, 0.03 gr/acf.
which most particulate matter systems must be
designed.
Individual technologies and costs are described in the
following sections.
48
-------
4.1 Multitube Cyclones
Description
Cyclones use the principle of centrifugal separation to
collect particulate matter in a dry form. There are two
basic types of cyclones: single-tube cyclones and
multitube cyclones. Multitube cyclones consist of a
number of individual small diameter conically tapered
tubes arranged in a common housing and operated in
parallel. Spin vanes in each vertical tube of the
multitube cyclone impart a high rotational velocity to
the entering gas stream. As the gas stream spirals
downward through the tubes, centrifugal forces
impel the suspended particles toward the walls of the
tubes. The particles fall from the open bottoms of the
tubes into collection hoppers when the gas flow
makes a sharp directional change upward at the
bottom of each tube. From the collection hoppers the
dust particles are transfered to storage, and
ultimately, to disposal or recycle. The cleaned gas
exits through the top of each tube into the outlet
plenum and then to the stack.
Compared to single-tube cyclones, multitube
cyclones achieve greater particle removal efficiencies
without significantly increasing resistance to gas
flow. Multitube cyclones may thus be used to meet
particulate emission control requirements in some
applications. However, the less efficient single-tube
cyclones are usually unsuitable for this purpose and
are thus not discussed in.this report.
Complete multitube cyclone systems include the
major components shown in Figure 4-2.
The efficiency of multitube cyclones depends mainly
on the inlet gas velocity, the diameter and length of
individual tubes, and most importantly, the range of
particle sizes in the entering gas stream. Higher inlet
gas velocities, smaller tube diameters, and longer
tube lengths increase particle removal efficiency but
also increase resistance to gas flow. As was shown in
Figure 4-1, smaller particles are collected less
efficiently than larger particles. The overall collection
efficiency thus depends on the relative proportions of
small and large particles. Efficiencies achieved in
various cyclone applications for emissions control
vary from about 55 to 95 percent. Applications
include removal of fly ash from coal-fired boilers and
dust control in minerals processing.
Design Basis and Costs
The principal variables in the design of multitube
cyclone systems are: gas flow rate, inlet particulate
matter concentrations, particle size distribution,
desired particle removal efficiency, and potential
need for corrosion or erosion resistant materials. The
design characteristics (such as tube diameter and
inlet gas velocity) of the cyclone depend on all of the
listed design variables. The size of the associated
ductwork depends on the gas flow rate. Fan size
depends on the gas flow rate and the system pressure
drop (which depends on resistance to the gas flow).
The particulate matter inlet concentration and the
Figure 4-2. Multitube cyclone system for Particulate matter collection.
Inlet
Particulate
Laden Gas
System Boundary
Cleaned Gas
to Discharge
Stack
Dust to
Disposal
by Landfill'
*lf the dust is valuable, it may be recovered as product or for recycle. The costs in
this report assume that the dust is disposed of as landfill.
49
-------
particle removal efficiency determine the quantity of
dust removed and thus determine the size and type of
dust removal system.
Table4-4 presents the design parameters for the
multitube cyclone systems used to develop the cost
curves presented in this section. The cyclone design
characteristics and inlet paniculate matter concen-
tration typify multitube cyclone applications on coal-
fired boilers.
Total capital investment data are presented in Figure
4-3. Net annual operating expenses are shown in
Figure 4-4, and unit annualized costs are shown in
Figure 4-5.
The capital investment data were developed by
updating the correlating cost data from the following
references: multitube cyclone costs (7); fan and motor
costs (8); ducting costs (9); and dust removal costs
(10). Net annual operating expenses and unit
annualized costs were developed from data in
Reference 9.
Major Variables Affecting Costs
The investment cost of the multitube cyclone itself is
usually less than half of the capital investment of the
total multitube cyclone system. In the system
considered in this report, the multitube cyclone cost is
only 17 to 43 percent of the system cost, with a
proportionately greater share for the larger systems.
Significant variations in the multitube cyclone
characteristics (such as tube diameter) thus may not
significantly affect system costs.
The fan and motor cost comprises 8 to 22 percent of
the investment costs for the systems considered in
this report. For the larger systems, the fan and motor
cost is the largest element of the investment.
Table4-4. Multitube Cyclone Design Parameters
Parameters
Gas flow rate, acfm
Inlet loading, gr/acf
Overall particle Removal
Efficiency, %
Pressure drop, in. HjO
Operating pressure
Tube diameter, in.
Tube length, ft
Materials of construction
Dust removal and storage
-1,000 and 10,000 acfm
-100,000 and 1,000,000 acfm
Dust disposal
Ducting, ft
Operating factor, %
Equipment life, years
"Up to about 100,000 acfm for
require multiple units.
"Unknown or not specified.
cReference 6.
Design basis Typical range
10,000; a
100,000; 1,000,000
20 h
•_,<_- u
85 sc_qq+c
**** J*J-JJT
3 7-fic
w f, V
Atmospheric b
9 6-24c
b h
" U
Carbon Steel Carbon Steel
Dumpster Site-specific
pneumatic conveying/ Site-specific
storage silo
Landfill Landfill, bonding.
or recycle
*00 Site-specific
70 Site-specific
20 b
single multitube units. Higher gas flows
The cost of ducting ranges from about 12 to 46 percent
of the investment costs for the systems considered in
this report. For the smaller systems, the ducting cost
is the largest element of the investment.
The cost of the ash removal and storage system
ranges from about 19 to 60 percent of the investment
costs, with the greater share for intermediate-sized
systems.
The major contributors to net annual operating
expenses are: dust disposal costs, electricity for the
fan, labor, and maintenance costs. Electricity and
dust disposal costs are a much more significant
portion of total costs for the large systems than small
systems. Electricity costs are up to about 20 percent
of the net annual operating expenses. Dust disposal
costs comprise 50 to 65 percent of the expenses.
Thus, net annual operating expenses can be
significantly reduced if ultimate disposal costs can be
reduced or credits can be taken for recovered useable
material.
4.2 Electrostatic Precipitators
Description
Electrostatic precipitators (ESP's) are used to remove
paniculate matter from waste gases in a variety of
industrial applications. Industries and emission
Figure 4*3. Multitube cyclone system for particulate matter
collection - Total capital investment (March,
1980 dollars).
L INVESTMENT
of dollars
b
Q..O
Of 0.1
t-
o
F-
.01.
i i i IMTF
-
-
- , thu,
I I T [HI
/
/
/
I I I |IUL
/
' \
-
-
10 100 10C
GAS FLOW, thousand acfm
10 100
GENERATING CAPACITY, MWe
10
100
1000
I
FIRING RATE, 106 Btu/hr
50
-------
Figure 4-4. Multitube cyclone system for paniculate matter
collection - Net annual operating expenses
(March, 1980 dollars).
CO
LJJ
w
z
tlJ-o
O o
-------
Figure 4-6. Electrostatic precipitator system for paniculate matter collection.
Inlet
Particulate
Laden Gas
Electrostatic
Precipitator
System Boundary
Cleaned
Gas to
Discharge
Stack
Dust to
Disposal
by Landfill1
for
The
Design Basis and Costs
The scope of the ESP systems discussed in this
section is illustrated in Figure 4-6. Equipment or
operations shown by solid lines in Figure 4-6 are
included in the scope of ESP systems. The fan shown
by dashed lines is not included in the scope of ESP
systems. This is because ESP pressure drop is
relatively small, and the installation of an ESP on a
source already requiring a fan will not result in a
significant alteration in fan requirements.
The principal variables in the preliminary or
conceptual design of ESP systems are- inlet
paniculate matter loading, desired removal efficiency
particle size distribution, particle electrical resistivity
{affected by the gas composition and temperature as
well as particle composition), gas flow rate and
distribution, and materials of construction The
particle inlet loading, gas flow rate, and removal
efficiency determine the quantity of dust removed
and thus determine the size and type of dust removal
system needed. The particle sizes and resistivity
determine the ease with which a specific paniculate
matter precipitates and thus affects ESP design As
with other gas handling equipment, flow rate also
affects ESP design and the size of associated
ductwork. If the gas is corrosive, then higher-price
corrosion-resistant materials must be incorporated
into the system.
Classically, ESP's have been sized from the Deutsch-
Anderson equation for preliminary or conceptual
designs:
- 1 - exp
[••H
(4-1)
where r) =desired removal efficiency, expressed as
a fraction
A=collecting electrode plate area (the prin-
cipal ESP design parameter), ft2
V=gas volume flow rate, ftVs
w =precipitation rate parameter, ft/s
The precipitation rate parameter, u, is determined
from experience for specific applications and
accounts for differences in particle sizes and
resistivity from one application to another. The
physical significance of u is to describe the average
rate at which charged particles will migrate toward
the collecting electrodes. Lower values of cj denote
more difficult precipitation applications such as the
precipitation of high resistivity fly ash from low sulfur
coals. Table 4-5 shows the range of precipitation rate
parameters encountered in typical ESP application.
Table 4-6 presents the design parameters for 12 case
study ESP's used to develop the cost curves
presented in this section. The only constant design
variable for these ESP's is the inlet particle loading
which at 2.0 gr/acf, typifies flue gases from coal-fired
boilers, lime kilns, and other sources. Higher loadings
results in larger and more expensive ash disposal
systems and also increase the cost of ultimate
disposal. The potential impact of higher loadings is
addressed in the discussion of major variables
affecting costs. High loadings could also adversely
affect the precipitation rate.
Figure 4-7 shows the total capital investment
^U™d for ESP'S used in applications ranging from
100,000 to 1,000,000 acfm as a function of two major
design variables: the ease of precipitation, and the
required particle removal efficiency. In using Figure
52
-------
Table 4-5. Precipitation Rate Parameters for Typical ESP Applications3
Precipitation rate parameters, fps
Emission source or
industry category
Coal-fired boilers
Pulp and paper industry
Cement industry
Gypsum industry
Iron and steel industry
-sintering
-open-hearth furnace
-basic oxygen furnace
-electric arc furnace
-blast furnace
-gray iron cupola
Municipal waste
incinerators
Glass manufacturing
Phosphate rock crushing
Lime industry
Copper smelters
Other smelters
Petroleum cat cracking
Range
0.10-0.67b'c'd'e
0.2-0.35b'c
0. 1 9-0.45c'd
0.4-0.64°-"
0.08-0.4°
0.15-0.3C
0.15-0.25C
0.12-0.16C
0.20-0.46°
0.10-0.12M
0.2-0.4°
—
—
0.17-0.25e
0.12-0.14C
—
0.12-0.186
Average
or typical
0.35'
0.25M
0.30'
0.52'
0.27'
0.21*
6.20'
0.14*
0.37'
0.10"
0.3'
0.1 4e
0.35e
0.259
0.13'
0.25c'd
0.15*
Difficulty of
precipitation"
Difficult to easy
Average
Difficult to average
Average to easy
Difficult to average
Difficult to average
Difficult to average
Difficult
Average
Difficult
Average
Difficult
Average
Difficult to average
Difficult
Average
Difficult
*The precipitation rate parameter has classically been used in the Deutsch-Anderson equation to predict ESP performance in various
applications. Although it can be assumed constant some applications, the precipitation rate parameter will actually vary in given applica-
tion as a function of collection efficiency. Use the of Deutsch-Anderson equation to design (size) highly efficient ESP's requires using a con-
servative (low) precipitation rate parameter. For example, the precipitation rate parameter for an ESP on one coal-fired boiler 0.43 fps
for a 92% removal and 0.16 fps for a 99.5% removal. (Reference 1)
"Reference 11
Reference 12
°Reference 13
"Reference 8
'Estimate
9Reference 14
"Difficult = Precipitation Rate Parameter <0.20 fps
Average = Precipitation Rate Parameter XX20 fps, <0.50 fps
Easy = Precipitation Rate Parameter XX50 fps
Table 4-6. Design Parameters for Model Electrostatic Precipitators3
Ease of
precipitation
1. Difficult
2. Difficult
3. Difficult
4. Difficult
5. Difficult
6. Difficult
7. Typical
8. Typical
9. Typical
10. Typical
1 1 . Typical
12. Typical
Precipitation
rate parameter Mb
fps
0.10
0.10
0.10
0.10
0.10
0.10
0.30
0.30
0.30
0.30
0.30
0.30
Gas flow rate
acfm
10,000
10,000
100,000
1 00,000
1 ,000,000
1 ,000,000
10,000
10,000
100,000
100,000
1 ,000,000
1 ,000,000
PM removal
efficiency
%
95
99.9
95
99.9
95
99.9
95
99.9
95
99.9
95
99.9
Collecting electrode
surface area0
ft2
4.990
11,500
49,900
1 1 5,000
499,000
1.150,000
1,660
3,840
16,600
38,400
1 66,000
384,000
PM removal
rate
Ib/hr
163
171
1,630
1,710
1 6,300
17,100
163
171
1,630
1,710
1 6,300
17,100
aAII 12 model ESP's have the following additional characteristics: (1) Inlet dust loading -
Equipment lifetime = 20 years, (4) Power demand = 3.5 W/ft2 of collecting electrode area
construction. The 10,000 acfm systems feature ash removal and storage in a dumpster. The
of ash to silos for storage.
^The collecting electrode surface area is estimated from the Deutsch-Anderson equation:
77 - 1 - exp - _^_ w
V
where r} = PM removal efficiency
A-Collecting electrode surface area, ft2
V=Gas flow rate, ftVsec
o>-Precipitation rate parameter, fps
2.0 gr/acf, (2) Operating factor = 70%, (3)
, (5) Duct length = 200 ft, and (6) Mild steel
larger systems feature pneumatic conveying
53
-------
Figure 4-7. Electrostatic precipitator system for particulate
matter collection • Total capital investment
(March, 1980 dollars).
Difficult Precipitation; 99.9% removal
(e.g., Low S Coal with High Resistivity Fly Ash)
Difficult Precipitation; 95.0% removal
(e.g., LowS Coal with High Resistivity Fly Ash)
Typical Precipitation; 99.9% removal
(e.g., High S Coal with Low Resistivity Fly Ash) ._._._
Typical Precipitation; 95.0% removal
(e.g., High S Coal with Low Resistivity Fly Ash) ,
100
10
LLJ .55
11
CL g
5= 1.0
0.1
10
100 1000 10,000
GAS FLOW RATE, thousand acfm
10
100
I
1000
GENERATING CAPACITY, MWe
100 1000 10,000
I I I
FIRING RATE, 1Q6 Btu/hr
4-7 (and Figures 4-8 and4-9), the user should refer to
Table 4-5 to determine the ease of precipitation (i.e.,
the precipitation rate parameter) for the application of
interest.
Net annual operating expenses are shown in Figure
4-8, and unit annualized costs are presented in Figure
4-9.
The capital investment cost curves are developed
from statistical correlations of study^estimatesofthe
various ESP subsystems from References 8,10,14,
15, and 16. The subsystems are the ESP, ducting, and
a solids disposal system. The ducting and solids
disposal subsystem costs were estimated using
correlations based on the costs presented in two
references (10, 15). The net annual operating
expense curves are derived from References 10,14,
15, and 16.
Major Variables Affecting Costs
As discussed previously, high particulate matter
concentrations result in larger and more expensive
Figure 4-8. Electrostatic precipitator system for particulate
matter collection • Net annual operating expenses
(March, 1980 dollars).
Difficult Precipitation; 99.9% Removal
(e.g., Low S Coal with High Resistivity Fly Ash)
Difficult Precipitation; 95.0% Removal
(e.g., LowS Coal with High Resistivity Fly Ash)
Typical Precipitation; 99.9% Removal
(e.g., High S Coal with Low Resistivity Fly Ash) „_
Typical Precipitation; 95.0% Removal
(e.g., High S Coal with Low Resistivity Fly Ash)
100 1000
GAS FLOW, thousand acfm
10,000
10
100
I
1000
GENERATING CAPACITY, MWe
100
1000
10,000
I
FIRING RATE, 106 Btu/hr
dust collection systems and increase the cost of
ultimate disposal. High concentrations may also
adversely affect the precipitation rate and require a
larger, more expensive ESP. A higher particle
concentration that increases the capital investment
of an ash removal system by 100 percent increases
the total capital investment up to 25 percent
depending on overall system size. A 100 percent
increase in the cost of ultimate solids disposal can
increase the net annual operating expenses by as
much as 50 percent, again depending on overall
system size. There is a relatively higher percentage
impact on larger systems.
For some applications, a fraction of the recovered
solids can be recycled. As illustrated above, net
annual operating expenses can be significantly
reduced if ultimately disposal costs can be reduced or
credits taken for recovered usable material. Such
evaluations must be made on a case-by-case basis.
Although the cost curves in Figures 4-7 through 4-9
are based mainly on data for ESP's applied to coal-
54
-------
Figure 4-9. Electrostatic precipitator system for participate
matter collection • Unit annualized cost (March,
1980 dollars).
Difficult Precipitation; 99.9% Removal
(e.g., Low S Coal with High Resistivity Fly Ash) ——_
Difficult Precipitation; 95.0% Removal
(e.g., LowS Coal with High Resistivity Fly Ash) —
Typical Precipitation; 99.9% Removal
(e.g., High S Coal with Low Resistivity Fly Ash) -. — • — .-
Typical Precipitation; 95.0% Removal
(e.g., High S Coal with Low Resistivity Fly Ash)
8|
0 5
m cO
N 2>
h- "c
— 0)
2 O
100 1000 10,000
GAS FLOW, thousand acfm
10 100 1000
——i 1 i
GENERATING CAPACITY, MWe
100 1000 10,000
—i i i
FIRING RATE, 106 Btu/hr
fired boilers, they are applicable to ESP's for other
emission sources if the inlet grain loading and other
design parameters are similar.
4.3 Fabric Filters
Description
Fabric filters are widely used to control dry paniculate
matter emissions in a variety of industrial applications,
whenever dry bulk solids are processed, especially in
processsing metals, minerals, and grains. Fabric
filters are also .becoming more widely used on coal-
fired boilers.
Fabric filtration is the physical straining or sieving of
paniculate matter from gas streams. The gas stream
passes through a fabric filter medium (usually in the
shape of a bag). Paniculate matter from the inlet gas
deposits mainly on the surface of the filter bag, where
a dust layer accumulates. Both the collection
efficiency and the pressure drop across the bag
surface increase as the dust layer builds up. When
the pressure drop becomes excessive the bags are
cleaned to remove collected solids which are then
disposed of.
The collection efficiency of fabric filters is primarily
dependent on the characteristics of the fabrics used
and paniculate matter (particle size distribution and
cake porosity) and is not dependent to any noticeable
extent on the amount of collection fabric surface area.
However, the fabric surface area does affect pressure
drop and hence the energy requirements.
Filters are generally cleaned in one of three ways. In
shaker cleaning, the filter bags are oscillated by a
small electric motor. The oscillation dislodges varying
amounts of dust into a hopper depending on the
shaking frequency and amplitude. In reverse air
cleaning, a reverse air flow is used to collapse the
bags, and fracture and dislodge the dust cake. Both
shaker cleaning and reverse air cleaning require a
sectionalized baghouse to permit cleaning of one
section while other sections are functioning normally.
The third cleaning method, pulse jet cleaning, does
not require sectionalizing (with some dusts, section-
alization may be preferred for pulse jet cleaning). A
short pulse of compressed air is delivered through
nozzles at the bag exit and is directed toward the
bottom of each bag. The primary pulse of air entrains
a pulse of secondary air flow as it passes through the
nozzles. The resulting pressure produces a shockthat
expands the bag and dislodges the surface dust layer.
Although all three basic cleaning methods, singly or
in combination, are used, only reverse air and pulse
jet cleaning methods are discussed in this report.
Reverse air cleaning appearsto be preferred for larger
applications while pulse jet cleaning appears to be
preferred for smaller applications. Shaker cleaning is
most suitable when the filtration medium will not
degrade due to mechanical stresses.
Figure 4-10 is a conceptual diagram of a typical fabric
filter installation. Fabric filter systems consist of four
major components: a baghouse {containing the fabric
filter bags), ducting, a booster fan, and a solids
removal system.
The complexity of a fabric filter system depends to a
large degree on the quantity of solids to be collected.
Small fabric filter systems typically discharge
collected solids directly from baghouse hoppers to
dumpsters; the solids are ultimately disposed of by
landfilling. Large fabric filter systems typically feature
either a pneumatic dust removal system which
transfers dust to a storage silo and ultimate disposal,
or wet sluicing to water treatment and ultimate
disposal. The collected dust could also be recovered
as product or for recycle.
Fabric filter systems are sometimes preceded by gas
pretreatment or conditioning processes. Precleaning
is usually accomplished with mechanical collectors.
Since most common filter fabrics are limited to
temperatures below 550°F (with some fabrics li mited
55
-------
Figure 4-10. Fabric filter system for participate matter collection.
Inlet
Particulate
Laden Gas
System Boundary
Cleaned
Gas to
Discharge
Stack
Dust to
Disposal
by Landfill'
'If the dust is valuable, it may be recovered as product or for recycle. The costs
in this report assume that the dust is disposed of as landfill.
to temperatures below 1 75°F), the gas stream can be
cooled either directly by quenching the gas with
water or by indirect cooling. The temperature must be
maintained high enough, however, to prevent
moisture condensation within the baghouse and on
the filter surface. Moisture causes the collected
particles to agglomerate and plug the bags.
Particulate matter removal efficiencies of greater
than 99.9 percent are achieved in many applications,
with paniculate matter concentrations in the filtered
gas usually less than 0.04 gr/ft3. Fabric filters can
effectively control fine particulates and usually
require only moderate pressure drop across the
control system. Fabric filter performance is relatively
unaffected by flue gas composition, inlet paniculate
matter concentration, and particle composition and
properties.
Design Basis and Costs
The principal variables in the design of fabric filter
systems are: gasflow rate, bag cleaning method, filter
bag surface area, inlet paniculate matter concentration
and size properties, potential need for corrosion
resistant and heat-resistant materials, gas tempera-
ture, and gas moisture content. The required filter
area for a specific application depends on the gas flow
rate, the bag cleaning method, and characteristics of
the dust. The sizes of associated ductwork andfan are
also dependent on the gas flow rate. The paniculate
matter inlet concentration determines the quantity of
dust removed and thus determines the size and type
of solids removal system. High inlet particulate
matter concentrations may also affect the filter area
or require precleaning.
The most important design variables, the bag
cleaning method and fabric filter area, are determined
from experience in similar applications. Although
either reverse air cleaning or pulse jet cleaning may
be used for most applications, a specific cleaning
method may be preferred. Pulse jet cleaning allows
the use of sma Her fabric filter areas than does reverse
air cleaning.
For a specific application, bag material, and bag
cleaning method, the required filter area is determined
from the gas flow rate and the air-to-cloth ratio
demonstrated by experience to be most suitable and
economical. The air-to-cloth ratio is the ratio of the
gas flow rate to the filter area and is typically
expressed as actual cubic feet per minute per square
foot (acfm/ft2) or feet per minute (fpm). The air-to-
cloth ratio for baghouses using reverse air cleaning
averages 2 fpm with a range of 1.5 to 3.5 fpm. The air-
to-cloth ratio for baghouses using pulse jet cleaning
averages 6 fpm with a range of 4 to 15 fpm (13,17).
Table 4-7 presents the design parameters for five
case study fabric filter systems used to develop the
cost curves presented in this report. The inlet
particulate matter concentration of 2 gr/ft3 assumed
for these systems is representative of flue gases from
coal-fired boilers (10, 11, 12, 14, 15). The potential
cost impacts of higher or lower air-to-cloth ratios and
inlet particulate matter loadings are addressed in the
discussion of major variables affecting costs.
Total capital investment is presented in Figure 4-11.
Net annual operating expenses are shown in Figure
4-12, and unit annualized cost estimates are shown
in Figure 4-13.
The capital investment curves are derived from
study estimates reported in References 8,10,14, and
16. The cost curves are developed from statistical
correlations of the estimated costs of the various
56
-------
fabric filter subsystems: baghouse and filter bags,
ducting, fan, and solids removal system. The ducting
and solids disposal subsystem costs are based on
correlations derived from costs for these subsystems
in References 10 and 16.
Table4-7. Design Parameters for Model Fabric Filter
Systems3
Gas flow rate
acfm
10,000
100,000
1 ,000,000
Participate
matter
removal rate
Ib/hr
170
1,700
1 7,700
aAII model fabric filter systems have the following additional
characteristics: (1) Reverse-air air-to-cloth ratio=2 fpm, (2) Pulse-
jet air-to-cloth ratio = 6 fpm, (3) Inlet dust concentration = 2.0
gr/scf, (4) Outlet dust concentration = 0.02 gr/acf or less, (5)
Operating factor = 70%, (6) Equipment lifetime = 20 years, (7) Bag
lifetime = 2 years, (8) Duct length = 200 ft, and (9) Mild steel
construction with insulation. The reverse-air systems are
assumed to operate at high temperature (<550°F) and use fiber-
glass bags. The 10,000 acfm system features ash removal and
storage in a dumpster. The 100,000 and 1,000,000 acfm systems
feature ash removal in a pneumatic conveying system and storage
in a silo.
"The air-to-cloth ratio (A/C) and the gas flow rate (A) determine the
required fabric filter area (C) since C = A/(A/C).
Figure 4-11. Fabric filter system for paniculate matter
collection • Total capital investment (March,
1980 dollars).
Curves based on reverse air cleaning with air-to-cloth ratio
of 2:1. Pulse jet cleaning with air-to-cloth ratio of 6:1
costs 36% less at 10,000 acfm and 22% less at 100,000
acfm. Costs for pulse jet systems do not extend beyond
100,000 acfm.
100
LU
5
yj£ 10
UJ JO
D_ O
< =
Oc 1.0
0.1
T—1 I I M M
1 MINI
1 1 I II I I.
10 100 1000 10,000
GAS FLOW RATE, thousand acfm
10
100
I
1000
GENERATING CAPACITY, MWe
100 1000 10,000
_J I I
FIRING RATE, 106 Btu/hr
Figure 4-12. Fabric filter system for participate matter
collection • Net annual operating expenses
(March, 1980 dollars).
Curves based on reverse air cleaning with air-to-cloth
ratio of 2:1. Pulse jet cleaning with air-to-cloth ratio of
6:1 costs 9% less at 10,000 acfm and 14% less at 100,000
acfm. Costs for pulse jet systems do not extend beyond
100,000 acfm.
10
in
in
z
"J s
x|
LLI
1.0
Q- »-
O o
_i to
0.1
.01
T—I I HIM
T—I I I I ITT
T 1 I | II I'.
10 100 1000
GAS FLOW, thousand acfm
10 100
10,000
1000
I
GENERATING CAPACITY, MWe
100
I
1000
10,000
I
FIRING RATE, 106 Btu/hr
The net annual operating expense estimates are
similarly based on costs in References 8,10, 14,16,
and 18.
Major Variables Affecting Costs
Pulse jet baghouse systems are generally used in
lower gas flow rate applications than reverse air
baghouses. Since pulse jet cleaning operates at
higher air-to-cloth ratios and smaller filter areas, it is
less expensive than the other cleaning methods.
Pulse jet systems require between 35 and 50 percent
less capital investment than reverse air systems for
applications treating 10,000 and 100,000 acfm. The
net annual operating expenses for pulse jet systems
are up to about 15 percent lower than for reverse air
systems.
As discussed previously, the air-to-cloth ratio is
determined from experience and can range from 1.5
to 3.5 fpm for reverse air cleaning and from 4 to 15
fpm for pulse jet cleaning. The case study fabric filter
systems used to develop cost curves in this report are
based on average or typical air-to-cloth ratios: 2 fpm
for reverse air cleaning and 6 fpm for pulse jet
cleaning. Systems featuring reverse air cleaning with
57
-------
Figure 4-13. Fabric filter system for participate matter
collection - Unit annualized cost (March, 1980
dollars).
Curves based on reverse air cleaning with air-to-cloth ratio
of 2:1. Pulse jet cleaning with air-to-cloth ratio of 6:1
is 17% less. Costs for pulse jet systems do not extend
beyond 100,000 acfm.
100 1000
GAS FLOW, thousand acfm
10,000
10
i
100
_J
1000
GENERATING CAPACITY, MWe
100
1000
10,000
FIRING RATE, 106 Btu/hr
an air-to-cloth ratio of 1 fpm (at a gas flow of 100,000
acfm} typically have total capital investment
requirements about 45 percent higher than systems
designed for an air-to-cloth ratio of 2 fpm, while net
annual operating expenses are about 40 percent
higher. Systems with air-to-cloth ratios of 4 fpm have
total capital investment requirements about 25
percent lower than systems designed for an air-to-
cloth ratio of 2 fpm, while net annual operating
expenses are about 10 percent lower.
High inlet particle concentrations create the need for
larger and more expensive ash disposal systems and
increase the cost of ultimate disposal. Very high inlet
paniculate matter concentrations can also require
increased filter areas or the use of a gas precleaning
process. As an example, an inlet paniculate matter
concentration of 5 gr/acf or 2.5 times that specified
for the model fabric filter systems would typically
increase the capital investment requirement by about
5 percent but would increase net annual operating
expenses by about 40 percent. On the other hand, an
inlet paniculate loading of 1 gr/acf would reduce the
capital investment requirement by about 3 percent
and reduce net annual operating expenses by about
15 percent. If the recovered dust could be recycled
and disposal requirements minimized, annual
operating expenses could be reduced further.
Expected filter bag life also affects costs. A reduction
in bag life from 2 years (the value assumed in the cost
curves) to 6 months would typically increase net
annual operating expenses by up to about 20 percent.
The impact of bag life is greatest on large systems
where the costs of bag replacement are a relatively
greater fraction of operating expenses.
Although the cost curves in Figures 4-11 through 4-
13 are based on fabric filter systems applied to coal-
fired boilers, they can be used for other applications if
the inlet grain loadings, air-to-cloth ratios, and dust
characteristics are similar. Fabric filtration generally
can be used to collect dry particles from any source if
moisture condensation can be avoided.
4.4 Venturi Wet Scrubbers
Description
A venturi wet scrubber is a collection device which
uses an aqueous stream or slurry to remove
particulate matter and/or gaseous pollutants.
Scrubbers are usually classified by energy consump-
tion (in terms of gas-phase pressure drop). Low-
energy scrubbers, represented by spray chambers
and towers, have pressure drops of less than 5 in.
HzO. Medium-energy scrubbers, such as impinge-
ment scrubbers, have pressure drops of 5-15 in. HzO.
Higher-energy scrubbers, such as high-pressure drop
venturi scrubbers, have pressure drops exceeding 15
in. H20. The most common scrubbers used for
'moderate' removals of paniculate matter are
medium-energy impingement and venturi scrubbers.
Greater removals of paniculate matter are usually
achieved with high-energy venturi scrubbers.
The collection efficiency of scrubbers is essentially
dependent on the characteristics of the paniculate
matter (panicle size) and the energy input to the
scrubber (as measured by pressure drop).
Venturi scrubbers have gained widespread popular-
ity, especially for the collection of hygroscopic and
corrosive submicron panicles. In a typical venturi
scrubber, the panicle-laden gas first contacts the
liquor stream in the core and throat of the venturi
section. The gas and liquor streams then pass
through the annular orifice formed by the core and
throat, atomizing the liquor into droplets which are
impacted by particles in the gas stream. Impaction
results mainly from the high differential velocity
between the gas stream and the atomized droplets.
The paniculate laden droplets then are removed from
the gas stream by centrifugal action in a cyclone
separator and, if appropriate, a mist elimination
section.
58
-------
Some major industries which use venturi scrubbers
for paniculate matter control are:
• Coal cleaning industry for emissions from coal
handling systems.
• Phosphate fertilizer industry for emissions from all
major sources except grinding and screening
operations.
• Lime and asphalt plants for emissions from kilns.
• Metal (iron and steel, iron foundries, and
ferroalloy) industries for emissions from various
processing operations.
The equipment normally associated with venturi
scrubber systems is shown in Figure 4-14.
As the particulate matter accumulates in the
circulating scrubber liquid, a fraction of the liquid is
removed and sent to disposal/reuse treatment. Fresh
scrubber liquid is added to the circulating stream to
replace evaporation losses and liquid removed as
blowdown.
Because the pH of the scrubber circulating liquid may
be altered due to the incidental absorption of acidic
gas species such as SOz, or collection of alkaline
species such as lime dust, pH control of the blowdown
liquor that is removed may be required before
discharge.
Factors that affect the performance of typical wet
scrubbers are:
- Gas velocity (or gas phase pressure drop).
- Liquid-to-gas ratio (L/G).
- Particle size distribution.
- Inlet gas particulate matter concentration.
Although the performance of a scrubber depends
directly on both the liquid-to-gas ratio and the gas
velocity, the gas-phase pressure drop is usually the
major factor affecting removal. As shown by Figure4-
15, removal efficiency increases with increasing gas-
phase pressure drop: greater pressure drops (or gas
velocities) create smaller liquid drops that are more
efficient in collecting particulate matter. However,
high-pressure drop scrubbers may show decreasing
removal efficiency with increasing pressure drop due
to carryover of the particulate-laden scrubbing
droplets. High-pressure-drop scrubbers should thus
be equipped with mist eliminators to ensure adequate
separation of gas and scrubbing droplets.
If the liquid rate to the scrubber is sufficient to provide
an adequate distribution of liquid droplets in the gas
stream without flooding the scrubber, scrubber
performance is relatively insensitive to variations in
the liquid-to-gas ratio. Increases in the liquid-to-gas
ratio generally increase scrubber efficiency, but the
performance increases are usually small.
As shown in Figure 4-15, scrubber performance
depends on the particle size distribution of the
particle matter to be collected. This figure shows
that collection efficiency varies directly with particle
size, with larger particles collected at greater
efficiency.
Figure 4-14. Venturi wet scrubber system lor particulate matter collection.
Particulate
Laden Gas
Makeup*.
Liquid
Droplet
Deentrainment
Vessel
H
Reheat
I I
Waste Treatment
and Disposal
System Boundary
Scrubbed
Gas
*The amount of makeup added or liquor removed depends on the liquid losses due
to evaporation into the gas stream, and the accumulation of dissolved solids in the
reclrculating liquid.
59
-------
Figure 4-15. Venturi wet scrubber comparative fractional
efficiency curves. (19)
AP = 35-40 in. H2O
AP = 25-30 in. H2O
AP = 14-16 in. H2O
AP = 11-12 in. H2O
AP = 8-9 in. H2O
O
•z.
UJ
O
LL
LL
UJ
O
UJ
O
O
99.95
99.90
99.80
99.50
99.00
98.00
95.00
90.00
80.00,
X
X
'' s
/
^
^ .•
•"" .•**
^ .*•*
/
X
*'
/
^
^
^ .-*
•S ..*
-"" r'
**
x
X X
.X ^
XX
s' S
•S .•'
^ ,.*
s- .•*
s f.*'
s
xi
' X
tr
s*
s- ,.*•*
u-3 1-0 2.0 5.0 10
PARTICLE DIAMETER, ym
Scrubber performance also depends on the paniculate
matter inlet concentration. Concentrations exceeding
the scrubber design loading could overload the
scrubber and reduce paniculate matter removal
efficiency. Scrubber efficiency could be improved by
increasing the gas velocity (or pressure drop) and
liquid-to-gas ratio. Alternatively, precleaners such as
cyclones could be used upstream of the scrubber to
reduce the paniculate matter concentrations
entering the scrubber.
Venturi scrubber applications generally include a
variable throat system (enabling control of pressure
drop) to enable a constant efficiency to be maintained
at varying inlet conditions. For example, pressure
drops .across venturi throats generally range from 6 to
30 in. HsO in boiler applications. Gas velocities through
the venturi throat may range from 61 to 600 ft/s,
while liquid-to-gas ratios vary from 8 to 15 qal/
1000 ft3 (8).
Design Basis and Costs
The design basis for costs presented in this summary
includes the equipment items shown in Figure 4-14
and the design parameters of Table 4-8. Three
scrubber pressure drops are assumed in order, to
reflect differences in removal efficiency. The overall
collection efficiency for a scrubber system will vary
for specific particle sizes and properties.
Figures 4-16 and 4-17 present total capital
investment and net annual operating expenses.
Table 4- 8. Venturi Wet Scrubber Design Parameters
Parameters Design basis Tvoical ranae"
Gas flow rate, acfm
Inlet paniculate matter
concentration, gr/acf
Pressure drop, in.
Operating pressure
Liquid-to-gas ratio.
gpm/acfm
Materials of construction
Plate thickness, in.
Treatment and disposal
Slurry concentration
to clarifier, % solids
I.OOOto 100,000
2
10.20, and 40
Atmospheric
20
Carbon steel
316 Stainless steel
1/8 to 5/1 6
Clarification.
solids hauling to
landfillc
15
1 ,000 to 200,000
Site specific
6 to 80"
1 atmosphere and
above
10-20
Carbon steel
Fiberglass liners
Stainless steel
Depends on scrubber
size and pressure drop
Site-specific
Site-specific
B200,000 acfm was largest scrubber capacity found in References 8,10, and
14.
"Reference 20, p. 642.
cDesign details for wastewater unit processes are available in Reference21.
Figure 4-16. Venturi wet scrubber system for paniculate
collection - Total capital investment (March,
1980 dollars).
Costs based on carbon steel scrubber with clarifier
for wastewater treatment and solids removal.
For stainless steel scrubber increase costs by about 134%.
A wastewater treatment system with vacuum filtration
increases costs about 30% for a carbon steel scrubber
system.
Costs between 1000 and 10,000 acfm are by graphical
extrapolation.
INVESTMENT
dollars
O
PAL CAPITAL
millions of
p
O
.01
1.
I II HIT
-
I_
-
E X
X
— ' '1 II I I
I 1 r-pTTT
x
X
1 — r i |Mi'.
~
E
-
-
0 10 100 10G
GAS FLOW RATE, thousand acfm
1 10 100
' i I
GENERATING CAPACITY, MWe
10 100 1000
I i
FIRING RATE, 106 Btu/hr
60
-------
Figure 4-17. Venturi wet scrubber system for participate
collection - Net annual operating expenses
(March, 1980 dollars).
Costs based on a carbon steel scrubber with clarifier
for wastewater treatment and solids removal.
For stainless steel scrubber increase costs by about 24%.
A wastewater treatment system with vacuum filtration
increases costs about 18%.
Costs between 1000 and 10,000 are by graphical
extrapolation.
Figure 4-18. Venturi wet scrubber system lor .
collection - Unit annualized cost (March, 1980
dollars).
Costs based on carbon steel scrubber with clarifier for
wastewater treatment and solids removal.
For stainless steel scrubber increase costs by about 52%.
system.
Costs between 1000 and 10,000 acfm are by graphical
extrapolation.
Pressure
Drop
(in. H2O)
10
20
40
CO
111
en
u C
CL- O
LU-D
O_ „_
O o
_j to
<§
Energy
medium
high
Collection
Efficiency
(2um part.)
%
95
99
99.9
Pressure
Drop
(in. H2O)
Energy
Collection
Efficiency
{2urn part.)
1.0
10 100 1000
GAS FLOW, thousand acfm
10 tOO
GENERATING CAPACITY, MWe
10 100 1000
I „—L_ 1
FIRING RATE, 106 Btu/hr
respectively, for wet scrubber systems including
costs for wastewater treatment and solids disposal
Figure 4-18 presents wet scrubber system unit
annualized costs.
A number of possible configurations can' t« used for
wastewater treatment depending on solids settling
characteristics and volume of wastewater treated.
In some scrubber systems a simple settling tank
(sometimes integral with the phys.cal structure of the
scrubber) is sufficient. Solids settle eas.ly and are
removed from the bottom of the vessel as a sludge
which is hauled "as is" to disposal. Clarrf.ed water
from the tank is recycled to the scrubber. Some
'1.0
10 100
GAS FLOW, thousand acfm
1000
GENERATING CAPACITY, MWe
FIRING RATE, 10^ Btu/hr
fractional discharge of the total scrubber water flow
will be required, however, due to a gradual buildup of
dissolved solids in the scrubbing solution. This may or
may not require discharge treatment depending on
the effluent regulations that apply to the specific site.
Other scrubber systems might employ a separate
clarifier-thickenerwith rotating internals to enhance
solids settling and scour sludge solids-from the vessel
bottom into the vessel sludge, discharge port The
clarification thickening process might employ a
chemical additive system. Certain polymers can be
used to enhance solids settling. Thickened sludge
would then be pumped to storage for subsequent
61
-------
hauling to landfill. Or, the sludge might first be
uZT, Htered }°treduce the water comLmX to
wet scrUhShPp°Sal- 'V5 C'ear that the total costal Protection Agency Appendix
ApC°mpl'at;on ^ Air Pollutant Emission Factors,
Q* ,1 « £ce °f Air QualitV Panning and
Standards, Research Triangle Park, NC. February
lyoO. p. A-2.
3. U.S. Department of Commerce, Bureau of the
Census. Current Industrial Reports, Pollution
^Oofla1??1 °OStS and Expenditures, 1978, MA-
4. Sittig, M. Particulates and Fine Dust Removal
Nnvl!SeA a£d Eciu'Pmer>t. Park Ridge, Nd!
NOYES Data Corporation, 1977 p 10
5. Buomcore Anthony J. Air Pollution Control
Chemical Engineering 57(13) p 83
6. Theodore, L, and A.J. Buonicore. Industrial Air
Pollution Control Equipment for Particulates
CRC Press: Cleveland, OH, 1976
7. Webber, D. (Joy/Western Precipitation Division)
lelephone communication with P.J Murin
(Radian Corporation). September 11 1980
rnetenl'< cB,' (GAAD' Inc-> CaPital and Operating
cS!ts °frtSelected Air Pollution Control Systems
EPA-450/5-80-002, U.S. Environmental ProteS
tion Agency, December 1978
9. Tighe, S.C. Mechanical Collectors for Particulate
Control, Stoker Coal-Fired Boilers (Radian
Corporation Internal Technical Note). Octobers
1 "80. '
10. PEDCo Environmental, Inc. CapitalandOperating
Costs of Particulate Controls on Coal- and Oil-
Fired Industrial Boilers. EPA-450/5-80-009 U S
Environmental Protection Agency, Research
Triangle Park, NC, August 1980
11. Oglesby S., Jr. and G.B. Nichols. (Southern
Research Institute) A Manual of Electrostatic
-------
Precipitator Technology, Part I — Fundamentals
EPA No. APTD0610, PB 196 380*, National Air
Pollution Control Administration, Cincinnati, OH
August 1 970.
12. Oglesby, S., Jr. and G.B. Nichols. (Southern
Research Institute) A Manual of Electrostatic
Precipitator Technology, Part II — Application
Areas. EPA No. APTD 0611, PB 196 381*,
National Air Pollution Control Administration!
Cincinnati, OH, August 1970.
13. Danielson, John A. {Ed.} Air Pollution Engineering
Manual, 2nd Ed. EPA No. AP-40, PB 225 132*,
Los Angeles County Air Pollution Control District,
Los Angeles, CA. May 1973.
14. Industrial Gas Cleaning Institute. Air Pollution
Control Technology and Costs in Seven Selected
Areas. EPA-450/3-73-010, PB 231 757*, U.S.
Environmental Protection Agency, Research
Triangle Park, North Carolina, December 1973.
15. Loudin, D.J. (Industrial Gas Cleaning Institute,
Inc.) Electrostatic Precipitator Costs for Large
Coat-Fired Steam Generators. EPA-450/3-78-
045, PB 290 169*, U.S. Environmental Protection
Agency, Research Triangle Park, NC, February
1977.
16. Campbell, K.S., et al. (Stearns-Roger Corporation)
Economic Evaluation of Fabric Filtration Versus
Electrostatic Precipitation for Ultrahigh Paniculate
Collection Efficiency. EPRI-FP-775, EPRI RP 834-1,
Electric Power Research Institute, Palo Alto, CA
June 1978.
Billings, C.E. and J. Wilder (GCA Corporation)
Handbook of Fabric Filter Technology, Vol I, Fabric
Filter Systems Study. EPA No. APTD-0690, PB
200 648*, U.S. Department of Health, Education
and Welfare, Washington, DC, December 1970.
18. Evans, R.J. Methods and Costs of Dust Control in
Stone Crushing Operations. IC-8669, U.S.
Bureau of Mines, Pittsburgh, PA, January 1975.
19. Joy Industrial Equipment Company. Western
Precipitation Gas Scrubbers: Type "V" Turbulaire
Variable Venturi Scrubber. Los Angeles, CA, Joy
Manufacturing Company, 1978. 6 pp.
20. Liptak, B.G., (ed.). Environmental Engineer's
Handbook, Air Pollution, Vol. 2. Chilton Book
Company, Radnor, PA, 1974.
Office of Water Program Operations. Innovative
and Alternative Technology Assessment Manual
EPA-430/9-78-009, U.S. Environmental Protec-
tion Agency, Cincinnati, OH, February 1980.
17
21
"Available for purchase from the National Technical Information Service
5285 Port Royal Road, Springfield, VA 22161.
63
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Section 5
Flue Gas Desulfurizat/on
Sulfur oxide (SO*) emissions (primarily sulfur dioxide,
SOa) arise from fuel combustion and some industrial
processes. Nationwide emissions of SOX were about
30 million tons in 1978(1).
Sources of SOs emissions are regulated by both
federal and state governments. Federal new source
performance standards are now in effect for new
fossiMuel-fired electric power plants. Existing
emission sources are covered by state implementation
plans mandated under the Clean Air Act.
Flue gas desulfurization (FGD) scrubbing systems are
used to absorb SO2 gas from combustion gases to
meet emission regulations. This section presents a
summary of total capital investment, net annual
operating expenses, and unit annualized costs for
FGD systems of the type applied to utility boiler and
industrial boiler stack gases. These systems can also
be used to reduce emissions from other industrial
processes such as smelter operations and process
furnaces.
Two general categories of FGD systems are wet
scrubbing and spray drying systems. The features of
these two categories are discussed separately in the
following pages.
5.1 Wet FGD Scrubbing Processes
The wet FGD processes presented in this report have
been selected because they are the most extensively
used processes and are expected to continue to be
used for future installations.
Wet FGD processes considered here include:
• Lime/limestone.
• Non-regenerable sodium alkali scrubbing (throw-
away).
• Dual alkali.
• Magnesium oxide.
• Wellman-Lord.
The first three are non-regenerable processes. They
produce a major waste stream that requires disposal.
The lime/limestone and dual alkali systems produce
a solid waste stream; the non-regenerable sodium
alkali scrubbing system produces a liquid waste
stream.
The magnesium oxide and Wellman-Lord systems
are regenerate processes which produce a saleable
product instead of a major waste stream. Both
processes yield a concentrated S02Stream which can
be used for liquefied SOz, sulfuric acid, or elemental
sulfur production.
Costs for utility boiler applications are presented for the
lime/limestone, dual alkali, magnesium oxide, and
Wellman-Lord processes. Costs for non-regenerable
sodium alkali scrubbing applied to utility boilers are
not included as this process is used primarily on
smaller industrial boilers. Costs for FGD systems on
industrial boilers are presented for the limestone,
dual alkali, Wetlman-Lord, and non-regenerable
sodium alkali scrubbing processes.
A brief process description is included for each of
these wet FGD processes in Section 5.1.1. Section
5.1.2 discusses the design bases and costs derived
from the major cost references used for this
summary. The cost curves presented show total capital
investment, net annual operating expenses, and unit
annualized costs. Section 5.1.3 provides a discussion
of some of the variables which have a major impact on
costs.
5.1.1 Wet FGD Process Descriptions
This section contains a brief process description for
each of the FGD systems contained in this summary.
Stack gas reheat (SGR) is shown in each FGD system.
SGR has been used following wet FGD processes to
protect downstream equipment against corrosion
and to achieve better plume dispersion.
Lime/Limestone Scrubbing Process
In the lime/limestone process, a slurry containing
calcium hydroxide or calcium carbonate removes SO2
from flue gas in a wet scrubber. Both of these
processes are non-regenerable processes and
produce a large volume of solid waste for disposal.
The lime and limestone systems are considered
together here because of their similarity. A block
diagram showing the major processing areas in
lime/limestone scrubbing is given in Figure 5-1.
Participate matter is normally removed upstream of
the FGD system. After paniculate matter removal, the
flue gas enters the scrubber where S02 is absorbed
by contact with a slurry of lime or limestone in water.
The S02 chemically reacts with the lime or limestone
to form calcium sulfite and calcium sulfate.
64
-------
Figure 5-1. Lime/limestone scrubbing process lor flue gas desulfurization.
Lime/
Limestone
Prepara-
tion
Gas
Streams
Liquid, Slurry
or Solid
Streams
Calcium sulfite and sulfate crystals are only slightly
soluble in water and precipitate from solution. The
slurry passes through the scrubber into a hold tank.
The hold tank is designed to allow enough time for
solids precipitation to proceed. Fresh lime or
limestone is also added to this tank. Most of the slurry
is recirculated to the scrubber. The remainder is
continually removed from the hold tank for solid/liquid
separation by ponding or clarification/vacuum
filtration processes. In ponding, the-pond serves as
the final solids disposal method as well as liquid
clarifier. Solids from filtration are usually disposed of
in a landfill. In either case, the clarified liquid is
returned to the scrubber system for reuse.
The lime/limestone process is by far the most
extensively used FGD system for utility boilers,
representing more than 80 percent of FGD units in
operation or under construction (2). By contrast, less
than 5 percent of the industrial boiler FGD
installations are lime/limestone (3). The non-regener-
able sodium alkali scrubbing process, described in the
next section, has been preferred in-small boiler
applications partly because of its simplicity, low
maintenance requirements, and low total capital
investment.
Non-regenerable Sodium Alkali Scrubbing
(Throwaway) Process
In sodium alkali scrubbing systems, a scrubbing
solution of sodium hydroxide, sodium carbonate, or
sodium bicarbonate absorbs SO2 from flue gas. A
block diagram showing the various sodium scrubbing
process modules is presented in Figure 5-2.
The SO2 chemically reacts to form sodium sulfite and
sodium bisulfite which remain dissolved in solution.
Part of the sulfite in solution reacts with oxygen from
the flue gas to form sodium sulfate. The sodium
sulfite and sulfate salts are removed from the system
in solution as a liquid waste. Sodium carbonate
(NazCOs) or sodium hydroxide (NaOH) are generally
selected as the makeup sodium alkali added to the
recirculating scrubber solution to compensate for the
quantity that reacts with SO2.
Sodium alkali scrubbing differs from limestone and
dual alkali FGD systems in that ho solid waste product
is formed. However, larger quantities of liquid waste
containing sodium sulfite, sodium bisulfite, and
sodium sulfate must be disposed of. Disposal
practices for this waste stream include wastewater
treatment, holding ponds for evaporation, and deep-
well injection.
The non-regenerable sodium alkali scrubbing process
is the simplest FGD process described in this report
from the standpoint of operation and maintenance.
Even so, only four utility systems are operational (4).
This is largely due to the liquid waste disposal
problem and the high cost of the sodium chemicals
required for scrubbing. However, for industrial
boilers, non-regenerable sodium alkali scrubbing has
been the preferred process to date with over 100
65
-------
operational systems (3). Many of these systems are
very small (treating flue gas from a boiler with a firing
rate of less than 100 x 106 Btu/hr). In these systems,
a premium has been placed on simplicity, low capital
cost, and reliability during operation. The non-
regenerable sodium alkali scrubbing process meets
these requirements and has found extensive use in
spite of high chemical costs. However, future
application of this process is limited in many areas of
the country due to the high cost of treating the liquid
waste for final disposal.
Dual Alkali Scrubbing Process
The dual alkali process encompasses some features
of both the non-regenerable sodium alkali scrubbing
and lime FGD processes. The scrubbing liquid is a
solution of soluble sodium-based alkali containing
sodium carbonate, sodium bicarbonate, sodium
sulfite, and sodium hydroxide. Calcium-based solids,
similar to those formed in lime/limestone systems,
are produced by addition of lime to a stream of spent
scrubbing liquor. A block diagram showing the
various dual alkali process modules is presented in
Figure 5-3.
After removal of paniculate matter, the flue gas
enters the scrubber where SO2 is absorbed. The S02
reacts chemically with sodium alkali to form sodium
sulfite and sodium bisulfite. Some of the sodium
sulfite reacts in solution with oxygen (02) from the
flue gas to form sodium sulfate.
A side stream of scrubbing solution is reacted with
slaked lime to form calcium sulfite and calcium
sulfate which precipitate from solution. This process
step also results in regeneration of the sodium-based
alkali for recycle to the scrubber. The regenerated
solution contains sodium sulfite and sodium
hydroxide.
The side stream slurry, which contains calcium
sulfite and sulfate solids, is sent to a thickener where
solids are concentrated by sedimentation. This forms
a sludge of solids and water which is further
thickened in a vacuum filter and then washed to
recover sodium salts. The solids are then disposed of
by either ponding or landfill. Clarified solution from
these steps is returned to the scrubber.
Dual alkali systems can be classified as either dilute
mode or concentrated mode processes, depending on
the concentration of alkali in the scrubbing liquid. The
choice between these two operations is determined
by how much sulfite reacts with oxygen as discussed
above. The quantity of sulfite that reacts depends on
site-specific factors such as the relative concentrations
of SC*2 and O2 in the flue gas. The sodium sulfate
formed must be removed from the system to maintain
SO2 removal capability, and precipitation of sodium
sulfate in the clear liquid circulation loop. The two
operations differ in the manner in which sulfate is
removed from the system.
The dilute mode system is applicable in systems
where high oxidation rates are expected. Firing of low
sulfur coal produces flue gas characteristics for
which the dilute mode is better suited. Concentrated
mode systems are applicable where high sulfur coal
is encountered. Most existing dual alkali systems on
both utility boilers and industrial boilers use the
concentrated mode (3).
Magnesium Oxide Scrubbing Process
The magnesium oxide or magnesia slurry absorption
process is a regenerable process which uses
Figure 5-2. Sodium alkali scrubbing (throwaway) process for flue gas desulfurization.
Sodium
Alkali
Handling
and
Preparation
Liquid, Slurry,
or Sol id
Streams
66
-------
Figure 5-3. Dual alkali scrubbing process for flue gas desulf urization.
Stack
Gas
Reheat
SO2
Absorption
Particulate
Removal
Flue Gas to
Atmosphere
Regenerated Scrubbing Liquor
Soda Asn
Handling
Preparation
Solid/
Liquid
Separation
Liquid, Slurry, |
or Solid |
Streams j
Lime
Handling
and
Preparation
Solids
Disposal
Reaction
Vessel
System Boundary
magnesium hydroxide to absorb S02 in a wet
scrubber. A block diagram showing the major
processing areas for the magnesium oxide process is
presented in Figure 5-4.
After particulate removal, the flue gas may be
pretreated in a pre-scrubber for chloride removal to
prevent excess concentrations of chloride in the
scrubbing liquid. Then the flue gas is contactedI with
magnesia slurry in a scrubber to remove S02. The bU2
reacts with the magnesium hydroxide to form
magnesium sulfite and magnesium bisulfite. Some
of the sulfite formed in the above reactions reacts
with oxygen from flue gas to form magnesium
sulfate.
Spent slurry from the scrubber is sent to a hold tank
designed to provide sufficient holding time for the
solids to precipitate. The sulfite and sulfate solids
precipitate as hydrated crystals.
The hold-tank effluent is split into two streams. The
first stream of relatively clear liquid is combined with
fresh magnesium oxide and recycled slurry. This
stream is then recycled to the scrubber.
The second stream of liquid and settled solids is sent
to a thickener for solids concentrations. After further
solids concentration in a centrifuge, the magnesium
sulfite and magnesium sulfate hydrated crystals are
regenerated to produce fresh ma9nesium
regeneration step takes place in two stages.
water is driven off in an oil-fired rotary k. n. Then the
dried magnesium sulfite and magnesium sulfate
c ystals a?e calcined. During calcining, magnesium
Stfite and magnesium sulfate.are converted^to
magnesium oxide with the evolut.on of S02 jas. The
off-gas from the calciner contains from 8 to 1O
percent SOa and is used in a downstream recovery
process such as sulfuric acid production (3).
The magnesium oxide process has been shown to be
feasible on a full-scale utility boiler system. Three
units all retrofits in the 95 to 150 MWe size range,
have demonstrated greater than 90 percent SOz
removal on both coal-fired and oil-fired sys ems. At
present, however, only one of these unrtssm
operation (4). There are no applications of the
magnesium oxide system on industrial bo.lers in the
U.S. (3).
Wellman-Lord Scrubbing Process
The Wellman-Lord scrubbing system is a regeneraWe
process that uses a sodium sulfite solutioni to absorb
S02 It produces a concentrated stream of S02 that
can be processed into elemental sulfur, sulfur.c acid,
oHiquid'SO* A block diagram showing the major
67
-------
Figure 5-4. Magnesium oxide scrubbing process for flue gas desulfurization.
Fresh &
Makeup
MgO
Handling &
Preparation
Gas
Streams
Liquid, Slurry
or Solid
Streams
processing areas required for Wellman-Lord scrub-
bing is presented in Figure 5-5.
In addition to the usual removal of paniculate matter
the flue gas is also pretreated in a venturi scrubber for
chlonde removal to prevent excessive chloride
concentrations in the scrubbing liquid.
Humidified gas from the prescrubber enters the
absorption tower where it is contacted with the
scrubbing hquor. Sodium sulfite reacts in solution
with oxygen from the air to form sodium sulfate The
sulfate must be removed from solution in order for the
scrubbmg liquid to maintain its ability to absorb S02
A portion of the spent scrubbing liquid is sent to a
treatment step which may employ either a heated
sulfate crystalhzer or a refrigerated chiller-crystallizer
Both produce a slurry of sodium sulfate solid crystals
which is centrifuged. The resulting cake of solids is
dried with steam, and disposed of as solid waste.
The remainder of the spent scrubbing liquid is
regenerated by converting sodium bisulfate to
sodium sulfite. This is accomplished by heating the
l'qu,d ,n a set of double-effect forced-circulation
evaporators. Sodium sulfite crystals formed during
this regeneration step are dissolved in water and
recycled to the SO2 absorber. The concentrated SO2
« Zn«rT!?V-be U,S6d for Production of elemental
sulfur, sulfunc acid, or liquid SO2.
68
nct n f 3re Seven weHman-Lord systems
installed on utility boilers in the U.S. Three of these
systems produce elemental sulfur as a by-product
while the other four produce sulfuric acid (4) The
predominant use of the Wellman-Lord system in the
manufacturing industrial sector is for removal of S02
from Glaus plant and sulfuric acid planttailgas These
systems desulfurize streams having SO2 concentra-
hat £Ti? T 2J°° f° 1 a000 ppm' hj9her than
that normally found in boiler flue gas. The hiah
alkalmity of the Wellman-Lord scrubbing so.uton
achieves good removal ofS02 from these concentrated
gas streams. Currently there are no Wellman-Lord
systems installed on industrial coal-fired boilers (3).
5.7.2 Design Basis and Costs
Costs of wet FGD systems for utility boilers and
industrial boilers are presented in this section. Cost
data for utility boiler applications were available from
two primary sources: estimates developed by the
Tennessee Valley Authority (2, 5), and estimates by
PEDCo Environmental, Inc. (6). Costs adapted from
the latter source only have been used as the bases of
^ort!;UrreS,Pi;eSented in this rePQrt' as explained
shortly. Costs for industrial boiler applications were
obtained from estimates developed by Radian
Corporation (3). These sources were selected in part
because each contains cost estimates for most of the
-------
Figure 5-5. Wellman-Lord scrubbing process for flue gas desulfurization.
Flue
Gas
Desulfurized
From
Boiler
Regenerated Scrubbing Liquor
1 '
1
I Na2SO4
J 4 Solids
Sulfate
Removal
Gas
Streams
Liquid, Slurry
or Solid
Streams
L
System Boundary.
types of FGD systems evaluated in this study and
because the costs were well documented. In addition,
each of these references is relatively recentandeach
contains information on the effect of important
variables on capital investment and annual operating
expenses.
The design bases used in these references differ in
some important respects. Some of the more
significant factors are listed in Table 5-1. The design
bases (and resultant costs) published by TVA' reflect
early FGD design concepts that may not apply to
future installations. They do however, provide a
baseline for illustrating relative cost effects due to
differences in design basis as discussed in Section
5.1.3.
Cost for wet FGD systems are presented in Figures 5-
6 through 5-11 for utility and industrial boilers.
Capital costs are expressed as total capital investment.
The curves reflect the cost of a new FGD system
treating flue gas from a boiler burning 3.5 percent
sulfur coal. Included in the total capital investment
are costs for the purchase and installation of all
equipment in each of the process areas within the
system boundary defined in Figures 5-1 through 5-5
and described in Table 5-1. Annual operating costs
are expressed as net annual operating expenses and
Table 5-1. Comparison of Design Bases for Major Cost References
TVA (2, 5}
Utility boiler application
PEDCo (6)
Utility boiler application
Radian (3)
Industrial boiler application
• Cost estimates are for new units.
• Size range from 200 to 1000 MWe
{1840x 106to8700x 106Btu/hr).
• Coal contains 3.5 percent sulfur and has
a heating value of 10,500 Btu/lb.
• System designed for allowable emissions
of 1.2 lb/10 Btu (78.5 percent removal
for a 3.5 percent sulfur coal).
(Continued)
Design factors common to all FGD systems
• Cost estimates are for new units.
• Size range from 100 to 1000 MWe
(950 x 106 to 8700 x 106 Btu/hr).
• Coal contains 3.5 percent sulfur and has
a heating value of 12,000 Btu/lb.
• System designed for 90 percent removal
of maximum anticipated 3-hour average
coal sulfur content.
Cost estimates are for new units.
Size range from 30 x 106 to 400 x 106
Btu/hr.
Coal contains 3.5 percent sulfur and
has a heating value of 11,800 Btu/lb.
System designed for 90 percent
removal.
69
-------
Table 5-1 (Continued)
TVA (2, 5)
Utility boiler application
PEDCo (6)
Utility boiler application
Radian (3)
Industrial boiler application
1 No process redundancy except for spare
pumps.
Stack gas reheat to 175°F.
Operating capacity factor is 0.80.
Heat rate, Btu/kWhe-9200 at 200 MWe,
9000 at 500 MWe, and 8700 at 1000 MWe.
ESP and associated induced draft fans
not included in cost. Cost of forced
draft fan (relative to FGD unit)
included for each scrubber train.
Costs include all ductwork associated
with FGD unit.
No gas bypass provisions.
30-year life.
Midwest location.
• One spare scrubber, excess in-process
storage capacity, and spare pumps.
• Stack gas reheat to 175°F.
• Operating capacity factor is 0.65.
• Heat rate, Btu/kWhe - 9500 at 100 MWe,
9200 at 200 MWe, 9000 at 500 MWe,
and 8700 at 1000 MWe.
• Particulate matter removal costs not
included.
Costs include ad ductwork associated
with FGD unit.
Complete gas bypass provisions.
35-year life.
Midwest location.
No process redundancy except for
spare pumps.
No stack gas reheat.
Operating capacity factor is 0.60.
Not applicable.
Particulate matter removal costs not
included. Cost of fan for FGD system is
included.
Costs include all ductwork associated
with FGD unit.
No gas bypass provisions.
15-year life.
Midwest location.
Scrubbers are turbulent contact absorber
(TCA) variety.
Solids disposal method is ponding of
hold tank slurry. Capital costs include
cost of pond construction and 1-mile
pipeline for transport of slurry to pond.
Design factors specific to lime/limestone systems
Scrubbers are turbulent contact absorber
(TCA) variety.
Solids disposal method is ponding of
thickened slurry after stabilization
with lime and fly ash. Capital costs
include clarifiers and on-site pond
construction.
Scrubber is turbulent contact absorber
(TCA) variety.
Solids disposal method is off-site land-
fill. Disposal cost is S15.00/ton at 50
percent solids. Capital costs include
costs for clarifiers and filters but not
for landfill site preparation.
Design factors specific to sodium alkali scrubbing (throwawayj systems
(Costs for sodium scrubbing systems
were not developed in this reference.)
Scrubbers are perforated plate type.
Solids disposal method is reslurry and
ponding of waste solids. Capital costs
include thickener, filter, reslurry
equipment, 1-mile pipeline for slurry
transport, and pond construction.
Concentrated mode operation with
sodium absorbent and lime regenerant.
(Costs for sodium scrubbing systems were
not developed in this reference.)
Design factors specific to dual alkali systems
• Scrubbers are tray type.
• On-site ponding.
Not specified-assumed to be the same
as TVA.
Scrubber is tray tower type.
Costs for waste liquor treatment are
not included in total capital invest-
ment or total annual operating
expenses.
Sodium alkali is soda ash
Scrubbers are tray type.
Solids disposal method is off-site land-
fill. Disposal cost is S15.00/ton at 50
percent solids. Capital cost include the
costs of a clarifier and filter but not the
cost for landfill site preparation.
Concentrated mode operation with
sodium absorbent and lime regenerant.
Scrubber is spray grid column type.
By-product credit for H2S04 production.
Capital and operating costs included
for acid plant.
Venturi prescrubber for chloride removal
included in costs.
Design factors specific to Mag-Ox systems
• Scrubber is turbulent contact absorber
(TCA) type.
• By-product credit for H2SO4 production.
Capital and operating costs included for
acid plant.
• Information on presence of a prescrubber
not specified in reference.
(Costs for Mag-Ox systems were not
developed in this reference.)
(Costs for Wellman-Lord systems were not
developed in this reference.)
Design factors specific to Wellman-Lord systems
» Scrubber is tray type.
I By-product credit for H2SO4 production.
Capital and operating costs included
for acid plant.
I Information on the presence of a pre-
scrubber not specified in reference.
• Scrubber is tray type.
By-product credit for sulfur production.
Capital and operating costs included
for sulfur production facilities.
Venturi prescrubber for chloride remov-
al included in costs.
70
-------
Figure 5-6. Flue gas desulfurization systems for utility
boilers • Total capital investment (March,
1980 dollars).
Costs are for limestone systems. For other technologies
multiply costs by:
Lime
Dual Alkali
Mag-Ox
Wellman-L<
200
180
TOTAL CAPITAL INVESTMENT
millions of dollars
— L -i _l _l
N> -P- CT> 00 O W *>. O)
_O OOO OOOOO
0,9
1.0
1.1
3rd 1.0
-
r
r x
~'l Illl 1 I 1
A
y
\
,/
r
'" =
/?
-^
~
200 400 600 800 1000
GENERATING CAPACITY, MWe
0 1600 3200 4800 6400
8000
FIRING RATE, 10** Btu/hr
0.64 1.28 1.92 2.56 3.20
—I 1 I I .1
GAS FLOW RATE, 106 acfm
Figure 5-7. Flue gas desulfurization systems for utility
boilers • Net annual operating expenses
(March, 1980 dollars).
Costs are for limestone systems. For other technologies
multiply costs by:
Lime
Dual Alkali
Mag-Ox
Wei I man-Lord
CO
UJ
CO
z
*
UJ
££
ll
G
l-
UJ
z
50
40
30
^ 20
o
10
grin
0.9
1.0
1.2
1.0
TTTr
n i rr rrrq
200 400 600 800
GENERATING CAPACITY, MWe
1600
I
3200 4800
6400
1000
8000
FIRING RATE, 106 Btu/hr
0.64
1.28
1.92
2.56
I
3.20
GAS FLOW RATE, 106 acfm
include operating and maintenance costs as well as
some capital-investment-related charges. Deprecia-
tion is not included. Unit annualized costs are given
as cents/kWh and were obtained by calculating
annualized cost and dividing by actual annual amount
of electricity generated in kwh. Depreciation is
included. (See Appendix A for a discussion of
annualized cost and unit annualized cost.)
Total capital investment net annual operating
expenses, and unit annualized cost are presented as
a function of FGD system capacity. On the graphs for
large boilers, the capital cost scale includes the
electrical generating capacity (for utility boiler), the
boiler firing rate (in 106 Btu/hr), and gas flow rate (in
103 acfm). Cost for FGD systems on industrial boilers
are presented as a function of boiler firing rate (10e
Btu/hr) and gas flow rate (103 acfm).
5.1.3 Major Variables Affecting Costs
The discussion below of some of these variables calls
attention to factors which must be considered in
evaluating and comparing estimated and reported
costs for FGD systems. Utility boiler and industrial
boiler FGD system applications are discussed
separately in Sections 5.1.4 and 5.1.5, respectively.
5.1.4 Utility Boiler FGD Systems
A review of costs published in the two key sources
used in this report for utility FGD systems applied to
large boilers showed considerable differences for
both total capital investment and net annual
operating expenses {2, 5, 6). An analysis of the data
reveals that differences are due primarily to design
bases rather than errors or inconsistencies in the
estimates. Specific differences which illustrate how
design criteria have a major impact on costs are
described below:
71
-------
Figure 5-8. Hue gas desulturization systems for utility
boilers • Unit annualized cost (March, 1960
dollars).
Costs are for limestone systems. For other technologies
multiply costs by:
Lime
Dual Alkali
Mag-Ox
Well man-Lord
0.9
1.0
1.2
1.0
200 400 600 800
GENERATING CAPACITY, MWe
1600
3200
i
4800
_J
6400
t
1000
8000
0.64
j
FIRING RATE, 1Q6 Btu/hr
1,92
1.28
i
2.56
t
3.20
I
Figure 5-9- Flue gas desulfurization systems for industrial
boilers • Total capital investment (March, 1980
dollars).
Costs are for dual alkali systems. For other technologies
multiply costs by:
Limestone 1.0
Sodium Alkali 0.7
Wellman-Lord 2.2
2
LU
—
>
10.0
8.0
tL o 4.0
< =
<
p 2.0
JIIIIM n
~
'-
~
".,..1....
i n IN 1 1 1
^^
<^
1 1 1 ili 11 1
Ml 1 1 1 II
^
n n| 1 1 n
^
• i. . 1 1 1 11
II II MIL
-E
-=
-:
tin i nr
100 200 300 400 500
FIRING RATE, 1Q6 Btu/hr
41 82 124 165 206
GAS FLOW RATE, thousand acfm
GAS FLOW RATE, 1Q6 acfm
The TVA estimates reflect 78.5 percent sulfur
removal, while the PEDCo estimates are based on
90 percent sulfur removal, for coal containing an
average of 3.5 percent sulfur. In addition, the
PEDCo scrubber design basis accounts for
variability from the average in the actual coal
sulfur content. The PEDCo scrubber system is
designed to achieve 90 percent SO2 removal from
coal which may have an average 3-hour sulfur
content as high as 4.61 percent, although the
nominal average is 3.5 percent. The TVA estimates
do not take into account coal sulfur variability.*
*As stated in Section 5-1.2, the published TVA data reflected early design con-
cepts. At the time this report was prepared, new TVA estimates were
available only for lime/limestone systems. Costs for other technologies on
a consistent TVA basis were not available. The newer TVA estimates for
lime/limestone systems are relatively close to the PEOCo estimates.
Reported costs far actual systems installed to date are lower that the
estimated costs in this report, and lie between the TVA estimates based on
early design concepts and the PEDCo based estimates.
• The TVA design basis does not include redu ndancy
in any process equipment except pumps. Cost
increases are substantial when, for example,
redundant scrubber modules are employed. The
PEDCo cost estimates include a spare scrubbing
module and associated equipment, spare pumps,
and excess in-process storage capacity.
• Provisions for gas bypass are included in the
PEDCo estimates, but not in the TVA estimates.
The effects of the above factors on total capital
investment are illustrated in Tables 5-2 and 5-3.
Table 5-2 shows the effects of different design bases
on the PEDCo-derived total capital investment
estimates for several FGD systems. Although the
percent reductions in total capital investment given
in Table 5-2 are not directly additive, the results are
an indication of the size of changes in the total capital
investment that can occur by specifying different
design bases.
72
-------
Figure 5-10. Flue gas desulfurization systems for industrial
boilers • Net annual operating expenses
(March, 1980 dollars).
Costs are for dual alkali systems. For other technologies
multiply costs by:
Limestone 1.0
Sodium Alkali 0.9
Wellman-Lord 1.2
NET ANNUAL OPERATING EXPENSES
millions of dollars per year
o o r" ->• r*
ji. 00 TO O) C
0
j i . . 1. 1 i .
:
=>...!...,
/
/
..,,!.,..
/
'
... .!....
""I""
/
,,,,],,,,
-_
~
-=
-^
-
,,,,!,,,,=
) 100 200 300 400 5C
FIRING RATE, 106 Btu/hr
41
82
i
124
i
165
206
__j
GAS FLOW RATE, thousand acfm
Figure 5-11. Flue gas desulfurization systems for industrial
boilers - Unit annualized cost (March, 1980
dollars).
Costs are for dual alkali systems. For other technologies
multiply costs by:
Limestone 1.0
Sodium Alkali 0.9
Wellman-Lord 1.5
500
400
O)
O =
Om
So 300
"Z. a.
200
100
100 200 300 400 500
FIRING RATE, 106 Btu/hr
41
82 124 165 206
_! 1 | |
GAS FLOW RATE, thousand acfm
Table 5-3 shows the effects of a modified design basis
on the TVA total capital investment estimate for the
limestone slurry process. The important result here is
the nearly doubled total capital investment figure
which results from the modified design basis.
The factors described above, together with other less
significant factors in the design bases, account for the
difference between the TVA and PEDCo derived total
capital investment estimates. At the time this report
was initially prepared, TVA was in the process of
updating its design basis to include redundancy.
Numerous other design basis changes were also be-
ing incorporated that would make theTVA and PEDCo
design bases more similar. The resulting total capital
investment available for a lime/limestone system for
the new TVA basis is nearly the same as that given by
PEDCo (7).
Actual reported total capital investment for new
electric utility FGD systems constructed within the
last 10 years falls roughly midway between the TVA
(old basis) and PEDCo cost estimates (4). However,
when the reported costs are adjusted to include costs
for reheat and scrubber redundancy, if not already
included in the process configuration, the reported
costs are in closer agreement with the PEDCo and the
TVA (new basis) estimates. As a result of the 1979
New Source Performance Standards, future utility
installations will probably be constructed with
redundancy for reliability. For this reason the PEDCo
costs were used for the cost curves in this report. A
complete set of new TVA costs was not available
when this report was being prepared.
Large differences also exist for net annual operating
expenses derived from the TVA (2, 5) and PEDCo (6)
estimates. Again PEDCo figures result in higher
costs. This fact is somewhat misleading, because
about 75 percent of these differences are directly
related to the higher total capital investment figure
used in the PEDCo estimates. The remaining
differences are the result of a variety of factors,
including sludge handling and fixation chemical
costs and higher utility consumption rates.
Differences between the TVA and PEDCo design
bases which affect costs have been described above.
There are, however, several other factors which can
have a significant effect on costs, including:
73
-------
Table 5-2. Effect of Changes in the Design Basis on PEOCo Total Capital Investment Estimates (6)3
Example
Lime
process
Limestone
process
Dual alkali
process
Mag-Ox
process
We 11 man-Lord
process
Base case - New 500 MWe unit $83,770,000
burning 3.5 percent sulfur ($1 67.5/kWe)
coal. 90 percent removal based
on 3-hour average coal sulfur
variability. Five scrubber
trains (including one redundant
module).
Case I - Emissions level of
1.2lbSO2/106Btu
(—80 percent removal)
Case II - 90 percent removal 4.3%
based on 1-year average coal ($160.3/kWe)
sulfur variability
Case III - Elimination of 18.8%
redundant scrubber module ($136.0/kWe)
Base case capital investment
$96,200,000 $98,010,000 $ 104,760,000 $92,960,000
($192.4/kWe) ($196.0/kWe) ($209.5/kWe) ($185.9/kWe)
Percent decrease in total capita/ investment from base case"
10.4% 11.0% 10.2% 10.2% 8.9%
($150.1/kWe) ($171.2/kWe) ($176.0/kWe) ($188.1/kWe) ($169.4/kWe)
N/AC
N/A
N/A
N/A
N/A
N/A
N/A
17.4%
($153.6/kWe)
'March 1980 dollars.
"Example for the lime process - If an emissions level of 1.2 Ib SO2/106 Btu is used as the design basis, the total capital investment would be
$ 150.1/kWe which is 10.4 percent lower than the base case total capital investment of $167.5/kWe.
°N/A - Data not available.
Table 5-3. Effect of Changes in the Design Basis on TVA
Total Capital Investment Estimates (5)a
Percent
Base case - Limestone slurry process, new 500 MWe increase
unit burning 3.5 percent sulfur coal. 80s level over
of 1.2 Ib. No scrubber redundancy $/kWe base case
Base case total capital investment, $/kwe 107.7
Modified case - limestone slurry process. New 500 MWe
unit burning 6 percent sulfur coal. SOs efficiency
of 90 percent. 50 percent redundancy.
Total capital investment increase due to:
Increased raw material handling 20.2 18.8
Larger waste disposal area and pond 51.8 48.1
50 percent redundancy of ball mills, scrubbers,
and other equipment 34.0 31.6
Total increase in total capital investment 106.0 98.5
Modified case total capital investment 213.7
"March 1980 dollars.
• Solid waste disposal method.
• New unit versus retrofit applications.
• Boiler fuel type and sulfur content.
Costs for the lime, limestone, and dual alkali
processes are signficantly affected by the choice of
the solids disposal method. Capital costs for ponding
scrubber slurry are higher than those for landfill
disposal of solid waste. Available data (8) suggest that
use of landfill disposal reduces total capital
investment by up to about 18 percent, depending on
the landfill method. However, net annual operating
expenses are higher for landfill disposal due to solids
handling and disposal costs and raw material costs if
stabilization or chemical fixation is required. The
choice of the most appropriate waste disposal method
for utility boilers is largely dependent on site-specific
factors such as land availability, topography,
groundwater characteristics, and climate. The total
numbers of applications of ponding and landfill
disposal methods are about equal. This analysis
included both operational and planned FGD systems.
Fuel type and sulfur content also affect both capital
investment and annual expenses. Increases in fuel
sulfur content result in more sludge and hence a
larger solids handling system and waste disposal
area for non-regenerable systems. Magnesium oxide
and Wellman-Lord systems require larger regeneration
facilities. Annual expenses also increase because of
higher raw material and utilities consumption and
higher waste disposal costs. Table 5-4 shows the
effect of coal sulfur content on total capital
investment and total net operating expenses (6).
Because of lower scrubber costs, FGD systemson oil-
fired units cost slightly less than those on fired
boilers, there is a smaller volume of gas flow.
5.1.5 Industrial Boiler FGD Systems
The process configuration and costs for industrial
boiler FGD systems differ from those of utility boiler
FGD systems for a variety of reasons. Some of the
more important differences include:
• Waste disposal method.
• Stack gas reheat provision.
• Redundancy.
• Shop-fabricated versus field-erected equipment.
Ponding and landfill waste disposal options are used
in equal numbers in applications for lime, limestone,
and dual alkali processes on utility boiler FGD
systems. Industrial boiler FGD systems, however,
generally use the landfill disposal method. Many
industrial locations do not have sufficient land
available for pond construction. The use of landfill
disposal also requires a lower total capital investment
Stack gas reheat and redundancy in process
equipment, often incorporated in utility applications,
are not extensively used in industrial boiler FGD
systems. The omission of these equipment items
74
-------
Table5-4. Effect of Coal Sulfur Content on Total Capital Investment and Total Annual Operating Expenses for Utility Boiler
Applications (6)a b
Lime Limestone Double alkali Mag-Ox Wellman-Lord
process process process process process
Base case - New 500 MWe unit
burning 3.5 percent sulfur
coal. 90 percent SO£ removal.
Base case total capital nnn
investment^ 87,770,000 96,200,000 98,010,000
Base case net annual
operating expenses, S/yr 23,180,000 24,360,000 28,990,000
Case I - 7.0 percent sulfur coal
Percent increase in total
capital investment 12.7 16.5 12.2
104,760,000 92,960,000
29,750,000 22,720,000
17.9
9.2
Percent increase in net
annual operating expenses
Case II - 0.8 percent sulfur coal
Percent decrease in total
capital investment
Percent decrease in net
annual operating expenses
26.7
14.4
31.9
27.2
14.3
23.7
34.2
N/AC"
N/A
25.8
N/A
N/A
8.6
N/A
NA
process - If coal with a sulfur content of 7 percent is used as the design basis, the total capital investment would
increase by 12.7 percent over the base case total capital investment.
CN/A - data not available
substantially reduces the required total capital
investment. The costs presented in this report for
industrial boiler FGD systems do not include these
items.
An obvious difference between utility boiler and
industrial boiler FGD systems is their relative size. An
important consequence of this size difference is the
manner in which the FGD systems are constructed.
Because of their size, utility systems must be field-
erected, while major components of the smaller
industrial boiler FGD systems can be shop-fabricated
and transported by truck or rail to the site. Total
capital investment is lower for shop-fabricated
equipment than for field-erected equipment.
Total capital investment and net annual operating
expenses for industrial boiler FGD systems are also
affected by the required percent S02 removal and the
fuel sulfur content. The effect of these variables on
capital investment and operating expenses is
summarized in Table 5-5.
There are also differences between coal- and oil-fired
boilers. Coal-fired boilers typically result in a higher
flue gas rate for a given firing rate than oil-fired
boilers. This is due to combustion characteristics of
the different fuels. As a result, the scrubbing section
of an FGD system is more expensive for coal-fired
applications at comparable firing rates.
5.2 Lime Spray Drying Process
Spray drying is a relatively new FGD technology. At
this writing, three industrial systems and one large-
scale (100 MWe) utility demonstration system are
operational. There are another four industrial-size
spray drying systems planned or under construction
(9). No commercial utility lime spray drying systems
are operating. However, 10 utilities have purchased
such systems, and about half of those are scheduled
to start up in the next 2 or 3 years.
In spray drying systems the S02 gas is either ab-
sorbed or adsorbed onto the sprayed materials.
The utility systems will be used on boilers firing low
sulfur coal (1.5 percent sulfur or less) in most cases.
The sulfur content of the coal burned in the industrial
applications ranges from 0.7 to 3.5 percent in the
operating or planned systems to date.
5.2.1 Process Description
In lime spray drying systems, flue gas at air preheater
outlet temperatures (generally between 250 and
350°F) is contacted with a finely atomized lime slurry in
a spray dryer. Figure 5-12 is a block flow diagram of
the spray drying process. The flue gas is adiabatically
humidified to within 20 to 50°F of its saturation
temperature as water evaporates from the slurry. SOg
in the flue gas reacts with the calcium hydroxide in the
slurry to form calcium sulfite, some of which is
oxidized to calcium sulfate by oxygen in the flue gas.
Heat from the flue gas dries the calcium sulfite and
sulfate solids to less than 1 percent residual
moisture. The bulk of these solids, along with the fly
ash in the flue gas, pass through the dryer and are
collected in a downstream fabric filter or electrostatic
precipitator (ESP). In some system designs, a portion
of the solids are collected from the bottom of spray
dryer.
75
-------
Table 5-5.
Effect of Coal Sulfur Content and SOa Removal Efficiency on Total Capital Investment and Total Annual Operating
Expenses for Industrial Boiler Applications (3)a b w§wr«un8
Limestone
process
Sodium throwaway
process
Double alkali
process
We lima n-Lord
Base case - New FGD unit applied to a
200 x 106 Btu/hr boiler burning 3.5
percent sulfur coal. 90 percent
SO2 removal.
Base case total capital
investment, S
Base case net annual
operating expenses, S/hr
Case 1 - 75 percent removal
Percent decrease in total
capital investment
Percent decrease in net
annual operating expenses
Case II - 0.6 percent sulfur coal
Percent decrease in total
capital investment
Percent decrease in net
annual operating expenses
"March 1 980 dollars " "
2,100,000
1,060,000
7.4
10.8
15.3
33.0
1,480,000
1,000,000
2.3
7.7
16.1
41.2
2,230,000
1,050,000
N/AC
N/A
16.1
34.9
4,960,000
1,420,000
N/A
N/A
45.4
41.0
°N/A - Data not available
Figure 5-12. Lime spray drying process for flue gas desulfurization.
Particulate
Matter Collection
(ESP or Fabric Filter)
Gas Streams
Liquid, Slurry, or
Solids Streams
76
-------
The dry waste product from the lime spray drying
process is usually disposed of by landfill. As shown in
Figure 5-12, a portion of the product solids/fly ash
mixture can be recycled back to the dryer. This
scheme reduces fresh lime requirements by taking
advantage of any unreacted reagent or availability of
fly ash alkalinity in the solids.
The reader should note that, in contrast to the wet FGD
system boundaries presented earlier, the spray
drying system Includes a fabric filter for paniculate
control * The paniculate matter collection system is
an inherent component of the dry FGD system, and it
has been observed to contribute to adsorption of
additional S02. The reader should take this fact into
account when comparing the costs for spray drying
with those presented earlier for wet FGD systems
which do not include the costs of paniculate matter
control.
Another less significant difference inthescopeof the
wet FGD systems and lime spray drying systems is
that no stack gas reheat is included in the spray drying
system. Unlike wet FGD systems, the spray drying
process does not result in saturated flue gas and the
need for reheat is reduced.
5.2.2 Design Basis and Costs
Costs presented in this section for utility lime spray
drying systems were adapted from estimates
developed by WA (10). Costs for industrial applications
were adapted from original estimates developed by
Radian Corporation (11). Each of these sources
contains estimates representative of recent lime
spray drying system design. Table 5-6 lists the major
design parameters for both the utility (10) and
industrial systems (11).
Costs presented in this section have been developed
for lime spray drying systems applied to boilers firing
a relatively low sulfur (0.7 percent coal. This is in
contrast to the costs presented earlier for wet FGD
systems which were based on a 3.5 percent sulfur
coal. The primary reason for limiting the cases
examined to the low sulfur coal is the lack of
documented information on application of spray
drying to high sulfur coal-fired boilers. _ No utility
systems have been sold for high sulfur units (greater
San 3 perent sulfur coal). The TVA has developed
some estimates for high sulfur utility applications.
These costs are discussed in Section 5.2.3.
Total capital investment, net annual operating
expenses, and unit annualized cost for utility systems
are presented in Figures 5-13, 5-14 and 5-15
respectively. The corresponding costs for industrial
Utility systems (10)
• Cost estimates are for new units.
• costs are based on 70% SOE removal (0.6 lb/1 06 Btu control ed
emissions) and a low sulfur eastern coal with the following
properties: 0.7% S, 1 5% ash, 1 1 ,700 Btu/lb.
• Plant heat rate is 9500 Btu/kWh.
• Costs are derived from TVA 500 MWe case. Curves based on
calculations for 200, 500, and 1000 MWe cases
• Spray dryers have rotary atomizers; 84% of gas ,s treated in
spray dryers at 83% removal, for an overall SO.removal of 7
-------
Figure 5-13. Lime spray drying flue gas desulfurization
systems for utility boilers - Total capital
investment (March, 1980 dollars).
Coal sulfur content, 3.5%; 90% removal
Coal sulfur content, 0.7%; 70% removal _____
250
GENERATING CAPACITY, MWe
FIRING RATE, 106 Btu/hr
GAS FLOW RATE, 1Q6acfm
industrial systems generally do not have the
extensive redundancy or stack gas reheat
typica"y included with utility
• industrial system equipment is likely to be shop-
fabncated rather than field-erected.
For spray drying/fabric filter systems another
difference may be m the type of fabric filter selected
Due primarily to pressure drop and bag-wear
considerations, utility systems will generally have a
reverse-air fabric filter. However, in indu^uS
soSch^rhere,PreSSU/e drop ''^derations are not
so critical, a pulse-jet fabric filter is sometimes used
The .capital costs of a pulse-jet fabric filter are less
£f£ ^verse-a.r unit of the same capacity.* (See
Section 4.3 in this report.)
Figure 5-14. Lime spray drying flue gas desulfurization
systems for utility boilers - Net annual
operating expenses (March, 1980 dollars).
Coal sulfur content, 3.5%; 90% removal
Gas flow rate for 3.5% S coal is 082 times the
shown on the scale below. e
Coal sulfur content, 0.7%; 70% removal
50,
200 400 600 800
GENERATING CAPACITY, MWe
1000
9500
FIRING RATE, 1Q6 Btu/hr
GAS FLOW RATE, 106 acfm
Heating value and moisture content, as well as the
excess a.rratetotheboiler.impacttheamount of flue
rnmhMctmUS?,e treated in the sprav drV|n9 ^tem.
Combustion of low rank western coals or lignite can
M m wTb°Ut ' ° t0 3° Percent hJ9her ^eg'as flows
(10) with a corresponding increase in the size and
cost of the spray drying and solids removal equip-
1 1 i"n \,
Heating value and moisture content
• Fuel sulfur content.
• Fuel ash content.
Available alkalinity in the fly ash
The fuel sulfur content also affects costs of the spray
drying systems. A higher fuel sulfur content results
in a direct increase in fresh lime requirements and
also increases the amount of waste solids that must
be disposed of. In addition, the stoichiometric ratio of
fresh reagent to inlet S02to achieve a given removal
increases as the inlet S02 concentration increases
dA Thus an increased fuel sulfur content will
^H0,''6 i'?,r9er feed handlin9 ™d preparation system
and landfill area and will result in increased annual
reagent and waste disposal costs.
te 5,-13 thr°Ugh 5'15 show a Comparison of
costs for lime spray drying systems applied to high
anpMow sulfur coal utility boilers.f The high sulfur
ycle' but no ^ bypa» for
78
-------
Figure 5-15. Lime spray drying flue gas desulfurization
systems for utility boilers • Unit annualized
cost (March, 1980 dollars).
Coal sulfur content, 3.5%; 90% removal "••
Gas flow rate for 3.5% S coal is 0.82 times the rate shown
on the scale below.
Coal sulfur content, 0.7%; 70% removal
CO
o
o
Nf
•^- a)
< 0
K
2
:
-
-
Mil III!
MM 1 III
— •' —
^^
1 1 1 1 1 1 III
II 1 II Ml 1
Illl Ill]
MM MM
lilt 1 M 1
-
—
-
-
[ ~
200 400 600 800
GENERATING CAPACITY, MWe
1900
3800
5700
I
7600
I
1000
9500
FIRING RATE, 106 Btu/hr
0
0.68
1.36
I
2.04
—I
2.72
I
3.40
GAS FLOW RATE, 10^ acfm
case is based on a lime-to-SOs stoichiometry of 1.6
and 90 percent removal; whereas, the low sulfur case
costs are based on a 1.1 stoichiometry and 70 percent
S02 removal.
Stoichiometric requirements for high S02 removal in
high sulfur coal applications are not well-documented.
No utility systems have been sold for high sulfur coal
units. And, although at least two industrial spray
drying systems treating high sulfur flue gas have
been sold, no data on the stoichiometric requirements
have been reported. Thus, there is substantial
uncertainty regarding reagent-related costs for high
sulfur applications of spray drying.
The TVA estimates that a 20 percent increase in lime
stoichiometry would result in about a 7.5 percent
increase in unit annualized cost for a high sulfur coal
application, and about a 2 percent increase for low
sulfur applications (10).
Waste solids collected from the system include fly ash
along with waste solids from the spray dryer. The
volume of waste to be disposed of and capital and
operating costs associated with landfill are thus
Figure 5-16. Lime spray drying flue gas desulfurization
systems for industrial boilers • Total capital
investment (March, 1980 dollars).
Coal sulfur content, 0.7%; 70% removal
10.0
i-
•z.
LU
5
I- co
« «
LU 2
5°
z-o
rf°
tS
o. o
< =
51
<
o
00
b
6.0
*»
'o
N>
o
100 200 300 400
FIRING RATE, 106 Btu/hr
41
82
124
165
i
500
206
i
GAS FLOW RATE, thousand acfm
increased as the ash content (fly ash emissions) from
the coal is increased.
The availability of alkaline species in the fly ash to
react with 862 in the spray dryer can substantially
reduce fresh lime requirements (13). One method
used to take advantage of the fly ash alkalinity is to
recycle some of the waste solid/fly ash mixture back
to the spray dryer. This operating method also results
in recycle of unreacted lime in the waste solids.
Although solids recycle is not included in the costs
presented here, there are cases where the cost of the
recycle equipment can be offset by the resulting
reduced costs for lime. Specifically, applications with
high lime stoichiometric requirements (high sulfur
applications) or those in which the fly ash has high
available alkalinity are instances in which solids
recycle may be of significant benefit.
An ESP can be used in a spray drying system instead
of a fabric filter. The choice depends on user
preference and site-specific factors such as fly ash
resistivity, ESP inlet dust loading, and pressure drop
considerations. The ESP may or may not be more
economical in some cases than the fabric filter; the
comparison is highly site-specific.
79
-------
Figure 5-17. Lime spray drying flue gas desulfurization
systems for industrial boilers - Net annual
operating expenses (March, 1980 dollars).
Coal sulfur content, 0.7%; 70% removal
*
LJJ
1.0
0.8
0.6
jnr|im
£1
Oo 0.4
< E 0.2
I I II I M
iiii|iiiL
100 200 300 400
FIRING RATE, 106Btu/hr
41
82
124
165
500
206
GAS FLOW RATE, thousand acfm
References - Section 5
Wet Scrubbing Systems
1. U.S. Environmental Protection Agency. Appendix
A: Compilation of Air Pollutant Emission Factors,
AP-42. Office of Air Quality Planning and
Standards, Research Triangle Park, NC. February
1980. p. A-2.
2. Anderson, K.D., et al. (TVA) Definitive SO* Control
Process Evaluations: Limestone, Lime, and
Magnesia FGD Processes, EPA-600/7-80-001,
PB80-196314*. Prepared for U.S. Environmental
Protection Agency, Washington, DC, January
1980, 296 pp.
3. Dickerman, J.C., and K.L. Johnson. (Radian Corp.)
Technology Assessment Report for Industrial
Boiler Applications: Flue Gas Desulfurization, EPA-
600/7-79- 178i, PB80-150873*. Prepared for U.S.
Environmental Protection Agency, Washington,
DC, November 1979.
4. Smith, M., et al. (PEDCo Environmental, Inc.) EPA
Utility FGD Survey: April-June 1980, EPA-600/7-
80-029c, PB80-226335*. Prepared for U.S.
Environmental Protection Agency, Washington,
DC, July 1980, Appendix A, pp. A-1 through A-25.
5. Tomlinson, S.V., et al. {TVA) Definitive SOX Control
Process Evaluations: Limestone, Double Alkali,
and Citrate FGD Processes, EPA-600/7-79-177,
PB80-105828*. Prepared for U.S. Environmental
•Available for purchase from the National Technical Information Service, 5285
Port Royal Road, Springfield, VA 22161.
Figure 5-18. Lime spray drying flue gas desulfurization
systems for industrial boilers • Unit annualized
cost (March, 1980 dollars).
Coal sulfur content, 0.7%; 70% removal
UNIT ANNUALIZED COST
cents per million Btu
g 8 8 8 I
Jill 1 1 1 1
r
:
INI I 1 I 1
X
^
1 1 1 1 Mil
^^
i i i i i i i i
N II 1 1 II
1 1 II | 1 II L
-E
-E
-^
-E
100 200 300 400 5C
FIRING RATE, 106 Btu/hr
41
82
124
165
206
GAS FLOW RATE, thousand acfm
Protection Agency, Washington, DC, August 1979
236 pp.
6. Gibbs, LL {PEDCo Environmental, Inc.) Paniculate
and Sulfur Dioxide Emission Control Costs for
Large Coal-Fired Boilers, EPA-450/3-78-007, PB
281 271. Prepared for U.S. Environmental
Protection Agency, Office of Air Quality Planning
and Standards, Research Triangle Park, NC,
February 1978, 168pp.
7. McGlamery, G.G., et al. (TVA) FGD Economics in
1980. In Proceedings: Symposium on Flue Gas
Desulfurization - Houston, October 1980; Vol. 1,
EPA-600/9-81-019a, PB 81-243 156. April 1981,
pp. 49-83.
8. Barrier, J.W. et al. {TVA) Economics of Disposal of
Lime/Limestone Scrubbing Wastes: Sludge/Fly
Ash Blending and Gypsum Systems, EPA-600/7-
79-069, PB 297 946*. Prepared for U.S. Environ-
mental Protection Agency, Washington, DC,
February 1979, p. xxvii.
Spray Drying Systems
9. Kelly, M.E., and S.A. Shareff. (Radian Corp.)Third
Survey of Dry S02 Control Systems. EPA-600/7-
81-097, PB 81-218976*, Prepared for U.S.
Environmental Protection Agency, Research
Triangle Park, NC, June 1981. p. 15-16.
1.0. Burnett, T.A., andK.D.Anderson.(TVA)Technical
Review of Dry FGD Systems and Economic
Evaluation of Spray Dryer FGD systems. EPA-
-------
600/7-81-014, PB81-206476*. Prepared for
U.S. Environmental Protection Agency, Research
Triangle Park, NC, February 1981. p. 91-235.
11. Jennings, M.S., and M.E. Kelly. {Radian Corp.)
Costs of Sulfur Oxide and Paniculate Matter
Emission Control for Coal- and Oil-Fired
Industrial Boilers. EPA Contract 68-02-3058;
ESED Project 76/13. Prepared for U.S. Environ-
mental Pretection Agency, Research Triangle
Park, NC, August 21, 1981. p. 2-1 to 2-32.
12. Apple, C. and M.E. Kelly. (Radian Corp.)
Mechanisms of Dry S02 Control Processes. EPA-
600/7-82-026, PB 82-196924*. Prepared for
U.S. Environmental Protection Agency, Research
Triangle Park, NC, April 1982. p. 44-53.
13. Gibson, E.D., M.A. Palazzolo, and M.E. Kelly.
(Radian Corp.) Summary Report: Sulfur Oxides
Control Technology Series: Flue Gas Desulfuriza-
tion Spray Drying Process. EPA Contract 68-02-
3171, Task 37. Prepared for U.S. Environmental
Protection Agency, Research Triangle Park NC,
September 15, 1981.
'Available for purchase from the National Technical Information Service,
5285 Port Royal Road, Springfield, VA 22161.
81
-------
Appendix A
Methods for Adjusting Data
The cost data in this report were derived from cost data
in existing published sources. These data were
adjusted to conform to the format used in this report,
to reflect total system costs rather than individual
system component costs, and to update costs from a
variety of price years to the common reference time of
March 1980. The exact method used for adjusting
data varied depending on the form of the original data.
For some technologies, well documented costs for
total systems were already available. For other
technologies, estimates had to be prepared from
individual component costs that were available in the
literature. This varied between the four major
technology areas of this report as well as between
individual technologies within a technology area.
The following sections describe the format, cost
factors, and unit prices used to develop system costs;
methods and cost indices to update costs; and special
considerations in using published cost data by
technology area.
A.1 Format, Cost Factors, and Unit
Prices
The format for presenting all cost data in this report is
based on an earlier report by Uhl(1). All capital
investment costs are presented as total capital
investment and annual costs are presented both as
net annual operating expenses and unit annualized
cost. Table A-1 defines the cost elements comprising
total capital investment as used here. Table A-2
defines net annual operating expenses. For a de-
tailed discussion of cost elements the reader is re-
ferred to the report by Uhl{1). Unit annualized cost is
derived from net annual operating expenses as
explained in Section A.2
In addition to listing the cost elements, the tables also
contain cost element item numbers assigned to those
line items in the Uhl report, as well as cost factors
used in the present work to derive the various cost
elements from preceding line items by factoring as
discussed next.
The computation of total capital investment as shown
in Table A-1 begins with the total direct cost-forthe
system under consideration. This total direct cost is
the total direct installed cost of all capital equipment
comprising the system. In some references, especially
for water and wastewater treatment systems, this
cost is referred to as total construction cost. Some
authors use other names for this line item. Depending
on the reference and the technology, the direct capital
cost was available or was derived from untnstalled
equipment costs by computing costs of installation
separately. Literature costs were updated to March
1980 using capital cost indices. These indices are
discussed in Section A.3. To obtain the total capital
investment, other costs must be added to the total
direct cost. A standard procedure of cost estimating is
to obtain these other costs by factoring.
The first group of other cost elements is indirect costs.
These include engineering and supervision, field
construction expenses, and various other expenses
such as general project administration and legal fees,
for example. These costs are computed by multiplying
total direct costs by a factor as shown in Table A-1.
The factor is approximate, is obtained from the cost
literature, and is based on previous experience with
capital projects of a similar nature. This is true also for
the factors for other cost elements shown in the table.
Factors can have a range of values and vary according
to technology area and for individual technologies
within an area. Appropriate factors were selected for
use in this report based on the authors'judgment and
experience.
When the indirect costs are added to the total direct
costs, total bare module cost is obtained. The cost
elements in the next group are obtained by applying
factors to the total bare module cost. These cost
elements are added to the total bare module cost to
obtain total plant cost. Some additional cost elements
can be calculated from the total plant cost by applying
factors. These additional cost elements can include
interest during construction and start-up costs if
these costs are included as part of the total capital
investment.* If these costs are capitalized, as they are
in this report, they are added to the total plant cost to
obtain the total depreciable investment (sometimes
referred to as total fixed capital as well as other
names). The total depreciable investment is used in
calculating the unit annualized cost discussed in
Section A.2.
*This is an option that depends on accounting practices of individual
organizations. If these costs are not capitalized they are treated as an
expense, in the first year of operation, for example.
82
-------
Table A-1. Format and Factors for Total Capital Investment3
Technology area_
Particulate
matter
control'
Flue gas
desulfurization
individual cost items vary widely from technology to technology
12-20 Indirect cost items
(Engineering and super-
vision, construction
and field expenses,
other)
21 TOTAL BARE MODULE COST
22
23
27
24-26,
28-30
31
Contingency
Contractor's fee
Retrofit increment
Other
TOTAL PLANT COST
32 Interest during
construction11
33 Start-up
34 Other
35 TOTAL DEPRECIABLE
INVESTMENT
36 Land
37 Working capital
38-40 Other
41 TOTAL CAPITAL
INVESTMENT
0.15
Sum of
11-20
0.15
0.10
Sum of
21-30
0.12
0.05
Sum of
31-34
S2000/acre
0.10
Sum of
35-40
0.15
Sum of
11-20
0.15
0.10
Sum of
21-30
0.12
0.05
Sum of
31-34
S2000/acre
0.10
Sum of
35-40
0.300.200.150.30 0.24
Sum of Sum of
11-20 11-20
0 100.100.100.10 0.21
0100.050.050.10 0.04
Sum of Sum of
21-30 21-30
0.120.030.030.12 0.19
0.05 0.01 0.01 0.05 0.08
0.24
Sum of
11-20
0.21
0.04
Sum of
21-30
0.19
0.08
Sum of
31-34
S2000/acre
0.10 -( -1 0.10
Sum of Sum of
31-35 31-35
$2000/acre
Sum of Sum of Sum of
35.40 35-40 35-40
£ SiplS byTOTAL BARE MODULEI COST to ob°ain the contingency line item for drinking water systems.
"Refers to line item code.proposedjn report by Uhl 0) . = ws = ^ scrubbers
PTndudTng such components as piping, insulation, electrical work, mstrumentat.on,
s^
•Working capital for ESP, FF, and FGD systems was computed as 25^ of processing expenses
DEPRECIABLE INVESTMENT.
Finally, the capital requirements for land and working
capital are added to the total depreciable investment
to obtain total capital investment. In this report
estimated land requirements and a unit price of
$2000 per acre were used to calculate the land cost
for each technology. Working capital can be
computed in a number of different ways. Here it was
estimated as a percentage of total depreciable
investment except for ESP, FF, and FGD systems
where it was calculated as a percentage of processing
expenses.
Cost elements for net annual operating expenses are
shown in Table A-2. Direct cost elements are added
together to yield processing expenses. Some
references refer to these expenses as operating and
maintenance costs. Values for these cost elements
were obtained from the literature and updated using
unit prices for March 1980 given in Table A-3. This
was usually accomplished by ratioing new unit prices
to the old and multiplying by the reported annual
value for that cost element. In some casesthe annual
value for a cost element was calculated directly from
the operating requirement (e.g., labor hours per year)
multiplied by the unit price. The method used
depended on how data were presented in the
literature source. Overhead was calculated as a
fraction of labor costs. Insurance, property taxes, and
general expenses were calculated as a fraction of
total depreciable investment.
A.2 Unit Annual/zed Cost Calculations
Unit annualized cost is derived from net annual
operating expenses and capital changes asdiscussed
in the next paragraph. The annualized cost is first
calculated and then divided by system capacity to
83
-------
TableA-2. Format for Net Annual Operating Expenses TableA-3.
Item
No.
53
56-58. 61
59. 60
62
63
64
65
66
67
68,69
70
74
76
80
87
88-89
90
,, '—
ltem Exolanation
Raw materials
Labor"
Materials"
Steam
Power (Electricity)
Compressed air
Fuel
Waste disposal
Other
Computed as annual
multiplied by unit price.
PROCESSING EXPENSES Sum of items 53-69 (except
54, 55)
Overhead 50% of labor;
. 65% of labor for ESP FP=
Insurance and property taxes 1 % of TOTAL DEPRECIABLE
INVESTMENT (35)
NET OPERATING COSTS 9nm ni itn™^ -in in o -m
— , ^ oum or items /U, /4, & 76
General expense 4% of TOTAL DEPRECIABLE
Other INVESTMENT (35)
NET ANNUAL OPERATING EXPENSES Sum of items 80-89 (except
. 81-86)
Unit Prices Employed for Net Annual Operating
Expenses"
materials categories. ™i««*«i separately m the labor and
£or FGD systems; 60% of processing expenses less utilities
ESP = electrostatic precipitator; FF = fabric filter.
yield cost per unit of capacity. Conversion factors are
applied as necessary to express the result in
appropriate units. For example, the annualized cost
for a wastewater technology expressed as millions of
dollars per year is divided by system capacity in
millions of gallons per day and adjusted with
appropriate conversion factors to obtain the unit
annualized cost in cents per thousand gallons.
The annualized cost corresponds to a uniform annual
revenue requirement to cover both net annual
operating expenses as well as capital recovery, return
on investment, and income taxes. The capital
recovery, return on investment, and resulting income
tax requirements are directly related to the capital
investment and are referred to as capital charges.*
The net annual operating expense cost elements of
insurance, property taxes, and general expenses,
when derived from capital investment by factoring as
they were in this report, can also be considered
capital charges. Because the capital investment is
fixed, these capital charges are also referred to as
fixed charges. Income tax is included with capital
charges as a fixed charge. The remaining cost
elements of net annual operating expenses, such as
labor, are variable because they can change with the
level of operation of the system, and can be referred to
as variable charges. The annualized cost is, therefore
the sum of the variable and fixed annual charges for
the technology.
The fixed annual charges can be computed by
different methods. Here the fixed charge rate method
is related to methods employed by the Electric Power
Research Institute (EPRI), the Jet Propulsion
"Capital recovery and return on investment are otfen expressed in a
numerically equivalent form as depreciation and interest. Preferred
terminology depends on perspective; whether the charges are viewed from
an investor s, borrower's, or lender's viewpoint.
84
1. Direct labor rate, S/hr
2. Energy costs
Electric power, $/kWh
Fuel oil, S/gal.
Natural gas, S/106Btu
Gasoline, S/gal.
3. Land, $/acre
4. Chemical costs
Chlorine, $/ton
Limestone, S/ton
Agricultural limestone, S/ton
Lime, S/ton
Soda Ash, S/ton
Magnesium oxide, S/ton
Ferric chloride, S/ton
Alum, $/ton
Sodium chlorite, $/ton
Ammonia:
Anhydrous, S/ton
Aqueous, S/ton
Activated carbon (granulated), S/lb
Sulfuric acid (credit for FGD
systems), S/ton
Catalyst (Mag-Ox FGD process), S/liter
Fixation chemicals (FGD L/LS/DA
processes), S/ton
5. Other unit costs
Process water, S/1000 gal.
Steam, $/106Btu
Waste disposal {sludge handling
utility FGD systems), $/ton-mile
Waste disposal (sludge handling
industrial boiler FGD systems
and particulate matter
technologies), S/ton
=11.40
= 0.04
= 0.60
= 2.12
= 1.23
= 2000
= 300
8
= 15
= 40
= 90
= 300
= 100
= 72
- 97
= 130
= 175
= 0.50
= 25.00
= 2.50
= 20
= 0.12
= 2.00
= 2.00
= 15.00
"Applicable to March 1980.
Laboratory {JPL), and the Mitre Division of the Mitre
Corporation (2, 3, 4). Doane et al. (3) discusses the
procedure by JPL for calculating fixed charge rate
FCR, which has been recommended for use in this
report by Uhl (5).
The fixed charge rate is multiplied by the total
depreciable investment to obtain the fixed annual
charges as a single number. The fixed annual charges
are added to the variable annual charges, as
discussed above, to obtain annualized cost In
equation form,
AC = FCR x TDI + VAC
where AC = annualized cost
FCR = fixed charge rate
TDI = total depreciable investment, and
VAC = variable annual charges.
The unit annualized cost is then,
UA = AC/CAP
where UA = unit annualized cost, and
CAP = system operating capacity.
Based on the discussion by Doane et al. (3), the FCR is
found from,
FCR =CRFk,N
1-r
.n-g 1
J
-------
where
CRFM =
the capital recovery factor
computed at cost of capital k
over N years
the capital recovery factor
computed at cost of capital k
over n years
k = after-tax cost of capital or
internal rate of return
n = taxable life
N = system book lifetime
T = income tax rate expressed as a deci-
mal fraction
DPFmkn =depreciation factor for Tin-
type depreciation, at an after-
tax cost of capital, k, over n
years accounting or taxable
lifetime
a = investment tax credit, and
fij(j=1,2,3) miscellaneous fixed charges
of insurance, property taxes,
general and administrative
expenses.
The after-tax cost of capital is found from,
_ f* n
v v v
where kd=the cost of debt capital
kc=common stockholder s rate of return
on investment and therefore the cost
of common equity capital
kp=preferred stockholder's rate of re-
turn on investment and therefore
the cost of preferred equity capital
D/V=ratio of debt to total capitalization
C/V=ratio of common stock to total capi-
talization, and
P/V=ratio of preferred stock to total capi-
talization.
One of the several equivalent algebraic forms for
capital recovery factor is,
J= k
1-0+k)"
The depreciation factor DPFmXi- depends on m, the
depreciation method used (e.g., straight line, sum-of-
the-years digit, or others). When straight Ine
depreciation is used, as was done in this report, the
factor is, p -• _n
DPFSi,k,n = Ln'CRFk'nJ
The financial premises used in calculating the fixed
charge rate for each technology in this report are
gTven in Table A-4. Also given are the resulting value
for weighted after-tax .cost of capital and several
SnS including the first) for the fixed charge rate
equations. Calculations are based on a system book
lifetime of 20 years and a tax life of 10 years.
The basis for these assumptions is as f ol lows. I merest
on debt financing of 1 3 percent was assumed typical
of rates paid by private companies in non-regulated
industries* and 14 percent by regulated industries
(eq utilities). For municipal projects, 10 percent
reflects investor acceptance of a lower rate of return
on tax-free bonds than for taxable corporate debt
instruments. For non-regulated private industry, a
common stockholder return of 14 Percent was
assumed, which reflects a combined typ.ca common
stock dividend rate and an expected capital gain. For
regulated private industry, such as electric utilities, a
total equity return of 12 percent was assumed to
reflect the higher dividend rate and lower overall risk
associated with utilities.
The financing mix assumed for each technology
reflects the most likely use of that technology by
economic sector. Drinking water systems are usually
pubHc projects financed by bonded debt. Wastewater
projects can be either public or private. For pub he
projects, all financing was assumed to be by bonded
debt For private companies the assumption was 2.*
percent financing by debt and 75 percent by equity-
Paniculate control would most likely be used by either
non-regulated industry or regulated industry m the
illustration of the non-regulated private economic sector.
Table A-4.
Basis for Fixed Charge Rate Annualized Cost Calculations
Paniculate
control
Flue gas
desulfurization
Non-regulated
industry
Regulated
industry
Non-regulated
industry
aFirsttermFCR=CRFk,N
Regulated
industry
-rxDPF9i.k.n-tt"|
1 -r -I
25% debt
75% equity
50% debt
50% equity
25% debt
75% equity
50% debt
50% equity
with cr = 0.10.
0.13 0.14 0.12
0.14 0.12 0.10 20 10 0.116 0.161 0.621 0.132
0.13 0.14 0.14 0.20 10 0.136 0.179 0.559 0.162
0.14 0.12 0.10
0.116- 0.161 0.621 0.132
-------
sector. For non-regulated industry a 25
debt, 75 percent equity financing mix was
to be 50 percent debt, 50 percenrequTtyS
frr *** mat6rial- ^hich W3S Updated
from literature reported values using the Producer
Price Index for Finished Goods (6).
PI . — r""*"*m vjcwi, uu percent equity
indust^M^ is Pnmarily a regulated Jab'e A;5 lists annual averages for the three capital
deb^SO De St f . ?9y; therefore- a 50 percent cost 'ndlces from 1970 through 1979 as well as end-
aeot, bo percent equity financing was assumed. of-quarter values (last month of the quarter) from
'vidrcn i y / / tnroj \c\rt Jv/1 ar*^^* 1 oo/t
— v t f ki«iv/uui| IVIoiUlt J wOU
pe
debt, 50 percent equity financing was assumed.
Updating Costs
Cost are updated from one base year to a new base
V T* C°St indices' Cost indices are
reflect relative price levels between
anT * "^ °f different
and are published in a number of
references. These include indices for capTtafcos
that mT'un35 We" 3S ad'ustmen* ^r coCnents
tnat make up operattng expenses. The use of met
•nd.ce. ,s illustrated by the following
newcost value =old cost valuex new cost index valng
old cost index value
Two capital cost indices used in this report are the-
eWS Rec°rd C
• Chemical Engineering ICE) Plant Cost Index.
The first is published weekly in Engineering News
Kr8??- The SeC°nd iS P"^shld bfweek'y
rn Chemtcal Engmeering magazine Both
publications of McGraw-Hill, Inc of New York
In the preparation of this report, costs from
March* '9°SS crne,Tdated,'° the ^™e o
march 1 980. Capital costs for water and wastewater
"dated U ™
A.4 Interest During Construction
The capital costs of a project are paid by borrowina
money for the entire project, financing the em"I
n ? "2 lr°T 'mernal funds' or fina"<=ina Part of hi
project by borrowing and part from internal funds
Hnanctr5' Char96S "^"t^ with construction
financing are sometimes capitalized and so can be a
significant component of total capital investment
The interest during construction is the cost of capital
p?r,rwh±rhtheprojrdu^
period. Whether the capital is borrowed or internal
±7 1S .?" 3 C°St for usi"9 the «*Ph»l. For borrowed
caprtal, the cost is clearly the interest charged Ta
lender For internal capital, the interest rate is
eaTi* r^°Hthe "", °f retum that the «5«l »u3
earn if placed in an alternative investment such as a
loan to a borrower. Therefore, the cost of captal can
be viewed either as interest on a loan or a
Tab.eA-5. Annual Average and End-of-Quarter Capital Cost Indices
The cost for interest during construction depends on
and sch^ ."I' Jen9th of the Construction period
period ^ A1, Ll ?nCm9 durin9 the Construction
period. A 12 percent per year interest rate was used
throughout this report for the construction fl^SnS?
ESPanSFFr?nT-Pe,riod Was 18 ™n*hs except for
fcSP and FF in paniculate control and FGD technolooies
which were 3 months and 30 months, respectivlly
Financial schedule becomes important for larae
projects extending for many months or several years
Annual
average
1386
1581
1753
1895
2019
2209
2400
2610
2811a
3051
Engineering News-Record
Construction Cost Index
(1913=100)
Mar. June Sept. Dec
Year
1970
1971
1972
1973
1974
1975
1976
1977 2610 2514
978 2811- 2698
1979 3051 2886
1180 -_. 3150 -
"Estimated by averaging end-of-quarter indices.
2574
2822
3054
2675
2851
3132
2676
2872
3131
Annual
_average
126
132
137
144
165
182
192
204
Chemical Engineering
Plant Cost Index
(1969=100)
Mar. June Sept. Dec.
199 202
o
237
253
243
209
223
248
210
226
239
EPA Sewage Treatment Plant
Construction Cost Index
(1957-59=100)
Annual
average Mar. June Sept. Dec.
144 '
160
172
783
217
250
262
278 271 274 281 288
305 290 303 311 314
322 334 338
86
-------
These projects draw the necessary funds to pay for
construction at selected intervals throughout the
project rather than all at once. Individual projects
have their own specific schedules. For this report,
however, for all projects it was assumed that the
construciton payment schedule was divided into
thirds. One-third of the total funds were required for
each third of the toal construction period and were
dispersed at the beginning of each period. Another
method, sometimes used in utility financing, is to
assume that one-fourth of the funds are dispersed
during the first and last thirds of the construction
interval, and half are dispersed during the second
third of the project construction interval. Still another
approach includes the assumption that funds are
dispersed half way through each third of the
construction period rather than at the beginning of
each third. This approach will result in lower charges
for interest than the assumption that funds are
borrowed at the beginning of each load period.
The interest rate and funding schedules discussed
above determine the amount of money required for
interest charges during a construction project. Table
A-6 shows the interest factors for different annual
interest rates and construction periods based on the
three-thirds schedule discussed above. To obtain the
cost of interest during construction, multiply the
appropriate factor by total plant cost (see Table A-1).
Table A-6. Factors for Calculating Interest During Construc-
tion3
period (months)
6
12
18
36
10
0.03
0.07
0.10
0.21
12
0.04
0.08
0.12
0.26
14
0.04
0.09
0.14
0.31
Locality factors for power costs by census region
rather than major cities are provided in Table A-8 (7).
TableA-7. Cost Locality Factors (7)
'Uased on three-thirds loan schedule.
A.5 Location Factors
Construction costs vary geographically due to
differences in costs of materials and labor. A sample
of this cost variation for wastewater treatment is
provided in Table A-7 (7). These construction cost
values were derived from calculations using the EPA
Sewage Treatment Plant and Sewer Construction
Cost Index and should only be used for rough
estimates of the geographic influence on capital
investment variations for wastewater and drinking
water systems. The similarity of drinking water plant
construction to that for wastewater treatment plants
justifies its use for the former. The labor cost values
for plant operating labor were based on a calculation
using average earnings from the U.S. Bureau of
Census (7).
Similar compilations of factors for paniculate matter
control and flue gas desulf urization systems were not
available at the time this report was written.
Atlanta
Baltimore
Birmingham
Boston
Chicago
Cincinnati
Cleveland
Dallas
Denver
Detroit
Kansas City
Los Angeles
Minneapolis
New Orleans
New York
Philadelphia
Pittsburgh
St. Louis
San Francisco
Seattle
NATIONAL INDEX VALUES
Construction
0.79
0.92
0.79
1.04
1.20
1.08
1.13
0.70
0.87
1.10
1.07
1.17
0.97
0.94
1.24
1.15
1.02
1.18
1.13
1.07
1.00
Labor
0.77
0.79
0.79
0.97
1.02
0.98
1.05
0.92
1.00
1.32
0.88
1.32
1.21
0.66
1.14
1.05
0.87
0.83
1.13
1.21
1.00
Table A-8. Power Cost Locality Factor (7)
New England
Mid-Atlantic
East North Central
West North Central
South Atlantic
East South Central
West South Central
Mountain
Pacific
U.S. Average
1.31
14 Q
.18
1.10
0.98
0.94
0.98
0.87
0.79
0.86
1.00
References - Appendix A
Uhl, V.W. A Standard Procedure for Cost Analysis
of Pollution Control Operations. Vol. I. User Guide,
EPA-600/8-79-018a (PB80-108038*). Vol. II
Appendices, EPA-600/8-79-018b (PB80-108046*).
U.S. Environmental Protection Agency, Industrial
Environmental Research Laboratory, Research
Triangle Park, NC, June 1979.
Rudasill, C. Revenue Requirements Calculations
for Utility Systems Analysis. Paper presented at
the ERDA/METRIC Engineering-Economic Analysis
Workshop, the MITRE Corporation/METREK
Division, McLean, VA, April 4-5, 1977.
Doane, J.W., R.P. OToole, R.G. Chamberlain, P.B.
Bos, and P.O. Mayevck. The Cost of Energy from
Utility-Owned Solar Electric Systems: A Required
Revenue Methodology from ERDA/EPRI Evaluations.
•Available for purchase from the National Technical Information Service,
5285 Port Royal Road, Springfield, VA 22161.
87
-------
JPL Report No. 5040-29 (ERDA/JPL-1012-76/3)
Pasadena, CA, June 1976, 82 pp.
Bennington, G.E. Ten Steps to Busbar Costs. WP-
11488, The MITRE Corporation/METREK Division
McLean, VA, May 1, 1976.
Uhl, V.W. Calculations of Annualized Costs Using
the Fixed Charge Rate Method. Private Communi-
cation. September 1980.
U.S. Department of Labor Monthly Energy Review
DOE/IA 0035/05(08).
U.S. Environmental Protection Agency, Office of
Water and Waste Management, Washington DC
Innovative and Alternative Technology Assessment
Manual, EPA-430/9-78-009, February 1980
88
-------
Appendix B
Glossary
This glossary is presented as an aid to the
identification of selected specialized terms which
sometimes cause confusion or with which the user
might not be familiar.
annual operating expenses: Includes operating and
maintenance costs as well as capital related
charges except except interest or return on capital.
See expenses. .
annualized cost: The equivalent annual cost equal to
the revenue requirement. Includes annual operating
expenses plus interest and return on capital.
backwash: In granular media filtration or activated
carbon treatment the reverse flow of clean water
through the system to dislodge and remove solids
that have accumulated in the bed.
biochemical oxygen demand:Ameasureofbiodegrad-
able organic pollutant content of wastewater
expressed as mg/l of oxygen required using a
standard test.
capital investment: Investment for long-term use
(over a year), which is therefore capitalized.
capital structure: The proportionate portions of
capital from sources such as common stock equity,
preferred stock equity, and debt (bonds).
capitalize: To consider as an investment; it can either
be depreciated {buildings and-equipment) or
recovered (land or working capital).
cash flow: Annual cash receipts in the form of net
profit (after taxes) plus the depreciation charge;
also called cash inflow and cash flowback. For
comparisons of alternatives with the same
revenue, it can be the depreciation charge plus net
saving or minus extra net operating charge
adjusted for income taxes.
cash flows: The various sources and outlays for funds
in an active project.
conceptual estimate: An estimate for a new process
or operation, one that has not been built or operated
constant worth dollars: [Current dollars] x[1 + annual
inflation ratef"*1. where n is the number of years
from the year in question to the reference year
Sometimes these are termed constant dollars real
dollars, or deflated dollars. For an example calcula-
tion, see footnote.*
The 1975 value = [53.000,000] x [1 + 0.08] - 91,891,000 MS/s
constant worth dollars) (then-current dollars).
cost index: See inflation index.
current dollars: Dollars at any point in time.
depreciation: The allocation in a systematic and
rational manner of the cost of fixed capital assests
less salvage (if any), overthe estimated useful life of
the facility. , . ..
design flow rate: The flow rate for wh.ch equipment is
sized. Systems usually operate at less than the
design flow rate. . .
detention time: The residence time of drinking water
or wastewater in a process vessel during treatment.
discount rate: The interest rate used either to
discount future cash flows to a reference time {zero)
or to compound past cash flows to a specified
reference time. ,
discounted cash flow rate of return: See internal rate
of return. ,-*•„„«
engineering cost analysis: The application of
techniques to the expected cap.tal investments.
annual operating expenses, and other cash flows to
ascertain the economic feasibility of a project by
computing measures of merit.
equivalent annual cost: A generic term to describe
equivalent cash flows; it can be calculated either as
a uniform end-of-year value, or a uniform
continuous flow throughout the year.
equivalent annual value: A version of Jfqu.valen
annual cost used in evaluating public sector
qu.va.eni uniform cash flow or cost: Corresponds to
equivalent annual cash flow {or cost) when it is
calculated as a uniform end-of-year value.
escalation: Increase in the cost of a particular item as
distinct from general inflation. Escalation might be
due to price increases in constant dollars as well as
to inflation.
expenses: Net expenses are all payments transferred
{or paid) to entities outside the operating organiza-
tion for costs incurred for and related to the plant
operation; total expenses include depreciation
charges in addition to the above.
expensed: The accounting operation in which an
outlay is classified as an expense and included in an
account of expenses, generally classified by type;
e.g., operating labor, maintenance materials.
factored estimate: A form of capital cost estimate;
usually it is a form of study estimate.
figures of merit: See measures of merit.
89
-------
firing rate; The rate of fuel usage in boilers or other
direct-fired process equipment expressed in terms
of energy equivalent as Btu/hr
fixed capital: Corresponds to depreciable investment
(.buildings and equipment) plus land; excludes
working capital.
fixed charge rate: An expression of capital-related
tixed charges for a facility as dollars per year
general expense: An indirectly attributable expense
for administration, sales, research, and financing
activities. y
hydraulic loading: In granular media filtration or
activated carbon treatment the flow rate of liquid
applied to the granular bed expressed as gpm/ft2
IF: Symbol to denote total plant cost; usually equiva-
lent to the depreciable investment; corresponds to
total module cost.
L: See working capital.
inflation index: Also termed cost index; the relative
value of the dollar at a point in time in a particular
segment of the economy as compared to its value at
n * 'S arbitrari|V 9'ven
je o
interest, continuous: Interest computed by assuminq
an instantaneous time period for compounding
generally expressed as a nominal interest rate per
year. This nominal interest rate works out to be less
than the effective interest rate for the year
interest, discrete: Also termed simple interest-
interest on the principal for the period (usually 1
year). 7
interest rate of return: See internal rate of return
internal rate of return: (IROR) Rate of interest at
which outstanding investment is repaid by
proceeds of a project to achieve a zero present
worth; also, called interest rate of return
' and Profitabil'ty
non-regulated industry: An industry in the non-
regulated sector of the economy. See regulated
sector.
measures of merit: Also termed figures of merit cri-
teria for evaluation, and feasibility criteria- ratios
percentages, and other indices that characterize
the economic feasibility of a project; e.g., return on
original investment, payout time, internal rate of
return, and annualized cost
minimum acceptable rate of return: This is the lowest
return that will be considered attractive for the
investment of new capital; it is often taken as the
average current return on investment capital- it is
not to be confused with the cost of capital and
should be somewhat higher. Note that the kind of
return (e.g., ROI or IROR) needs to be specified
module: The major equipment items that carry out
either a unit operation (e.g., heat transfer,
distillation, solids separation) or a unit process (e q
biodegradation of liquid wastes)
net annual operating expenses: Operating and main-
tenance costs as well as capita I-related charges
except depreciation and interest.
0 and M: Direct operating and maintenance costs-
represent only a fraction of the total annual operat-
ing expenses. M
operating flow rate: The flow rate at which a facilty
actually operates, as opposed to the design flow
rate.
payout time: The time in years to recoup the fixed
(depreciable) capital from cash flow; also called
payback time or period.
present value: See present worth
present worth: The sum of the discounted (and com-
pounded) values of the cash flows for a given
project or operation. The discount rate must be
specified.
private sector: Refers to projects financed by private
capita I and for which the price of the output is set by
me market.
reactivation: The treatment of activated carbon to re-
move adsorbed organic material and restore its
adsorption capabilities.
regeneration: Another term for reactivation
regulated industry: See regulated sector
regulated sector: Refers to projects funded by private
capital, but for which the price of the output is
regulated by law or a government body. Examples
are electric utilities, the telephone company, and
public carriers.
reheat: Use of a heat exhanger or ^introduction of
some flue gas downstream from a gas scrubber to
ra.se the temperature of the gas to prevent
condensation of water vapor in the stack
^facilityEqU'Pment °r faC'lity added t0 an existin9
retrofit increment: The extra or added cost required
for a retrofit facility above that for the basic plant
total annual operating expenses: Operating and
maintenance costs as well as capital-related
charges include depreciation but not interest
total capital investment: The total capital required for
a project including various indirect costs such as
interest during construction, start-up costs where
capitalized, land cost, and working capital
unit cost: As applied to fixed investment - cost divided
by an appropriate output per year; as applied to
annual expenses - total expenses divided by output
per year; as applied to annualized cost - required
revenue divided by annual output. For the latter
case, the output may be discounted and escalated
in the same fashion as the costs
working capital: Funds in reserve necessary for the
normal conduct of business.
90
-------
Appendix C
Conversion of English to International System (SI)* Units
To Convert from:
To:
Multiply by:
Length
Area
Volume
Mass
Weight rate of flow
Vol. rate of flow
Energy
Power
Specific energy
Pressure
Water for energy
Heat rate
Temperature
Heat transfer
Coefficient
ft
ft2
acres
ft3
gal.
Ib
tons
105lb/fir
tons/ day
gal./min
gal./min
106gal./day
Btu
kW-hr
hp
kW
106Btu/hr
Btu/lb
Ib/in.2
gal./706Btu
Btu/kW-hr
°F
Btu/hr ft2 °F
meter
meters2
meters2
meters3
meters3
kilograms
megagrams
kg/sec
kg/sec
meiersVsec
millimetersVsec
meters3/ sec
kilojoule
(= Newton x meter)
megajoules
Joules/sec
Joules/sec
kilojoules/sec
kilojoules/kg
kilopascal
{= kilonewton/m2)
mVmegajoule
Joules/kW-sec
K
Joules/ secm2K
0.305
0.0929
4047
0.0283
0.00379
0.454
0.907
0.126
0.0105
6.309 x 10'E
6309
0.0438
1.055
3.60
746
1000
293
2.324
6.895
3.592 x 10"6
0.293
0.556 (°F + 459.7)
5.674
"Standard for Metric Practice, Amercian Society for Testing and Materials,
E3 80-76, 1976.
91
-------
Multiply
Appendix D
Miscellaneous Conversion Factors
By
To Obtain
acres
atmospheres
atmospheres
atmospheres
Btu
Btu
Btu
Btu
Btu/lb
cu ft
cu ft
cu ft
cu ft/second
cu ft/second
cu yd
°F
ft
gal.
gal., water
gpd/sq ft
gpm
gpm/sq ft
hp
hp
hp
hp-hr
in.
Ib (mass)
million gal.
mgd (million gal./day)
ppm (by weight)
psi
sqft
tons (short)
43,560
29.92
33.90
14.70
1.055
777.5
3.927 x 10~4
2.928x10^
2.326
28.32
0.03704
7.481
0.6463
448.8
0.765
0.555 <°F - 32)
0.3048
3.785
8.345
0.04074
0.06308
0.06790
0.7457
42.44
33.00
2.685
25.4
0.4536
3,785
3,785
1.000
6.985
0.0929
907.2
ft2
in. of mercury
ft of water
psi
kj
ft-lb
hp-hr
kW-hr
kJ/kg
liter
cu yd
gal.
mgd (million gal./day)
gpm
m3
°C
m
liter
Ib, water
mVm2 • day
liter/s
liter/m2 • s
kW
Btu/min
ft-lb/min
MJ
mm
kg
m3
mVd
mg/liter
kN/m2
m2
kg
Conversions between MWe, firing rate, and gas flow depend on
fuel and excess air used. For this report the factors used for
paniculate matter control and wet FGD systems are:
3200 acfm = 1 MWe
412acfm = 106Btu/hr
For spray drying FGD the factors are:
3400 acfm = 1 MWe
360 acfm - 106 Btu/hr
- 559-111/20615
92
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