i y ' j-- , -, , ,
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EPA 440/1-76/084 |\ D A CT
Supplement For
PRETREATMENT
to the
Development Document
for the
STEAM ELECTRIC
POWER GENERATING
Point Source Category
ro
U.S. ENVIRONMENTAL PROTECTION AGENCY
NOVEMBER 1976
-------
SUPPLEMENT FOR PRETREATMENT
TO THE DEVELOPMENT DOCUMENT
FOR THE
STEAM ELECTRIC POWER GENERATING
POINT SOURCE CATEGORY
Russell E. Train
Administrator
Andrew W. Breidenbach, Ph.D.
Assistant Administrator
for Water and Hazardous Materials
Eckardt C. Beck
Deputy Assistant Administrator for
Water Planning and Standards
Robert B. Schaffer
Director, Effluent Guidelines Division
John Lum
Project Officer
NOVEMBER 1976
Effluent Guidelines Division
Office of Water and Hazardous Materials
U.S. Environmental Protection Agency
Washington, D.C. 20460
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ABSTRACT
This document presents the findings to date of an extensive
study of that section of the Steam Electric Power Generating
Industry which discharges industrial wastes to publicly
owned treatment works (POTW). Its purpose is to develop
pretreatment standards to implement section 307(b) of the
Federal Water Pollution Control Act.
Pretreatment standards, recommended in Section II of this
report set forth the degree of effluent reduction achievable
through the application of control technology currently
available. These pretreatment standards set forth the
degree of effluent reduction achievable through application
of the available demonstrated control t'echnology, processes,
operating methods, or other alternatives. These standards
must be achieved no later than three (3) years from the
date of promulgation.
Supporting data and rationale for development of pretreat-
ment standards are contained in this report.
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TABLE OF CONTENTS
ABSTRACT
NOTICE
TABLE OF CONTENTS
LIST OF FIGURES
LIST OF TABLES
I.
II.
Ill
IV
CONCLUSIONS
RECOMMENDATIONS
INTRODUCTION
General Background
Purpose and Authority
Scope of Work and Technical Approach
General Description of the Industry
Process Description
Publicly-Owned Treatment Works (POTW)
INDUSTRY CATEGORIZATION
Introduction
Industry Categorization
Factors Considered
Age
Size
Fuel
Geography
Mode of Operation
Raw Water Quality
Volume of Water Used
Pretreatment Technology
Paqe
^^
iii
vi-i
ix
1-1
II-l
III-l
III-l
III-2
III-2
III-6
111-13
111-15
IV-1
IV-1
IV-1
IV-2
IV-2
IV-2
IV-2
IV-2
IV-3
IV-3
IV-3
IV-3
^^^
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TABLE OF CONTENTS (CONTINUED)
Page
V. WATER USE AND WASTE CHARACTERIZATION V-l
Introduction V-l
Principles of Operation of Steam Electric
Power Plant V-l
Water Use and Waste Characterization by
Category V-6
Condenser Cooling Water V-6
Water Treatment V-23
Demineralizer V-30
Boiler Slowdown V-36
Maintenance Cleaning V-42
Ash Handling Systems V-46
Air Pollution Control Equipment V-55
The POTW Process V-60
Effects of Steam-Electric Wastewaters
On POTWs V-67
VI. SELECTION OF POLLUTANT PARAMETERS VI-1
Introduction VI-1
Rationale for the Selection of VI-1
Pollutant Parameters
Properties of Selected Pollutant
Parameters VI-2
Pollutants Rejected VI-17
^v
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TABLE OF CONTENTS (CONTINUED)
Page
VII. TREATMENT AND CONTROL TECHNOLOGY VII-1
Introduction .... 1
End-of-Pipe Treatment Technology VII-2
Treatment of Major Pollutants VII-2
End-of-Pipe Technology for Major
Waste Streams VII-8
Water Management VII-14
In-Plant Control Techniques VII-15
Material Substitution VII-19
Water Conservation and Wastewater Reuse VII-21
VIII. COST, ENERGY AND OTHER NON WATER QUALITY
ASPECTS VIII-1
Introduction VI_- .
Cost Reference and Rationale VIII-2
Costs for Pretreatment VIII-5
Levels of Pretreatment VIII-15
Cost Estimates VIII-19
Ultimate Disposal VIII-28
Energy Considerations VIII-30
IX. PRETREATMENT STANDARDS IX-1
X. ACKNOWLEDGEMENTS X-l
XI REFERENCES XI.-,
XII GLOSSARY XII-1
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TABLE OF CONTENTS (CONTINUED)
Page
APPENDIX A - STATISTICAL ANALYSIS OF HISTORICAL A-l
DATA
APPENDIX B - WATER GLOSSARY B-l
APPENDIX C - EFFECT OF POLLUTANT PARAMETERS ON
TREATMENT WORKS C-l
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LIST OF FIGURES
Page
III-l Principal Fuel Use by Number III-9
III-2 Principal Fuel Use by Megawatts 111-10
III-3 Year of Construction by Number III-ll
III-4 Year of Construction by Megawatt 111-12
III-5 Process Flow Diagram Steam Electric
Power Industry 111-14
III-6 Wastewater Treatment Sequence 111-16
V-l Typical Boiler for Oil-Fired Furnace V-3
V - 2 Single-passCondenser V- 5
V-3 Fossi1-Fueled Steam Electric Power
Plant - Typical Flow Diagram V-7
V-4 Once-Through and Recirculating
Cooling Systems V-10
V-5 Diagram of Wet Forced - Air Cooling
Tower V-l 1
V-6 Natural Draft Wet Cooling Tower
(Counter Flow) V-12
V-7 Normal Distribution Diagram For
Normalized Once-Through Usage Data V-14
V-8 Once-Through Cooling Water Use vs.
Annual Production Rate V-16
V-9 Normal Distribution Diagram for
Normalized Cooling Water Usage Data V-18
V-10 Recirculating Cooling Water Use vs.
Annual Production Rate V-20
V-ll Commonly Used Water Treatment Methods V-25&26
v^^
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LIST OF FIGURES (CONTINUED)
Page
V-12 Normal Distribution Diagram for
Normalized Boiler Makeup Water Usage V-28
Data
V-13 Boiler Makeup Water Use vs. Annual
Production Rate V-31
V-14 Normal Distribution Diagram for
Normalized Ion Exchange Water Usage V-33
Data
V-15 Demineralizer Water Usage vs. Annual
Production Rate V-35
V-16 Flow Diagram for Recirculating Bottom
Ash System V-47
V-17 Flow Diagram for Air Pollution Control
Scrubbing System V-56
V-18 Flow Diagram of Secondary Treatment
Methods V-63
V-19 Wastewater Treatment Flow Diagram V-65
V-20 Flow Diagram for Sludge Treatment V-66
V-21 Flow Diagram of Nitrification -
Denitrification Process V-68
VIII-1 Model Waste Pretreatment Plant - 25 MW
Generating Facility VIII-17
VIII-2 Model Waste Pretreatment Plant - 500 MW
Generating Facility VIII-18
VIII-3 Cooling Water System Slowdown Treatment VIII-26
•0111
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LIST OF TABLES
Page
III-l Total Steam Electric Plants
in the Contiguous United States III-7
III-2 Steam Electric Plants Discharging
to Municipal Sewers in the Contiguous
United States III-8
V-i Statistical Parameters For the Three .
Modes of Normal Distribution - Once-
Through Condenser Cooling
V-2 Statistical Parmeters For the Three
Modes of Normal Distribution -
Recirculating Condenser Cooling V-19
V-3 Raw Water Flows and Loadings -
Condenser Cooling Systems V-22
V-4 Statistical Parmeters for the Three
Modes of Normal Distribution - Boiler
Makeup V-29
V-5 Statistical Parmeters for the Three
Modes of Normal Distribution - Boiler
Demineralizer V-34
V-6 Raw Waste Flows and Loadings - Water
Treatment V-37&38
V-7 Effluent Flows and Loadings - Water
Treatment V-39
V-8 Raw Waste Flows and Loadings - Boiler
Slowdown V-41
V-9 Raw Waste Flows and Loadings -
Maintenance Cleaning V-44
V-10 Ash Disposal Methods V-48
V-11 Raw Waste Flows and Loadings — Ash V-51
Handling
V-12 Effluent Flows and Loadings - Ash
Handling V-52
^x
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LIST OF TABLES (CONTINUED)
Page
V-13 Power Plant and POTW Flows V-69
V-14 Raw Waste Flows and Loadings - Combined
Discharge to POTW V-71
VII-1 End-of-Pipe Treatment Methods VII-3
VII-2 Solid/Liquid Separation Systems VII-4
VII-3 Treatment of Major Pollutants VII-5
VII-4 Typical Composition of Boiler Chemical
Cleaning Wastes VII-12
VII-5 Typical Composition of Boiler Fireside
Wash Wastes VII-12
VII-6 Recovery Processes for Flue Gas
Desulfurization Systems VII-20
VIII-1 Wastewater Treatment Costs and Resulting
Waste-load Characteristics for Typical
Plant VIII-7
VIII-2 Wastewater Treatment Costs and Resulting
Waste-load Characteristics for Typical
Plant VIII-8
VIII-3 Summary of Capital Costs Oil and Gas
Fired Plants - 25 MW Plant VIII-10
VIII-4 Wastewater Treatment Cost and Resulting
Waste-load Characteristics for Typical
Plant VIII-13
VIII-5 Wastewater Treatment Costs and Resulting
Waste-load Characteristics for Typical
Pl-ant VIII-14
VIII-6 Summary of Capital Costs Coal Fired
Plant VIII-15
VIII-7 Estimated Capital Costs - Chemical
Wastes Pretreatment Plant VIII-20
VIII-8 Assumed Unit Costs VIII-21
x
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LIST OF TABLES (CONTINUED)
Page
VIII-9 Operating Costs - Pretreatment of Low
Volume and Metal Cleaning Wastes VIII-^
VIII-10 Estimated Capital Cost - Cooling Water
System Slowdown Treatment VIll-^/
VIII-11 Estimated Operating Costs-Cooling
Water System Slowdown Treatment VIII-27
XI
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DRAFT
SECTION I
CONCLUSIONS
An engineering evaluation of steam electric power generating
plants that discharge all or a portion of their aqueous
wastes vto publicly-owned treatment works (POTW's) was
conducted to establish the basis for pretreatment standards.
For the purpose of establishing such standards it was
deemed practical to subcategorize the industry into the
following waste-type subcategories:
Condenser Cooling System
Boiler Water Pretreatment
Boiler Slowdown
Maintenance Cleaning
Ash Handling
Drainage
Air Pollution Control Devices
Miscellaneous Waste Streams
This subcategorization is identical to that presented in the
development document for direct dischargers (14) in this
Industry with the deletion of Construction Activity and
Low Level Radwastes. This subcategorization was found to
be valid as examination of process characteristics, raw
wastes and treated wastes were not found to be significantly
different from those of direct dischargers.
Conduct of the work involved contact with 49 steam electric
power generating stations, representing 50 percent of the
estimated 98 stations discharging chemicals wastes to a
POTW. Engineering visits and data collection were made to
22 stations. Sampling of raw and pretreated wastes was obtained
from eight (8) stations. Additionally, prior work conducted by
the EPA, data collected in response to NPDES and local
discharge permit monitoring, industrial effluent data, and
relevant literature prepared by the EPA and electrical trade
journals were evaluated.
1-1
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DRAFT
Based on the above evaluation, the following conclusions
were reached:
t There exists no significant difference between
processes and corresponding effluents of the
population of plants discharging to the POTW
and those of direct dischargers.
• The subcategorization developed above is valid
for the purpose of establishing pretreatment
standards.
• Stations discharging to the POTW are capable
of pretreating effluents to the degree
of effluent removal attainable by application
of the best practicable control technology
currently available (BPCTCA) for direct
dischargers.
A survey of current industry practices has indicated that
most plants provide little pretreatment of chemical type
wastes at the present time.
1-2
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DRAFT
SECTION II
RECOMMENDATIONS
The EPA will propose standards after review and
evaluation of the information included in this document
II-l
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DRAFT
SECTION III
INTRODUCTION
GENERAL BACKGROUND
The involvement of the Federal Government in water pollution
control dates back to 1948 when Congress enacted the first
comprehensive measure aimed specifically at this problem.
At that time the Surgeon General, through the U.S. Public
Health Service, was authorized to assist states in various
ways to address the problem. The emergence of a national
water pollution control program came about with the
enactment of the Water Pollution Control Act of 1956 (Public
Law 84-660). To date this law remains the basic law
governing water pollution. It establishes the basic system
of technical and financial assistance to states and
municipalities, as well as enforcement procedures by which
legal steps can be initiated against polluters.
The present program dates back to the Water Quality Act of
1965 and the Clean Water Restoration Act of 1966. Under the
1965 Act, states were required to adopt water quality
standards for interstate waters, and to submit to the
Federal Government, for approval, plans to implement and
enforce these standards. The 1966 Act authorized Federal
participation in construction of sewage treatment plants.
On amendment, the Water Quality Act of 1970, extended
Federal activities into such areas as pollution by oil,
hazardous substances, sewage from vessels, and mine drainage.
Originally, pollution control activities were the
responsibility of the U.S. Public Health Service. In 1961,
the Federal Water Pollution Control Administration (FWPCA)
was created in the Department of Health, Education and
Welfare, and in 1966, the FWPCA was transferred to the
Department of the Interior. The name was changed in early
1970 to the Federal Water Quality Administration and in
December 1970, the Environmental Protection Agency (EPA) was
created by Executive Order as an independent agency outside
the Department of the Interior. Executive Order 11574 on
December 23, 1970, established the Permit Program, requiring
all industries to obtain permits for discharge of wastes
into navigable waters or their tributaries under the
provisions of the 1899 River and Harbor Act (Refuse Act).
The permit program immediately became involved in legal
problems resulting in a court ruling that effectively
stopped issuance of a significant number of permits. It did
result in the filing with EPA, through the U.S. Army Corps
of Engineers, of applications for permits which, represent a
III-l
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DRAFT
complete inventory of industrial waste discharges. The
granting of a permit under the Refuse Act was dependent on
the discharge being able to meet applicable water quality
standards. Although EPA could not specify methods of
treatment, they could require minimum effluent levels
necessary to meet water quality standards.
The Federal Water Pollution Control Act Amendments of 1972
(the "Act") made a number of fundamental changes in the
approach to achieving clean water. One of the most
significant changes was from a reliance on water quality
related effluent limitations to a direct control of effluents
through the establishment of technology-based effluent
guidelines to form an additional basis, as a minimum, for
issuance of discharge permits. The permit program under the
1899 Refuse Act was placed under full control of EPA, with
much of the responsibility to be delegated to the States.
PURPOSi^ AND AUTHORITY
Under the Act, the Environmental Protection Agency is
charged with establishing pretreatment standards to protect
the operation of publicly-owned treatment works and to
prevent discharge of pollutants which pass through such
works inadequately treated.
As part of this Act, Section 307(b) states that the
Administrator shall "publish proposed regulations establishing
pretreatment standards for introduction of pollutants into
treatment works (as defined in Section 212 of this act)
which are publicly owned for those pollutants which are
determined not to be susceptible to treatment by such
treatment works or which would interfere with the operation
of such treatment works. Pretreatment standards under this
section shall specify a time for compliance not to exceed
three years from the date of promulgation."
This report is prepared for the purpose of developing
pretreatment standards for existing sources. Pretreatment
Standards for new sources are required under Section 307(c)
of the Act have been promugated October of 1974, (together
with the effluent guidelines for the Steam Electric Power
Plant Source Category).
SCOPE 0£ WORK AND TECHNICAL APPROACH
The pretreatment standards proposed herein were developed in
the following manner. The list of plants that discharge to
a POTW was first studied for the purpose of determining
whether separate standards would be required for different
divisions within the list. The analysis was based upon fuels
used, production process empl oyed,' wastewater pretreatment
at plant sites, process employed by the POTW receiving plant
wastewater, and other factors. The raw waste characteristics
for each subcategory were then identified. This included an
analyses of (1) the source and volume of water used in the
III-2
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DRAFT
process employed and (2) the constituents (including thermal)
of all wastewaters including constituents which result in
taste, odor, and color in water. The constituents of
wastewaters which should be subject to pretreatment standards
were identified.
The full range of control and pretreatment technologies
existing within each subcategory was identified. This
included identification of each distinct control and
pretreatment technology, including both in-plant and
end-of-process technologies, which are existent or capable
of being designed for each subcategory. It also included an
identification of the amount of constituents and the chemical,
physical, and biological characteristics of pollutants.
Effluent levels resulting from the application of each of
the pretreatment and control technologies were also
Identified. The problems, limitations, and reliability of
each pretreatment and control technology were also identified.
In addition, the nonwater quality environmental impact, such
as the effects of the application of such technologies upon
other pollution problems, including air, and solid waste,
were also identified. The energy requirements of each of
the control and treatment technologies were identified as
well as the cost of the application of such technologies.
The information, as outlined above, was then evaluated in
order to determine what levels of technology are available
for effluent reduction. In identifying such technologies,
various factors were then considered. These included the
total cost of application of technology in relation to
effluent reduction benefits to be achieved from such
application, the age of equipment and facilities involved,
the process employed, the engineering aspects of the
application of various types of control techniques, process
changes, nonwater quality environmental impact (including
energy requirements), and other factors.
Data for identification and analyses were obtained from a
number of sources. These sources included EPA research
information; EPA, state, and local environmental personnel;
trade associations; published literature; qualified technical
consultation; historical information on effluent quality and
quantity; and on-site visits including analytical programs
and interviews at steam electric plants throughout the
United States which were known to have above average waste
pretreatment facilities. All references used in developing
the pretreatment standards reported herein are listed in
Section XI of this document.
III-3
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DRAFT
Twenty-two operating plants were visited and eight were
sampled. Composite samples over a sixteen hour period were
obtained from these eight plants and were analyzed for
parameters mentioned in Section V. Information was obtained
from as many as fifteen (15) plants for each waste-type
subcategory. Both in-process and end-of-pipe data were
obtained as a basis for determining water use rates
capabilities and effluent loads. Permit application data
was of value for the purposes of this study when such data
covered outfalls serving only s'jteam electric power operations
Cost information was obtained directly from industry during
plant visits, from engineering firms, equipment suppliers,
and from the literature. These costs have been used to
develop general capital, operating, and total costs for each
pretreatment and control method. This generalized cost data
and specific information obtained from plant visits was used
to estimate cost effectiveness in Section VIII and elsewhere
in this report.
Certain plants were selected for in-depth analysis from the
total population of those visited. These plants were
plants discharging representative waste types or exhibiting
superior performance in pollutant discharge or having
substantial quantities of historic effluent data.
The following selection criteria were developed and used for
selection of plants to be included in this study.
t Discharge ojf representative wastes types
Plants that discharge types or quantities
of waste representative of those delineated in
Section IV.
• Hater management practices
Plants that had good management practices
such as good process and quality control,
good maintenance, water reuse, conservation, and
in-plant water segregation.
• Al'r pol lution and solid waste control
Plants that had overall effective air and solid
waste pollution control, in addition to
III-4
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DRAFT
water pollution control technology. Care was
taken to insure that all plants chosen have
minimal discharge to the POTW and that
sites are not those which exchange one
form of pollution for another.
Eff1uent pretreatment methods and their
effecti veness
Plants were those using technology
approaching BPCTCA, operating controls, and
operational reliability. Pretreatment methods
considered included such process modifications
as may significantly reduce effluent loads, as
well as conventional pretreatment processes.
Plant faci1ities
Plants that had all the facilities
normally associated with the generation of
electric power from steam. Typical facilities
generally were plants which have all normal process
steps carried out on-site.
Plant management philosophy
Plants whose management insists
upon effective equipment maintenance, good
housekeeping practices, and efficient land use.
Geographi c location
Factors such as land availability, rainfall, feed
water quality, and differences in state and local
standards were also considered.
Characteristi cs ojf publ i cly-owned treatment works
receiving power pi ant di scharges
Size, process employed, pollutants not susceptible
to treatment, and any pollutants which would
interfere with normal operation at a POTW were
taken into consideration.
III-5
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DRAFT
GENERAL DESCRIPTION 0£ THE INDUSTRY
The Steam Electric Power Industry is made up of 1273 plants
throughout the contiguous United States. Of these plants an
estimated 7.7 percent or 98 plants discharge wastewaters to
publicly-owned treatment works and are thus covered by the
scope of this document. In this study 49 plants discharging
to POTW's were contacted.
Statistics for this section were estimated based on a truly
random sampling of steam electric power plants contained in
the "Environmental Assessment of Alternative Thermal Control
Strategies for the Electric Power Industry" by Michelle M.
Zarubica of the Office of Planning and Evaluation of the
Environmental Protection Agency (18).
Steam Electric plants discharging to the POTW tended to be
smaller on the average than plants discharging to surface
water. These plants averaged about 150 MW for a total
capacity of 14,500 MW which compares with an average capacity
and total generating capacity of about 400 MW and 506,700 MW
for the entire Steam Electric Industry. (See Tables III-l
and III-2). Of these plants, an estimated 72 percent are
publicly-owned and 28 percent are investor owned.
Most of the Steam Electric plants that discharge to POTW's
(68 percent) use gas as their principal fuel compared to 31
percent for the entire industry Figures III-l and III-2.
Conversion of some plants from gas to oil is expected due to
shortage of natural gas.
Plants which discharge wastewaters to POTW's tend to be
older than plants which discharge to surface waters. Tables
III-l and III-2 show that 29 percent of the plants which
discharge to POTW's were built since 1960 as compared to 38
percent for the entire population. Also, plants built since
1960 represent 48 percent of the generating capacity of
plants discharging to POTW's compared to 78 percent for the
entire Steam Electric Industry. (See Figures III-3 and III-
4).
Approximately 24 percent of all electrical generation is
nuclear powered but no plants of this type were observed to
discharge to the POTW. Nonetheless, nuclear plants are
included in this document, since their chemical waste
discharges are similar in nature to those discharged by non-
nuclear facilities (14).
Steam Electric plants discharging to POTW's are located in
all regions of the country with somewhat higher than average
concentrations in the Midwest and in California.
III-6
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DRAFT
Table III-l. Total Steam Electric Plants in the
Contiguous United States
Total Number of Plants = 1273
Total Number of Units = 3011
Total Number of Megawatts= 506,654
Average Station Size = 398
Percentage of Plants Confirmed as Discharging
to Municipal Sewers - by Number =7.7%
by Megawatts = 2.9%
Principal Percentage by Percentage by
Unit Fuel Number Megawatts
Gas 31.0 12.6
Oil 14.6 14.0
Coal 49.3 49.6
Nuclear 5.1 23.8
100.0 100.0
Percentage by Percentage by
Unit Built In Number Megawatts
1970's 17.6 57.6
1960's 20.3 20.1
1950's 36.1 17.6
1940's 16.0 3.7
1930's 6.5 0.8
1920's 2.7 0.1
1910's 0.8 0.1
III-7
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DRAFT
Table III-2. Steam Electric Plants Discharging to
Municipal Sewers in the Contiguous United States
Total Number of Plants = 98
Total Number of Units = 277
Total Number of Megawatts = 14504
Average Station Size = 148
Principal
Unit Fuel
Gas
Oil
Coal
Nuclear
Percentage by
Number
67.7
17.7
14.7
0.0
100.0
Percentage by
Megawatts
44.1
54.0
1.9
0.0
100.0
Unit Built In
1970'
I9601
1950'
1940'
1930'
1920'
1910'
Percentage by
Number
5.9
23.5
35.3
23.5
5.9
5.9
0.0
100.0
Percentage by
Megawatts
III-8
-------
PERCENTAGE OF PLANTS
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-------
DRAFT
100 ,.
90
80
<£.
CD
UJ
70
60
OVERALL PLANTS
POPULATION DISCHARGING
TO POTW'S
UJ
LU
D-
50
40
30 ..
20
10 . ,
GAS
Figure III-2
OIL
PRINCIPAL FUEL
COAL
NUCLEAR
Principal Fuel Use by Megawatts
111-10
-------
DRAFT
100
90
80
70
UJ
QO
UJ
o
or
60
50
40
OVERALL DISCHARGING
POPULATION TO POTW'S
30
20
10 .
n
1910
1920 1930 1940 1950 1960
YEAR PLANT BUILT
1970
Figure III-3. Year of Construction by Number
III-ll
-------
DRAFT
100
90
80
CO
I—
£ 70
3
CD
OVERALL PLANTS
POPULATION DISCHARGING
TO POTW'S
o 60
UJ
CD
o
UJ
D_
50
40
30
20
10
n
+
1960 1970
1910
1920
1930 1940 1950
YEAR PLANT BUILT
Figure III-4.
Year of Construction by Megawatt
111-12
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DRAFT
Process Description
The "production" of electrical energy
and conversion of chemical or nuclear
methods of utilizing energy of fossil
combustion process, followed by steam
the heat first into mechanical energy
the mechanical energy into electrical
theoretical efficiency that can be obtained
heat to work is limited by the temperatures
involves utilization
energy. Present day
fuels are based on a
generation to convert
and then to convert
energy. The maximum
in converting
at which the
heat can be absorbed by the steam and discarded to the
environment. The upper temperature is limited by the
temperature of the fuel bed and the structural strength and
other aspects of the boiler. The lower temperature is
ideally the ambient temperature of the environment, although
for practical purposes the reject temperature must be set by
design significantly above the highest anticipated ambient
temperature. Within these temperatures, efficiencies are
limited to about 40 percent regardless of any improvement to
the machines employed. For any steam electric power
generation scheme, therefore, a minimum of 60 percent of
the energy contained in the fuel must be rejected to the
environment as waste heat (14).
Fossil-fueled steam electric power plants produce electric
energy in a four-stage process, shown in Figure III-5. The
first operation consists of the burning of the fuel in a
boiler and the conversion of water into steam by the heat of
combustion. The second operation consists of the conversion
of the high-temperature, high-pressure steam into mechanical
energy in a steam turbine. The steam leaving the turbine is
condensed to water, transferring heat to the cooling medium,
which is normally water. The turbine output is conveyed
mechanically to a generator, which converts the mechanical
energy into electrical energy. The condensed steam is
reintroduced into the boiler to complete the cycle.
The theoretical water-steam cycle employed in steam electric
power plants is known as the Rankine cycle. Actual cycles
in power plants only approach the performance of the Rankine
cycle because of practical considerations. Thus, the heat
absorption does not occur at a constant temperature, but
consists of heating of the liquid to the boiling point,
converting the liquid to vapor and superheating (heating
above the saturation equilibrium temperature) the steam.
Superheating is necessary to prevent excess condensation in
the turbines and results in an increase in cycyle efficienty.
Reheating, the raising of the temperature above saturation of
the partially expanded steam, is used to obtain improvements in
efficiency and again to prevent excess condensation. Preheating
111-13
-------
Fuel Inlet
Boiler
Ash Outlet
Steam
Boiler Feed Water
Condenser
Generator
Electric
»-
Power
Cooling Water In
Cooling Water Out
FIGURE III-5
Process now Diagram
Steam Electric Power Industry
-------
DRAFT
of condensate to near temperatures with waste heat, is also
used for this purpose. Condensers cannot be designed to
operate at theoretically optimum values because it would
require infinitely larger equipment. All of these divergences
from the optimum theoretical conditions cause a decrease in
efficiency and an increase in the amount of heat rejected
per unit of production. As a result, only a few of the
larger and newer plants approach even the efficiencies possible
under the ideal Rankine cycle. Also, as a result of second
law limitations, modifications of the steam cycle of an
existing plant are not likely to result in significant
reductions in heat rejection.
Pub! idy-Owned Treatment Works (PQTW)
The POTW process is broken down into three basic treatment
methods; primary, secondary, and tertiary. Primary treatment
consists of the removal of coarse materials, settleable
solids, oil and grease, floating material, and the
reduction of biological oxygen demand. Most POTW's employ
secondary treatment which converts soluble and colloidal
organic material into settleable flocculant material that
can be removed by sedimentation. Secondary treatment is
often enhanced by the addition of chemicals such as iron,
aluminum salts, and polymeric flocculants. The use of tertiary
treatment processes are still uncommon and include the
removal of chemical constituents not affected by primary and
secondary treatment. Tertiary treatment is intended to
remove chemicals which promote algae growth and unwanted
aquatic vegetation.
The POTW's receiving wastewaters
from Steam Electric plants
vary in size and treatment process employed. Plant size is
determined by human population and industrial waste load of
the area served. Those contacted in this study ranged from
200,000 gpd to 350,000,000 gpd in size. Treatment methods
are determined by flow, waste load pollutant constituents,
economics, energy and removal requirements, and plant age.
There are a large number of wastewater treatment processes
in use whose application is related both to the characteristics
of the waste and the degree of treatment required. These
processes are shown in Figure III-6.
111-15
-------
PRIMARY
TREATMENT
SECONDARY
TREATMENT
TERTIARY
TREATMENT
fin Hntanur.._
I
CTi
Figure III-6. Wastewater Treatment Sequence
-------
DRAFT
SECTION IV
INDUSTRY CATEGORIZATION
INTRODUCTION
An evaluation of steam e
discharging chemical was
works (POTW's) was neces
categorization and subca
preparation of effluent
industry. From this eva
stations discharging to
according to individual
Subcategorization was ba
groups of plants.
lectric power industry stations
tes to publicly-owned treatment
sary to determine whether
tegorization would be helpful in the
pretreatment standards for this
luation, steam electric industry
POTW's have been categorized
industrial waste sources.
sed on distinguishing factors within
This method of categorization was also used and is discussed
in detail in the "Development Document for Effluent
Limitation Guidelines and New Source Performance Standards
for the Steam Electric Power Generating Category" October
1974 (18). In this study on pretreatment, however, low level
radioactive wastes are not addressed.
The basis of evaluation of plants in the industry will be a
combination of the appropriate waste sources for a particular
power plant. Guidelines will be established for each waste
source and can then be applied and utilized in the manner of
a building block concept. In the case of combined waste
streams the appropriate guidelines will be combined and
weighted proportional to stream flow. The eight categories
are presented in Table IV-1.
The following were considered for industry categorization:
age, size, fuel, geography, mode of operation, raw water
quality, volume of water used, and pretreatment technology.
INDUSTRY CATEGORIZATION
This industry
industrial was
in fuel type,
streams. Thes
Although age,
water hardness
not appear to
analyses discu
Sections V and
has been categorized according to the individual
te source. Marked differences were observed
boiler, pretreatment, and maintenance waste
e differences were the basis for subcategorization
size, geography, mode of operation, and feed
did vary greatly, these characteristics do
directly affect discharges. Statistical
ssed in Section III and information found in
VII were utilized in reaching these conclusions.
IV-1
-------
DRAFT
TABLE IV-1
I. Condenser Cooling System
A. Once-Through
B. Recirculating
II. Boiler Water Pretreatment
A. Clarification
B. Softening
C. Ion Exchange
D. Evaporator
E. Filtration
F. Other Treatment
III. Boiler or PWR Steam Generator
A. Slowdown
IV. Maintenance Cleaning
A. Boiler or PWR Steam Generator Tubes
B. Boi1er Fi reside
C. Air Preheater
D. Misc. Small Equipment
E. Stack
F. Cooling Tower Basin
V. Ash Handling
A. Oil-Fired Plants
1. fly ash
2. bottom ash
B. Coal-Fired Plants
1. fly ash
2. bottom ash
VI. Drainage
A. Coal Pile
B. Contaminated Floor and Yard Drains
VII. Air Pollution Control Devices
A. 502^ Removal
VIII. Miscellaneous Waste Streams
A. Sanitary Wastes
B. Plant Laboratory and Sampling Systems
C. Intake Screen Backwash
D. Closed Cooling Water Systems
IV-2
-------
DRAFT
FACTORS CONSIDERED
Age
Power plants discharging to the POTW's tend to be older than
surface water discharging plants. In steam electric power
plants, individual generation units are often installed at
different times over a number of years. Newer units tend
to be thermally more efficient then older plants and use
less fuel per killowatt hour of electricity produced.
Because of fuel economics newer units generally tend to be
used for base load production while other units are employed
as peaking and cyclic units. Increased fuel efficiency may
reduce wastewater loads such as ash transport water,
wet scrubber water, etc. However, since age of units varies
within even a single plant and no correlation can be drawn
between processes, types of waste discharge, and plant age,
age is not regarded as a suitable basis for categorization.
Size
Although the size of steam electric power plants discharging
to POTW's various significantly, the basic process is common
to all facilities. Plant size was found to have little
affect on quantity of treated effluent. Plants discharging
to sanitary sewers tend to be smaller than power plants
discharging to surface water. Therefore, size is rejected
as criteria for categorization.
Fuel
Plants discharging to POTW's were identified as burning all
three major fossil fuels, coal, oil, and gas. In contrast to
the entire population of steam electric plants in the U.S.
the majority of plants contacted in this study use gas as
fuel. Fuel-related wastes such as ash control transport
water and coal pile drainage, can contribute to wastewater
discharge. The presence of sulfur in the fuel may require
scrubbers. Therefore, the affect of different fuels on certain
processes and effluents is useful for subcategorization.
Geography
Usually, steam power plants that discharge to the POTW's are
located near or within municipal boundaries. Most of the
plants contacted were, in fact, situated in downtown areas.
Plants discharging to the sewers were located in nearly all
geographical regions of the United States. It is noted that
recent trends toward larger power generating stations, and
the institution of mine-mouth coal fed plants, have resulted
in increased rural plant construction and a reduced
number of municipally-located plants.
IV-3
-------
DRAFT
Since plant processes do not vary according to geography,
all plants covered in this study are located in or near
municipalities, geography is rejected as a criteria for
categorization.
Mode erf Operation
Despite the fact that peaking and cyclic stations are older
and smaller than base load stations, many units of plants
are often utilized for extended periods for either purpose.
Additionally, the basic operation is independent of the
type of service provided. Therefore, mode of operation is
rejected as a criteria for categorization.
Raw Water Qua!ity
After study of the affects of raw water quality on effluent
discharge, quality of raw water was determined not to be a
criteria for categorization. Hardness would indeed affect
operation by increasing the frequency of regeneration of the
deionizer or recharging the softener. The harder the raw
water the more frequently the deionizer anion and cation must
be regenerated and the hot lime and zeolite units have to be
recharged. Effects of raw water quality are included in the
Boiler Water Pretreatment Category.
Volume of Hater Used
Water use varies greatly even among plants of approximately
the same size. It depends primarily on the type of cooling
system, the cost and quality of the water supply, and the
extent to which water conservation is practiced by individual
plants. Because of wide variations in water consumption
among individual plants of this industry, water use was not
found to be acceptable criterion for categorization.
Pretreatment Technology
A wastewater treatment system should be an integral part of
a plant's water management program. It should be designed
on the basis of the quality and quantity of the wastewater
to be treated and its ultimate disposal. Many plants in the
industry discharge their wastewater effluent to municipal
sewer systems; others discharge only a portion. The extent
of pretreatment varies widely from no pretreatment to
integrated plants using complex systems such as equalization,
neutralization, etc.
No pattern was found for pretreatment technology in the
industry, thus it is not a suitable basis for categorization.
IV-4
-------
DRAFT
SECTION V
WATER USE AND WASTE CHARACTERIZATION
INTRODUCTION
Specific water uses and the waterborne wastes involved in
steam electric plants discharging into publicly-owned treatment
works (POTW) are described in this section, along with other
process waste materials. Process waters are characterized
as raw waste loads from specific processes associated with
the production of electricity. These are generallly
expressed as grams per megawatt hour (MWH) of electricity
generated. Water uses are given in terms of liters per
per day and waterborne waste loads in
per MWH. The waste treatments used by
and POTWs are described, and amounts and
waste effluents after treatment are
MWH, or as liters
mg/liter or grams
both power plants
types of waterborne
characterized.
PRINCIPLES 0£ OPERATION Of STEAM ELECTRIC POWER PLANT
In a steam electric power plant, thermal energy, produced
by rapid chemical combustion or nuclear fission reaction,
is first tranformed into high pressure, high temperature
steam, and then to mechanical energy through expansion of
the steam in a turbine. The process can be divided into
four stages. The first operation consists of fuel
combustion in the boiler furnace to produce high pressure,
superheated steam. The steam is conveyed to a turbine
where it is allowed to gradually expand and cool in the
various turbine stages to convert the thermal energy into
electrical energy via mechanical energy. In the third
operation the steam exiting from the final stage of the
turbine is condensed to water, transferring the heat to a
cooling medium, which is normally water. Finally the
condensed steam is re introduced into a boiler by a pump
to complete the cycle.
The power
principal
cycl e
units:
components can be divided into three
steam boiler
steam turbine
condenser
V-l
-------
DRAFT
Each of the cycle components provides an energy transfer
and transformation function necessary to convert the heat
energy into useful work. The following are descriptions of
these three units. A more extensive discussion on the
principles of design and operation of steam electric power
plants can be found elsewhere (14,16).
Boilers
All boilers use the same basic design, that is, they are
large multi-tube heat exchangers surrounded by a furnace.
The feedwater circulates within the tubes where it is heated,
vaporized, and superheated producing steam to drive the
steam turbine generators. Many different boiler
arrangements are used. Oil and gas-fired boilers are simpler
than coal-fired boilers because liquid and gaseous fuels do
not require the conveyers, pulverizers, and ash collection
equipment necessary in coal-fired boilers. The boiler
structure may be either exposed or enclosed depending on
local weather conditions, and is usually very large to
accommodate the large tube surface areas required. Air
heaters, economizers, and other sections of the boiler
are used to extract the maximum amount of heat from the
combustion gases before they are discharged to the
environment. This serves to increase the boi1ers_efficiency:
the ratio of heat converted to steam to the heat input
value of the burning fuels. Modern power boilers are able
to achieve 85 to 90 percent efficiencies; the remaining
10 to 15 percent of the input heat value is discharged to
the environment with the exhaust gases. This loss is
referred to as the "stack loss." Figure V-l shows a typical
boiler for an oil-fired furnace.
Steam Turbine
The steam turbine consists of alternate rows of nozzles and
blades on wheels. Each row of nozzles and its associated
row of blades is called a turbine stage. As the steam
expands through the nozzles, the pressure decreases and
the velocity and specific volume increase. When the steam
comes in contact with the blades a part of the momentum
(kinetic energy) is transferred to the blades. The turbine
shaft and generator are caused to rotate and electricity
is produced.
V-2
-------
DRAFT
FIGURE V-l. Typical Boiler For Oil-Fired Furnace
V-3
-------
DRAFT
There are many different types of turbines and turbine
arrangements in use. Most of the turbines are of the
condensing type, discharging the steam from the last stage
at below atmospheric pressure. The efficiency of a
turbine is highly sensitive to the exhaust pressure (back
pressure). Turbines designed for once-through cooling
systems are generally operated at lower back pressures than
that designed for closed cooling systems.
In most turbine arrangements a portion of the steam leaves
the casing before the final stage. This type of turbine
is referred to as extraction turbine. The extracted steam
is used for feedwater heating purposes. In some turbines,
a portion of the steam is extracted from intermediate stages,
reheated in the boiler, and returned to the turbine or another
turbine as a means of improving overall efficiency.
Steam Condensation
Steam leaving the final stage of the turbine is condensed
into water in the condenser. This is essentially a very
large shell and tube heat exchanger designed to withstand
the high vacuums associated with modern steam turbine
power cycles. Heat is transferred from the exhaust steam to
an external cooling water system which may draw water from
a surface or underground source, or from the cooling tower.
There are two types of condensers; the single-pass and the
two-pass condensers. If all the water flows through the
condenser tubes in one direction, it is call a single-pass
condenser. If the water passes through one half of the
tubes in one direction and the other half in the opposite
direction, it is referred to as a two-pass condenser. A
single-pass condenser usually requires a larger water supply
than a two-pass condenser and generally results in a lower
temperature rise in the cooling water. Many condensers
have divided water boxes so that half the condenser can be
taken out of service for cleaning while the unit is kept
running under reduced loads. Condensers are periodically
cleaned mechanically as part of regular scheduled maintenance
procedures. Some plants employ continuous on-line mechanical
cleaning. Figure V-2 shows a typical single-pass condenser.
V-4
-------
I
Ul
I
OUT
(HOT)
STEAM FROM TURBINE EXHAUST
0
CONDENSATE
TO PUMP
o
73
r\
t
COOLING WATER IN
(COLD)
FIGURE V-2. Single-pass Condenser
-------
DRAFT
WATER USE AND WASTE CHARACTERIZATION 13Y_ CATEGORY
The results obtained on power plant wastes from visiting
twenty-two plants, sampling eight, and reducing and analyzing
the data do not differ substantially from those reported in
the "Development Document for Effluent Limitations Guidelines
and New Source Performance Standards for the Steam Electric
Power Generating Point Source Category" (14).
The majority of the water used in steam electric generating
plants is for condenser cooling water. Lesser amounts are
used for boiler makeup water, bearing cooling water,
equipment cleaning, and other miscellaneous purposes.
Figure V-3 shows a typical Steam Electric process diagram
with wastewater sources.
Waste discharges can be classified under two categories:
continuous discharges, and intermittent discharges. Wastes
are produced on a continuous basis from the following (if
applicable): cooling water systems, ash handling systems,
wet-scrubber air pollution control systems, and boiler
blowdowns. Waste discharges are produced intermittently by
boiler water pretreatment operations such as ion exchange,
filtration, clarification, and evaporation. Intermittent
discharges are also produced during miscellaneous equipment
cleaning operations and from sanitary and laboratory wastes.
The following discussion is a categorization and description
of water uses and waste discharges within typical generating
plants. Much of the following has been summarized from
Reference 14, which contains a more detailed discussion of
water use and waste characterization.
CONDENSER COOLING WATER
All condenser cooling systems can be classified as (1) once-
through, or (2) recirculating.
Once-Through Systems
In areas where large amounts of water are available from
natural sources, the simplest method of condensing steam is
to withdraw water from the source, pass it through a condenser
and discharge it back into the same source at a higher
temperature. Biocides such as chlorine or hypochlorites are
usually added to systems of this type to minimize biological
growth within the condenser. Once-through cooling systems
have no waste discharges to POTWs,
V-6
-------
Chemicals
Che«1cals
Water for
'Periodic Cleaning
To Atmosphere
Boiler Tube
Cleaning. Fire-
Side & Air
Preheater
Washings
Boiler Feedwater
Fuel-
Comb'n A1r--i
Bottom
Ash
Water
Fly Ash
Collection
and/or S0£
Scrubbing
Device
m ^ *\XXA* V\\%> •
Wastewater To
Treatment
|B1ovidownl4
Condensate Water
Wastewaterlt
Once Through
Cooling Water
Recirculatlng Cooling Water
O
[Blowdown )
Sanitary Wastes
Laboratory & Sampling
Wastes, Intake Screen
Backwash, Closed Cooling
Water Systems Construc-
tion, Activity
LEGEND:
< « »
Liquid Flow
Gas & Steam Flow
Chemicals
Optional Flow
FIGURE V-3 . Fossil-Fueled Steam Electric Power Plant-Typical Flow Diagram
-------
DRAFT
Recirculating Systems
If sufficient water is not available for a once-through
system, condenser cooling water must be recirculated within
the plant. This is accomplished by providing some sort of
artificial cooling device, such as a pond or a cooling tower,
to cool the cooling water by evaporating a portion of
it before recirculating it back to the condenser. Ponds are
used only where large areas of inexpensive land are available,
since a large plant may require over 1,000 acres of pond
surface. Cooling towers may be either of the wet or dry
types, and are used where sufficient land for ponds is
unavailable or too expensive. Since all cooling devices
(except dry cooling towers, which are rare) transfer the
process waste heat to the atmosphere by evaporation
additional water must be added to the system to make up
for these losses due to evaporation, drift and blowdown.
Various chemicals are added to recirculating cooling systems
to prevent biological growth in cooling towers and to control
scale accumulation and corrosion in condensers. These
include biocides such as chlorine, hypochlorites , and organic
chromates; and corrosion inhibitors such as organic phosphates,
sodium phosphate, chromates, and zinc salts.
Wastes that may be discharged to a POTW from recirculatinq
cooling systems originate from cooling tower blowdown
Blowdown is the discharge from the cooling tower of
a portion of water either constantly or intermittently
to prevent the concentration buildup of salts that may form
scale deposits within the condenser. This blowdown will
contain calcium, magnesium, and sodium cations in combination
with carbonate, bicarbonate, sulfate, and chloride anions.
Additionally, various amounts of the conditioning chemicals
will be present.
The rate of blowdown can be estimated by the use of the
following equation: (Ref. 1)
B = Ev - D(C-1 )
C-l
where: B is the blowdown rate; Ev is evaporation
rate; D is drift losses; and C is the
cycles of concentration defined as the
ratio of the concentration of a critical
chemical species in the blowdown to that
in the makeup water.
V-8
-------
DRAFT
The evaporation rate (Ev) from cooling towers averages
about 1.5 percent of the cooling water flow for every 10°C
rise in cooling water temperature as the water passes
through the condensers. The drift rate (D) for new cooling
towers is about 0.005 percent of the cooling water flow for
mechanical draft towers, and about 0.002 percent for natural
draft towers. Cycles of concentration (C) is an expression
of the buildup of any constitutent in the cooling water
system from its original value in the makeup water. In
practice, C is usually between 4 and 6. For very high
quality makeup water, C may be as high as 15, and for very
saline water, C may be as low as 1.2-1.5.
Figure V-4 shows typical once-through, and recirculating
cooling system flow diagrams. Figures, V-5 and V-6 show
two types of wet cooling towers.
Hater Use
Once-Through Systems. Seven of the twenty-two plants
surveyed use a once-through cooling system to remove the
waste heat from the process. The water usage in liters per
MWH at the plant studied is given below:
Plant No. Water Usage Liter/MWH
9369 1.65x105.
7420 3.23x105^
9163 2.01x105^
6387 3.68x105^
8356 2.57x105^
6421 5.32x10.5
6294 1 .34x105^
A similar but narrower range of water use for once-through
condenser cooling of 1.105^ to 3.5x105^ liters per MWH was
reported elsewhere (14). Plant No. 6421 has a higher
than normal water usage because of intermittant operation.
V-9
-------
SURFACE
WATER
DRAFT
EXHAUST STEAM
FROM TURBINE
CONDENSER
CONDENSATE
DISCHARGE TO
-^SURFACE WATER
EXHAUST STEAM
FROM TURBINE
CONDENSER
CONDENSATE
EVAPORATION
L
COOLING
TOWER
COOLING WATER
MAKEUP
WATER
FIGURE V-4 . Once-Through (top) and
Recirculating (bottom) Cooling
Systems
V-10
-------
DRAFT
WATER IN ,cr-
SPRAY ELIMINATOR
PUMP
=[
& 6'
— 6
6
AIR IN
BAFFLES
AIR IN
FIGURE V-5 . Diagram of Wet Forced-Air Cooling Tower
V-ll
-------
DRAFT
HOT WATER
DISTRIBUTION
DRIFT
ELIMINATOR
FILL—/^I^Z^E
AIR
INLET
COLD WATER
BASIN
FIGURE V-6
Natural-Draft Wet Cooling Tower
(Counter-Flow)
V-12
-------
DRAFT
Figure V-7 is a plot of once-through cooling water, corrected
to fit normal distribution, against the cumulative percentages
of involved plants expressed as probits (standard deviation
plus five). The statistical parameters for the three modes
of normal distribution examined are listed in Table V-l.
The statistical approach used is described in Appendix A
of this report. The results of the statistical analysis
suggest an almost perfect fit of the corrected data to the
three-parameter modes of normal distribution. This is
indicated by the coefficient of determination which measures
the "goodness of fit" of the regression line. This value
indicates that fitting of a least squares straight line
accounts for almost 100 percent of the data variance.
The water use data were also plotted against production rate
to determine the effect of the plant size on the quantity of
water used. Figure V-8 shows a log-log diagram of water
use for once-through condenser cooling as a function of
production rate. Also shown in Figure V-8 are the regression
line and the 95 percent confidence limits. The statistical
regression analysis coefficient expressed as logarithms are
given below.
Statistical Parameters Value
Slope -0.13
Intercept 6.14
Coefficient of determination 0.11
Standard error of estimated
water use on production rate 0.23
Standard error of intercept 0.17
Standard error of slope 0.94
The results of the statistical analysis suggest, at best,
a poor correlation between water use for once-through
cooling system and production rate. This is indicated by
the value calculated for the coefficient of determination
which indicates that a least squares regression line
accounts for only 11 percent of the data variance.
Although the overall trend suggests that the water use
may decrease slightly with increasing production rate,
this is not substantiated by the statistical analysis.
V-13
-------
10'
O)
O)
(0
•p
(O
DRAFT
10'
3.0
4.0
J|
5.0
PROBITS
6.0
7.0
FIGURE V-7 . Normal Distribution Diagram for ; Normalized
Once-Through Usage Data
V-14
-------
Table V-l. STATISTICAL PARAMETERS FOR THE THREE MODES
OF NORMAL DISTRIBUTION - ONCE-THROUGH CONDENSER COOLING
I
On
Mode of Normal
""•^^^ Distribution
^\^
Statistical ^""^^^
Parameter ^.^
Mean
Variance
3rd Moment
4th Moment
Coefficient of Skewness
Coefficent of Kurtosis
Correction Constant
SI ope
Intercept
Coefficient of Determination
99% Confidence Limit
Ari thmetic
xlO4
29.43
228.14
3681.88 -
1 .6x10
1 .05
3.08
Logarithmic
xlO4
26.3
1 .26
1 .006
1 .009
2.14
133.35
3 Parameters
Logari thmi c
XIU
16.91
1 .25
1 .0
1 .04
1 .0001
101 .49
-7.85641
2.66
0.13
0.994
236.59
O
70
-------
DRAFT
O)
en
re
t/i
TO
10
10"
10'
FIGURE V-8
J I
I
I
106 in6 in7
u Production Rate IU 10
(MWH)
Once-Through Cooling Water Use vs. Annual
Production Rate
V-16
-------
DRAFT
Recirculating Systems. Twelve of the 22 plants surveyed
use a recirculating condenser cooling system to remove
waste heat from the process. Waste heat is removed
from the cooling water by means of evaporation and blowdown.
Water usage in liters per MWH at the plants studied is given
below:
Plant No. Water Usage Liters/MWH
9600 1.64xlOi
9650 3.21x10^
9369 3.18x101
9371 3.44x10^
8816 2.14x101
9585 8.39x101
8696 2.24x10^
8135 1.41xl(H
8392 1.76xl04_
6293 4.1x101
7308 1.8x101
8875 2.36x103
Figure V-9 is a plot of recirculating condenser cooling
water, corrected to fit normal distribution, against
cumulative percent of involved plants expressed as probits
(standard deviation plus five). The statistical parameters
for the three modes of normal distribution examined are
listed in Table V-2. The statistical approach used is
described in Appendix A of this report. The coefficient of
determination calculated for the three parameter mode of
normal distribution, which measures "goodness of fit"
of the regression line to corrected data, indicates a
good fit to the normal distribution. This value indicates
that the least squares straight line accounts for 92 percent
of the data variance.
The water usage data was also plotted on log-log paper
versus the production rate to determine the effect of the
plant size on the quantity of water used. Figure V-10
shows the plotted data, the regression line, and the 95
percent confidence limits. The statistical regression
analysis coefficients expressed as logarithms are given
be!ow:
Statistical Parameters Value
Slope 0.06
Intercept 3.08
Coefficient of Determination 0.00
Standard error of estimated
water use on production rate 0.77
Standard error of intercept 2.09
Standard error of slope 0.37
V-17
-------
DRAFT
10'
o
CO
o
10'
-------
Table V-2. STATISTICAL PARAMETERS FOR THE THREE MODES OF NORMAL
DISTRIBUTION - RECIRCULATING CONDENSER COOLING
Mode of Normal
^^s. D i s t r i b u t i o n
Statistical ^^^^^^
Parameter ^^\^^
Mean
Variance
3rd Moment
4th Moment
Skewness
Kurtosi s
SI ope
Intercept
Coefficient of Determination
99% Confidence Limits
Correction Factor
Ari themti c
Normal
6.2
37.499
231.89 .
3.06x10°
1 .01
2.18
Logarithmic
Normal
3.89
1 .48
1 .07
1.15
2.56
114.6
3 Parameter
Logarithmic
3.06
1 .79
1 .00
1 .43
1 .00
266.13
4.07
0.003
0.916
7.3
-0.51236
i
to
-------
DRAFT
10'
10'
V *
C7>
ro
S-
d)
10°
I I
I I
__ 9l.Percentj:onf1denceJ.1«U
* a
Depression Li"g
O
95 Percent_ Confident LlmU __ ^
10
FIGURE V- 10 '.
10D 10° 10'
Production Rate (MWH)
Recirculating Cooling Water Use vs. Annual
Production Rate
V-20
-------
DRAFT
The results of the statistical analysis suggest no correlation
at all between water use for recirculating condenser cooling
and production rate. This is indicated by the low value
calculated for the coefficient of determination. This
analysis indicates that recirculating cooling water use is
independent of plant size.
Raw Waste Load
The raw wastes from the recirculating condenser cooling
process include:
• Chemical additives to control growth organisms
such as algae, fungi, and slimes;
• Chemical additives to inhibit corrosion; and
• Concentrations of solids, metallic salts,
and acidic and alkaline ions due to
evaporative loss.
Initially, all of these wastes are waterborne, but some,
such as suspended solids and metallic salts settle and
must be removed from cooling tower basins periodically.
Also, the settling of metallic salts cause scale formation
on condenser tubes and must be removed periodically usually
with an acid solution. The remainder of the raw wastes
are either removed from the wastewater by treatment
technologies, or are discharged to the sewer systems.
Waterborne wastes are shown in Table V-3 for plants 8392
8135, 8696, and 7308. The waterborne raw waste values
indicate that the major components in recirculating
condenser cooling streams are dissolved and total solids,
and chemical oxygen demand.
Wastewater Treatment
None of the plants using once-through condenser cooling
systems discharge to POTW's. Eleven plants using
recirculating condenser cooling systems discharge cooling
tower blowdown to the POTW. None of the eleven plants
discharging recirculating condenser cooling wastewaters to
POTW's employed any treatment technologies. Wastes were
discharged directly to the POTW without treatment.
V-21
-------
Table V-3. RAW WASTE FLOWS AND LOADINGS CONDENSER-COOLING SYSTEMS
PLANT NO.
WASTEWATER SOURCE
FLOW
PARAMETER
EOD5
Provide (Bromate)
COD
Chroniun
Cb rn~\ um+6
Copper
CyanH» (Total)
Iron
Nickel
Oil arc Grease
Phosph 3 te 'Total )
Total Dissolved Solids
Total Sjspended Solids
Total Solids
Surfactants
Zinc
_^_^_____—
8392
Cooling Tower
Rlnwdown
L/Oay L/MWH
238455.0 745.81
mg/1
1 .42
9.8
4.9
3.3
0.02
0.02
0.48
0.03
1.0
3.25
886.0
2.9
889.0
1.5
g/MWH
10.4
7.3
3.65
2.46
0.01
0.01
0.35
2.43
660.78
2.16
660.8
1.11
8135
Cooling Tower
Slowdown
I/Day
53959.0
mg/ 1
7.09
102.91
0.02
0.004
0.014
7.43
943.45
3.89
946.73
0.48
L/MWH
321.51
S/MWH
2.28
33.14
0.001
0.005
2.39
303.74
1.25
304.85
0.15
8696
Cool-ing Tower
Slowdown
L/oay L/MWH
217788.9 18.03
nig/T
22
25.2
<0.02
0.012
0.35
<0.005
0.32
<0.03
2.4
0.06
2860
33
2893
0.09
g/MWH
0.39
- - - -
0.45
0.0002
0.002
0.005
0.043
0.001
51 .5
0.59
52.19
0.001
7308
Cooling Tower
Slowdown
L/Day
(1)
mg/ I
5.7
- - - -
64
1 .39
0.76
0.7
0.025
1.63
0.04
1.9
0.95
5111
59
5170
0.7
L/rlWH
(1)
g/MWH
(1)
8231
Cooling Tower
Blowdown
L/Day
580.365.4
mg/1
0.009
0.1'
0.15
0.03
1 .0
8.3
0.02
L/MWH
555.37
g/MWH
0.004
0.06
0.08
4.0
0.01
9650
Cool 1 ng Tower
Blowdown
L/LmV L/MKH
' 1067370.0 1292.2
mi)/ 1
0.07
0.044
0.05
0.29
4.0
0.08
16.0
2T04
g/nwH
0.09
0.05
0.06
0.37
5.16
0.1
20.67
2.63
o
ro
ro
(1) Flow could not be measured.
-------
DRAFT
Effluent Waste Loads
Information was not obtained on the composition of
recirculating condenser cooling wastes after treatment since
no plants performed any treatment before discharge to the
POTW. Waterborne wastes present in the recirculating
condenser cooling discharge to the POTW can be found in
Table V-3.
WATER TREATMENT
To compensate for steam losses through leakage and boiler
blowdown, additional water must be added to the boiler.
Particularly in high-pressure boilers; this water must be
of extremely high quality, and must undergo extensive
pretreatment. If the water is taken from a municipal
supply, pretreatment may consist of dual media filtration,
reverse osmosis filtration, and demineralization. Older,
low-pressure steam plants may pretreat boiler makeup water
solely with evaporators. Some steam electric plants treat
water by clarification and softening followed by
demineralization. A more detailed description of those
treatment schemes and their associated wastes follows.
Clarification is a process for removing suspended solids
and dissolved impurities. Chemical coagulants such as
alum, ferrous sulfate, ferric sulfate, sodium aluminate,
and polyelectrolytes are added to the water to aid the
agglomeration of these impurities into larger, heavier
particles. The particles are allowed to settle, and the
clarified water is drawn off and filtered. Softening
may be performed prior to clarification to precipitate
calcium and magnesium. Clarification and softening wastes
consist of sludges and filter washes. Clarifier sludges
consists of either alum or iron salts, and softening sludges
consist of calcium carbonate and magnesium hydroxides.
Filter washes contain suspended solids either carried over
from the clarifier or contained naturally in the unclarified
water.
Demineralization (ion exchange) is a process that removes
mineral salts by adsorption on a resin. Two types of
resins exist: cationic (for the removal of cations), and
anionic (for the removal of anions). These resins may be
used separately, (one following the other), or they may be
combined in a mixed-bed (demineralizer). After a period
of use, ion exchange resins become saturated with adsorbed
ions, and must be regenerated. Anionic resins are regenerated
V-23
-------
DRAFT
with sodium hydroxide solution followed by water rinse to
remove residual alkalinity. The regeneration waste will have
a high pH and will contain the adsorbed anions, which are:
sulfate, chloride, nitrate, phosphate, carbonate, and
bicarbonate. Cationic resins are regenerated with sulfuric
acid, and the regeneration waste from those units will have
a low pH and will contain calcium, magnesium, potassium, and
sodium ions.
Evaporation is simply a distillation process for the
removal of dissolved impurities. Evaporators consist of
a horizontal vessel heated by a waste heat source, which
is usually exhaust steam from the turbines. Steam from
the evaporation of water in the vessel is drawn off and
condensed in an external condenser. To prevent a
concentration buildup of salts which contribute to scaling
problems within the vessel, a portion of the water is drawn
off as blowdown intermittently. This blowdown has a high
pH, and contains the same chemicals present in the raw water
feed, which have been concentrated by a factor of three to
five. Calcium carbonate and calcium sulfate precipitates
may also be present in the blowdown if present in the water
feed in sufficiently high concentrations. Phosphate is
sometimes added to the raw water feed to lessen the
precipitation of calcium salts (14).
Reverse osmosis is a process used by some plants to remove
dissolved salts. The technique consists of forcing water
through a semipermeable membrane under a pressure greater
than the osmotic pressure of the dissolved salts. The salts
are concentrated on one side of the membrane and the purified
water is collected on the other. The concentrated salt
solution (brine) is discharged as a waste.
Chemical Additions. After pretreatment, various chemicals
are added to the boiler makeup water. These include
hydrazine sulfite (to remove dissolved oxygen), sodium
phosphate (to prevent scale formation by precipitating
calcium and magnesium salts), and sodium hydroxide (to
control pH).
Figure V-ll shows six (6) commonly used water treatment
methods. .
V-24
-------
DRAFT
Raw Water
Add
CATION
Sri _
1
DEGASI-
FIER
i
Caustic
AN I ON
Delonized Viater
—— . )•-
Haste
Separated-Bed Ion Exchange Demineralizer
Raw Water
Caustic
Acid
MIXED
RESIN
Waste
Deionized Water
Mixed-Bed Ion Exchange Demineralizer
Pressure
Feed
Hater
High Pressure
Pump
1
Membrane
-Permeate
(Product
Water)
Regulating
Valve
Concentrate (Wastewater)
Reverse Osmosis Membrane Filter
FIGURE 11. Commonly Used Water Treatment Methods
V~25
-------
DRAFT
Raw Mater
Slowdown
Wash,.
\ [
FILTER
t
Wastewater
Filtered
Water
S-^[^H
1
Oelonlzed
Water
lastewater
Coagulation-Filtration Water Treatment Process
Condensed
Boiler
Slowdown
Evaporator
Blowcov;n
Evaporation Process
Treatment
Chemicals
Raw Waterv
CLARIF1ER
Clear,
Water
.Sludge
Clarification Process
FIGURE 11. Commonly Used Water Treatment Methods
(Conti nued)
V-26
-------
DRAFT
Water Use
Boiler Makeup Water. Sixteen of the twenty-two plants
surveyed provided information on their boiler makeup
water usage. The water use in liters per MWH at the
plants studied is given below.
Plant No. Water Usage Liters/MWH
9650 36.76
9369 79.56
9371 36.73
8816 29.93
9585 1.59x101
8696 4.15
8135 4.03x101
9163 1.32x10?
6387 1.08x103.
8356 1.78x101
8392 1.19xl03_
6293 6.81
7968 3.46xl02_
6421 4.58x101
6294 1.06x101
Figure V-12 is a plot of the boiler makeup water usage,
corrected to fit normal distribution, against the cumulative
percent of involved plants expressed as probits. The
statistical approach used is described in Appendix A of
this report. The coefficient of determination calculated
by the three parameter mode of normal distribution, which
measures the "goodness of fit" of the regression line to
the correlated data, indicates an almost perfect fit to
the normal distribution. The value indicates that the
least squares straight line accounts for appoximately
97 percent of the data variance. (See Table V-4).
V-27
-------
DRAFT
10"
10'
O)
CD
o>
4J
IO
10'
10
4.0
5.0
6.0
7.0
PROBITS
FIGURE V- 12 . Normal Distribution Diagram for Normalized
Boiler Makeup Water Usage Data
V-28
ID
-------
Table V-4. STATISTICAL PARAMETERS FOR THE THREE MODES OF
NORMAL DISTRIBUTION-BOILER MAKEUP
l
ro
to
Mode of Normal
^"""••^Distribution
Statistical ^^"---^^
Parameters — »^^^
.Mean
Variance
3rd Moment
4th Moment
Skewness
Kurtosis
Slope
Intercept
Coefficient of Determination
99% Confidence Limits
Correction Factor
Arithmetic
Normal
3.7xl02
4.0x10%
5.6xlO?n
l.lxlO10
2.2
6.98
Logarithmic
Normal
97.72
3.52
1.12
5.55
1.32
311.17
3 Parameter
Logarithmic
93.33
3.88
0.9999
7.83
0.9997
375.84
8.04
0.003
0.964 .
1,7x10^
-1 .20465
o
73
-------
DRAFT
The water usage data was also plotted on log-log paper
versus the production rate to determine the effect of the
plant size on the quantity of water used. Figure V--13
shows the plotted data, the regression line,and the 95
percent confidence limits. The statistical regression
analysis coefficients expressed as logarithms are given
be!ow:
Statistical Parameters
Slope
Intercept
Coefficient of Determination
Standard error of estimated
water use on production rate
Standard error of intercept
Standard error of slope
Value
-0.92
7.1
0.47
0.57
1.45
0.26
The results of the statistical analyses suggest a fair
correlation between water use for boiler makeup and
production rate. This is indicated by the value calculated
for the coefficient of determination which indicates that
the least squares regression line accounts for approximately
50 percent of the data variance.
Demineralizer
presented
usage. The
studied is given
Thirteen of the twenty-two plants surveyed
information on their demineralizer system water
water usage in liters per MWH at the plants
below:
PlantNo.
9650
9369
9371
9585
8696
9163
6387
8356
8392
6293
8875
6421
6294
Water Usage, Liters/MWH
65
17
27
3
4
18
13
4
7
75
51
55
24xl02_
56
38
46
22x102.
1
9.01
11.35
39.23
5.69
V-30
-------
10
en
(O
01
4->
fC
10'
10
\-
FIGURE V- 13
io5 iob 10'
Production Rate (MWH)
Boiler Makeup Water Use vs. Annual Production
Rate
V-31
-------
DRAFT
Figure V-14 is a plot of the demineralizer water use, corrected
to fit normal distribution, against the cumulative percent
of involved plants expressed as probits. The statistical
parameters for the three modes of normal distribution
examined are listed in Table V-5. The statistical approach
used is described in Appendix A of this report. The
coefficient of determination calculated by the three
parameters mode of normal distribution, which measures the
"goodness of fit" of the regression line to the corrected
data, indicates an almost perfect fit to normal distribution.
This value indicates that the least squares straight line
accounts for 97 percent of the data variance.
The water usage data was also plotted on log-log paper
versus the production rate to determine the effect of
plant size on the quantity of water used. Figure V-15
shows the plotted data, the regression line, and the 90
percent confidence limits. The statistical regression
coefficients expressed as logarithms are given below.
Statistical Parameters Value
Slope 0.03
Intercept 1 • 52
Coefficient of Determination 0.00
Standard error of estimated
water use on production rate 0.65
Standard error of intercept 1.76
Standard error of slope 0.31
The results of the statistical analysis suggest no correlation
at all between water use for the demineralizer system and the
production rate. This is indicated by the value calculated
for the coefficient of determination which indicates that
a least squares regression line accounts for zero percent of
the data variance. From this analysis, it may be assumed
that demineralizer water use is independent of plant size.
V-32
-------
10'
10'
DRAFT
0)
in
Ol
10
3.0
4.0
I
5.0
PROBITS
6.0
7.0
FIGURE V-14. Normal Distribution Diagram for Normalized
Ion Exchange Water Usage Data
V-33
-------
TABLE V-5. STATISTICAL PARAMETERS FOR THE THREE MODES
OF NORMAL DISTRIBUTION - DEMINERALIZER
Mode of Normal
^""-•s.D i s t r i b u t i o n
Statistical ^^--^^
Parameters ^^^^
Mean
Variance
3rd Moment
4th Moment
Skewness
Kurtosis
SI ope
Intercept
Coefficient of Determination
99% Confidence Limits
Correction Factor
Arithmetic
Normal
74.28 4
1 .69x10^
4.26xlOX
1 .43xlOy
1 .95
5.05
Logarithmic
Normal
23.99
2.29
1 .59
2.29
8.71
645.65
3 Parameter
Logarithmic
13.18
5.37
1 .00009
28.18
1 .0001
501 .19
10.97
0.00009
0.96981
20.26
- 4.30691
GO
-------
~ 10
en
to
j-
-------
DRAFT
Raw Waste Load
The raw wastes from the water treatment process include:
• Mineral salts, suspended solids and other
constituents removed from the raw water
supply.
• Chemicals used by the water treatment units.
Of the twenty-two plants visited, three use hot lime-soda
ash softening and zeolite ion exchange, two use hot
lime-soda ash softening, filtration, and zeolite ion
exchange, two use reverse osmosis and deionization,
twelve use cation-anion ion exchange, one uses
deionization and evaporation, one uses hot lime-soda
ash softening, zeolite ion exchange and evaporation, and
one uses deionization and evaporation.
Solid wastes are not generated in large quantitites during
the water treatment process. The major source of solid
wastes are calcium carbonate and magnesium hydroxide from
the lime-soda ash softening processes. Waterborne wastes
for plants in terms of grams per MWH are given in
Table V-6.
Wastewater Treatment
Fifteen plants discharge water treatment waste streams to
POTW's. Five of these plants practice some type of
pretreatment before discharge. Plant 6293 uses lime
settling; plant 9369 uses equalization and neutralization;
plant 7308 uses equalization, neutralization, and settling;
and plant 8696 uses equalization, settling, and oil skimming
Eff1uent Haste Loads
Table V-7 shows the composition of pretreated wastewater
discharge to the POTW in terms of concentration and
waste loads for plant 6293.
BOILER SLOWDOWN
To prevent the accumulation of calcium and magnesium salts
on the internal boiler surfaces, phosphates are usually
added to precipitate the salts. The precipitate is removed
continuously orintermittently by withdrawing a portion of
the boiler water as blowdown. Slowdown wastes have a high
V-36
-------
Table V-6. RAW WASTE FLOWS AND LOADINGS - WATER TREATMENT
PLANT NO.
UASTEWHtER SOUHCC
fLOU
PARAMETER
CODj
COD
Chroraiu*
Chronlun'6
Copper
Cya.iide (Total)
i ron
HlckCl
Oil an'd Grease
Phosphite (Total)
Total Dissolved Solids
fotll Solid!
Zinc
I2»J
Line Softener
L/oay
1635).?
.9/1
48.0
37.2
0.09
0.006
0.06
0.005
9.0
0.07
1.0
188
1780
1968
0.010
0.12
L/MUH
68.13
g/MUH
3.27
2. S3
0.006
0.004
0.6
0.004
12.8
121.27
134.08
0.001
0.008
8135
De«1neallzer
Effluent
L/Day
4277.05
rng/i
1.0
1.49
9 8
0.02
0.002
0.02
0.005
0.02
0.03
1.0
0.16
0.16
....
L/MUH
3.05
9/HUH
0.003
0.004
0.03
0.05
174
1.0
174
0.011
0.02
6392
Oenlneal Izer
process water)
L/Oay
"9/1
1.0
1.02
2 0
0.02
0.005
0.02
0.005
0 07
0.03
1.0
0.05
174
1 0
174
0.011
0.02
L/MUH
(1)
9/MUh
6387
Backwash
l/O.ay
17168.7
«g/l
1.8
.---
200
0.11
0.004
0.15
0.014
10 4
0.09
1 0
1004
9440
10444
0.32
L/HHH
47.69
9/HUH
0.08
9.53
0.005
0.007
0.0006
0.49
0.004
47.88
4S0.2
98.08
0.015
6387' s
(slug
L/Day
7570
«g/i
10 4
561
0.1
0.007
0.12
O.OOS
0.44
0.25
1.0
22980
44
23024
0.09
L/MUH
252 33
g/HUH
2.62
141.55
0.02
0.001
0.03
0.0011
0.11
0.06
5798.6
11.1
S809.7
0.02
6387
L/Dav
40878
•g/1
15.2
76.0
0.02
0.005
0.02
0.006
0.38
0.03
1.0
6.20
2228
93
2321
0.11
CVr.M
113.55
g/M»H
1.72
8.62
O.OiOi
0 002
o.ooot
0.043
0.7
252.9
IDS. 6
263.5
0.01
6231
Oenfneraltzer
L/Ojy
22710
mg/1
0.07
0.006
0.02
1.26
0 14
13.2
31
0.06
L/MUH
21.73
g/MUH
0.001
0.0001
0.02
0 003
0.28
0.63
0.001
8231
Oenlnerallzer Backwash
1/Da.y
2C73.8
•a/I
0.02
0.005
0 02
0.03
0 03
8.2
6.8
0.38
0.01
L/MUH
2.46
Q/fUH
0.02
0.016
0.0009
9650
Combined DemlneraHzer
Fffl,.»nf
LyUs/
5109 T.
iro/1
0 2
0 01
0.59
9.46
0.2
1 0
16.7
0.21
1/-UH
ei e
e/Mm
0. 31
0 CC.t
0 O'S
0 58
0 01
1 .03
0 01
CO
(I) Flow could not !>• ntasured.
-------
DRAFT
Table V-6. RAW WASTE FLOWS AND LOADINGS - WATER TREATMENT
(CONTINUED)
PLANT NO.
WASTEWATER SOURCE
FLOW
PARAMETER
BOD5
Bromide (Bromate)
COD
Chromi urn (Total )
Chromi um+6
Copper
Cyanide (Total )
Iron
Nickel
Oil and Grease
Phosphate (Total)
Total Dissolved
Solids
"otal Suspended
Sol ids
Total So 1 i ds
Surfactants
Zinc
8696
Cation Demin-
e r a 1 i z e r
VReqeneration
L/Day L/MWH
\ll355m 0.94
mq/1 q/MWH
6.0 0.005
0.03 0.00002
13.6 0.012
0.07 0 00006
0.008 Neg.
1.3 0.001
<0 .005
1.02 0 009
<0.03
<1 .0
14.0 0.013
3960 3.72
30 0.03
3990 3.75
<0.01
0.03 0.00002
7308
Evaporator
Slowdown
L/Day L/MWI
(1) (1)
mg/1 q/MWh
5.16 (1)
20.8
0 08
0.036
2.61
n 028
0 22
<0.03
1.9
12.6
2532.66
14.5
2547.16
0.44
7308
Zeol i te
Softener Back-
Wash
L/Day L/MWH
4920.5(2) 0.29
mg/1 q/MWH
27 0.008
0.07 Neg
384 0.11
-------
Table V-7. EFFLUENT FLOWS AND LOADINGS - WATER TREATMENT
GO
IO
PLANT NO.
WASTEWATER SOURCE
FLOW
PARAMETER
BOD5
Bromide (Bromate)
COD
Chroml um
Chromium^
Copper
Cyanide (Total)
Iron
Nickel
Oil and Grease
Phosphate (Total)
Total Dissolved Solids
Total Suspended Solids
Total Solids
Surfactants
Zinc
6293
Lime Softener Effluent
L/Day L/MWH
lfi.151.2 68.13
mg/1
1.5
5.9
0.02
0.026
0.02
0.005
1.23
0.03
1.0
152.0
245.0
397.0
0.011
0.2
g/MWH
0.1
0.4
0.001
0.001
0.001
0.08
10.35
16.69
27.04
0.0001
0.0001
8696
Diluted Dem1neral1zer
L/Day L/MWH
54504 4.57
mg/1
34.0
~ ™ ~ ""
81 .0
0.05
<0.005
0.88
«0.005
3.0
«0.03
1.80
954
219
1173
0.18
g/HWH
0.15
0.36
0.002
0.004
0.01
0.008
4.30
0.98
5.28
0.0008
8237
Holding Tank
Effluent
L/Day L/MWH
15518.5 14.85
mg/1
0.05
0.007
b.02
0.85
0.09
9.36
25.02
0.04
g/MWH
0.0007
0.0001
0.020
0.001
0.13
0.35
0.0005
-------
DRAFT
pH and a high dissolved solids concentration. Slowdown
from boilers treated with phosphate will contain hydroxide
alkalinity and phosphate, and blowdown from boilers treated
with hydrazine will contain ammonia.
Raw Waste Load
The raw wastes from boiler blowdown include:
• Chemical additives to remove oxygen;
• Chemical additives to prevent scale or
inhibit corrosion; and
• Concentrations of dissolved solids and
other constitutents present in the
boiler feedwater.
Boiler blowdown does not generate large quantities of
solid waste. Sludge, which consists of precipitated
calcium and magnesium salts, is maintained in a fluid
form and removed by the blowdown.
Waterborne wastes for two plants in terms of grams per MWH
are given in Table V-8.
The waterborne raw waste values indicate that the major
components by weight in boiler blowdown streams are
dissolved solids, chemical oxygen demand, and total
phosphates.
Wastewater Treatment
Thirteen plants discharge boiler blowdown to POTW' s, of
which, three practice some type of pretreatment. Plant 9369
uses equalization and neutralization, plant 7116 uses
equalization, neutralization and settling and plant 7308
uses equalization, neutralization and oil skimming.
Eff1uent Haste Loads
Information was not available on treated waste streams from
boiler blowdown.
V-40
-------
Table V- 8 . RAW WASTE FLOWS AND LOADINGS - BOILER SLOWDOWN
PLANT NO.
WASTEWATER SOURCE
FLOW
PARAMETER
BODg
Bromide (Bromate)
COD
Chromium (Total)
Chromi um+6
Copper
Cyanide (Total )
Iron
Nickel
Oil and Grease
Phosphate (Total)
Total Dissolved Solids
Total Suspended Solids
Total Solids
Surfactants
Zinc
6293
Boiler Slowdown
L/DAY
17030.4
mg/1
11.7
157.0
0.02
0.007
- 0.19
0.005
1 .4
0.03
2.2
18.7
1405.0
2.7
1407.7
0.05
L/MWH
70.96"
g/MWH
0.83
11 .1
0.0001
0.01
0.1
0.15
1 .32
99.7
0.19
99.9
0.003
8392
Boiler Slowdown
L/DAY
1665.4
mg/1
10.8
2.0
0.02
0.009
0.06
0.014
0.08
0.03
1 .0
19.8
118.0
6.9
125.0
0.02
L/MWH
5.20
g/MWH
0.06
0.0001
Neg .
0.0003
Neg.
0.0004
0.1
0.61
0.036
0.65
0.0001
8231
Boiler Slowdown
L/DAY
5715
mg/1
0.02
0.005
0.02
0.03
0.03
14.8
0.05
31
0.01
L/MWH
5.47 '
g/MWH
0.08
0.17
9650
Boiler Slowdown
L/DAY
(11
mg/1
0.02
0.005
0.02
0.03
0.03
5.3
0.05
8.3
0.02
t L/MWH
(])
g/MWH
Neg.
(1) Flow could not be measured.
-------
DRAFT
MAINTENANCE CLEANING
Boiler Tubes. Boiler tubes must be cleaned occasionally
to remove accumulations of scale. A multitude of cleaning
mixtures are used to accomplish this purpose with a
minimum of effort. These include: alkaline cleaning
mixtures with oxidizing agents for copper removal, acid
cleaning mixtures, alkaline chelating rinses, organic
solvents, and proprietary solvents. Wastes from these
cleaning operations will contain iron, copper, hardness,
and phosphates. In addition to these constituents, wastes
from alkaline cleaning mixtures will contain ammonium
ions, oxidizing agents, and high alkalinity; wastes from
acid cleaning mixtures will contain fluorides, high
acidity, and organic compounds; wastes from alkaline
chelating rinses will contain high alkalinity and organic
compounds; and wastes from most proprietary processes will
be alkaline and will contain organic and ammonium compounds.
Boiler Fireside Cleaning. The fireside surface of boiler
tubes collects airborne dust, fuel ash, and corrosion
products. These materials are removed from time to time
with high-pressure hoses. Alkaline chemicals may be used
to make the cleaning more effective.
Wastes from this operation will be more or less acidic
depending on the sulfur content of the fuel, and will
contain hardness, suspended solids, and some metals.
Air Preheater Cleaning. Air preheaters are used to heat
ambient air that is used for combustion, and collect soot
and fly ash. High-pressure hoses are used to remove these
materials. The wastes from this operation will be more
or less acidic, depending on the sulfur content of the fuel,
and will contain suspended solids, magnesium salts, iron,
copper, nickel, and chromium. Vanadium may also be present
if the plant is oil-fired.
Stack Cleaning. High pressure water is used to clean fly
ash and soot from stacks. The frequency that this
cleaning is required is dictated by the fossil fuel used.
Wastes from this operation may contain suspended solids,
metals, oil, and high or low pH values.
V-42
-------
DRAFT
Cool Ing Tower Basin Cleaning. Deposits of carbonates on
the bottoms of cooling towers and growth of algae on
cooling towers are removed occasionally with water. The
wastes contain suspended solids as a primary pollutant.
Miscellaneous Small Equipment. Occasional cleaning of
plant equipment such as condensate coolers, hydrogen
coolers, air compressor coolers, and stator oil coolers
is performed. Detergents, wetting agents, and hydrochloric
acid are often used during cleaning. Wastes from these
operations will contain suspended solids, metals, oil, and
1ow or high pH.
Raw Waste Load
The raw wastes from maintenance cleaning consist of the
cleaning solution and the material removed from the
equipment. Boiler fireside, air preheater, and boiler tube
cleaning account for most of the wastewater generated in
maintenance cleaning. No plants were performing maintenance
cleaning during the time of our visitation and sampling.
Typical waterborne wastes are shown in Table V-9 for
wastewaters from air preheater boi1er fireside, and tube
cleaning. This information was obtained from Reference 14.
Information was not available on cooling tower basin and
stack cleaning wastewaters.
The major components by weight in the three cleaning waste
streams are dissolved solids, hardness, metals, chlorides
and sulfates.
Water Use
At infrequent intervals, certain power pi ants components such
as condensate coolers, oil coolers, compressors, boilers,
etc. are chemically cleaned with a solution of hydrochloric
acid, or a detergent. Typical flow rates are summarized
on page V-45 (14).
V-43
-------
DRAFT
Table V-9. RAW WASTE FLOWS AND LOADINGS - MAINTENANCE CLEANING
No. of Plants
Wastewater Source
Cleaning Frequency
(#/vr)
Flow (1000 liter)
Parameter (Kg)
BODr
UUU5
Bromide (Bromate)
COD
Chromi urn (Total )
Chromi um
Copper
Cya ni de ( Tota 1 )
I ron
Nickel
Oil and Grease
Phosphate (Total)
Total Dissolved
Solids
Total Suspended
Solids
Total Solids
Su r f a c tan t s
Zinc
7 plants
Air Preheater
4-12
163-2,271
Kg
0-6 82
2.6-15.9
0.21-26.88
0-2.02
0.97-3862
8.14-170.38
0.02-2.66
1 ,448-20,096
217-4,898
1,188-29,744
0.13-11 .36
2 olants
Boiler Fireside
2-8
91-2,725
Kg
o
8.63-515.00
0.01-0.45
0-0.11
13.63-408.90
0-13.63
0.12-5.04
1 ,363-15,948
54.07-1 ,736
1 ,817-18,551
0.91-13.04
7 nlants
Boiler Tubes
0-2
568-18,622
Kg
0.45-19,387
0.21-10,524
0.06-931 ,185
0.51-595.96
42,592-133,826
0.02-3.48"
111 .11-43,598
0-1 ,590
111 .11-48,868
C. 35-391 ,098
V-44
-------
DRAFT
Waste
Stream
Waste
Flow or Volume
Frequency
Typical Flow
or Volume
Chemical Cleaning
Boiler Tubes
3-5 Boiler
Volumes
Once/7 Months- 1 boiler per
once/100 mos. 1-2 hours
Boiler Fire- 24-720x10 gal
side
Air Preheater 43-600xl03gal
No Date
2-8/yr
4-12/yr
300,000 Gal
200,000 Gal
Misc. Small
Equi pment
Stack
No Data
Cooling Tower No Data
Basin
Wastewater Treatment
Four plants discharge maintenance cleaning wastewaters to
POTW's of which two utilize some type of pretreatment
Plant 6387 uses settling and plant 8696 uses dilution,
equalization, settling and oil skimming. Three plants
have outside contractors haul away boiler cleaning wastes
Effluent Waste Loads
Information was not obtained on the composition of
maintenance cleaning wastes after treatment.
V-45
-------
DRAFT
ASH-HANDLING SYSTEMS
One of the products of the combustion of coal and oil in
electric utilities is ash. Ash which falls to the bottom
of the furnace is called bottom ash; ash which leaves the
furnace with the flue gas is called fly ash. Fly ash is
usually collected from coal-fired units with electrostatic
precipitators and from large oil-fired units with cyclones.
The function of ash-handling systems is to remove accumulated
bottom ash and fly ash.
Two types of ash-handling systems exist: dry systems and wet
systems. Dry systems use pneumatic conveyance devices for
the transport of ash and are not a source of liquid wastes.
Wet systems use water for the transport of ash, transporting
the ash-water slurry through sluices and in many cases,
discharging it into a settling pond or basin.
Wet systems are either of the open type or the closed type.
Open systems discharge supernatant from the settling basin
into either a receiving water or a POTW. Closed streams
recycle the supernatent back to the ash-transporting sluice
for reuse. Figure V-16 shows a flow diagram for recirculating
bottom ash system. Periods of extended rainfall may cause
problems with closed systems, since some water may have to
be withdrawn from the settling basin and discharged. Similarly,
extended periods of dryness may evaporate excessive amounts
of water from the settling basin, requiring the addition of
supplementary water to the system.
Ash pond overflows from coal-fired plants contain a wide
variety of constitents whose concentrations can vary widely
depending on the particular coal used. Generally, the
overflows contain high levels of dissolved solids, suspended
solids, hardness, sulfate, sodium, magnesium, chloride, and
alkalinity. Other trace metals originally present in the
coal may also be present.
Ash is produced in oil-fired plants in very small quanitities.
It has been found that oil ash does not settle as well as
coal ash. In some utilities, the oil fly ash is recycled
into the furnace, increasing efficiency and eliminating the
disposal problem. Ash pond overflows from oil-fired plants
have some of the same characteristics as those from coal-
fired plants, and may additionally contain high concentrations
of vanadium.
Table V-10 contains an itemization of the types of ash
handling systems used by the plants that were visited.
V-46
-------
EVAPORAT]
ON LOSS
ASH HANDLING
SYSTEM
DRAFT
EVAPORATION
LOSS MAKE-UP
RAINFALL
i
SETTLING POND
OVERFLOW
RECYCLE
ASH SLUDGE FOR
DISPOSAL
FIGURE V-16. Flow Diagram for Reelrcul ating Bottom
Ash System
V-47
-------
Table V-10. ASH DISPOSAL METHODS
-£»
CO
PLANT NO.
9600
9650
9369
9371
7485
8816
9585
7116
8696
8135
9163
6387
8392
6293
7308
8875
7968
6421
6214
6294
TYPE OF PLANT
Oil and Gas
Oil and Gas
Oil and Gas
Oi 1 and Gas
Coal, Oil, and Gas
Oi 1 and Gas
Gas
Oil and Gas
Oi 1 and Gas
Oil and Gas
Coal
Coal
Gas
Coal
Oil
Oil and Gas
Coal and Gas
Oil and Gas
Coal
Coal and Gas
ASH DISPOSAL SYSTEM
FLY ASH BOTTOM ASH -
None Required
1 2
3 4
3 2
3 4
1 2
None Required
3 4
3 2
None Required
3,5 4
3 6
None Requi red
3 7
None Required
1 2
3 7
None Required
8 8
3 8
o
73
Key: (1) Soot blowing steam
(2) Fireside washing
(3) Dry collection system from electrostatic and/or mech-
anical precipitators , ash then hauled to landfill.
(4) Dry collection system-ash landfilled.
(5) Air wash in stack to control fly ash-discharges to
POTW
(6) Wet collection system with settling sump-(overf1ow
from sump goes to POTW)
(7) Vacuum system using steam, ash landfilled, condensate
from steam goes to POTW.
(8) Wet system discharging to surface water. : ~
-------
DRAFT
Hater Use
Of the twenty-two plants visited in this study, only
four used water to convey fly and bottom ash to
ash ponds; the remaining plants use dry ash transport
systems. Of the four plants utilizing wet systems, all
were coal-fired. Plant 9163 uses 2.65x102, liters per
MWH, the only plant using water for fly ash transport.
The other three plants 6387, 8356, and 6294, respectively
use 43.09, 3.61x102^ and 11.39 liters per MWH for bottom
ash transport.
Raw Waste Load
Oil-Fired Plants. Fuel oils contain only about one percent
of the amount of ash commonly found in coal, consequently,
ash disposal problems from oil-fired plants are minimal.
Fly Ash. Many of the oil-fired plants visited used
mechanical cyclones to remove fly ash from the flue gases.
A dry system is usually used to remove the collected ash.
In other plants, no fly ash collection system is necessary
because of the low ash content of the oil used. In these
plants, most of the ash in the flue gases collects on the
interior surfaces of the boiler and is removed by high
pressure steam (soot blowing steam), and passes through the
Stack to the atmosphere.
Bottom Ash. Some of the oil-fired plants visited needed only
occasional fireside washing to remove bottom ash, other
plants had dry collection systems that removed ash for
land disposal .
Coal-Fired Plants. The amount of ash produced by coal-
fired plants is much greater than that produced by oil-
fired plants, requiring the use of more complex ash-handling
systems.
Fly Ash. Electrostatic precipitators or mechanical cyclones
are used in most of the coal-fired plants to collect fly
ash. The collection systems from these units are usually
dry, and the final ash disposal is on land. One plant,
No. 9163, used an additional system for fly ash control,
consisting of a wash in the stack that discharged excess
fly ash to a POTW.
V-49
-------
DRAFT
Bottom Ash. Methods for disposing of bottom ash varied
widely among the coal-fired plants that were visited.
Plants 7485 and 9163 used dry collection systems
for the land disposal of bottom ash. Plant 6387 was the
only plant visited that used a wet transport system in
combination with a settling sump. Two plants No. 6293
and 7628 used a vacuum collection system with steam. One
plant, No. 6294, used a wet collection system discharging
to surface water. Plant No. 6214 mixed both bottom
ash and fly ash with once-through cooling water.
Table V-ll shows raw waste loading for two plants,
6293 and 6387.
Wastewater Treatment
Oil-Fired Plants. Because of the small quantities of ash
produced by oil-fired plants, none of the visited plants
had ash treatment systems.
Coal-Fired Plants. Only one plant, No. 6387, used a
settling basin in conjunction with a wet ash transport
system. Most of the other coal-fired plants had no
need for an ash treatment system, since these plants used
dry collection systems, followed by land disposal.
Eff1uent Waste Loads
Oil-Fired Plants. Effluents from ash cleaning of oil-
fired plants are present for those plants which used fireside
cleaning for ash removal.
Coal-Fired Plants. Plant No. 6387 is the only visited plant
that discharged a significant amount of waste
from an ash handling system to a POTW. The discharge
consists of the overflow from the ash settling sump. Treated
effluent is shown in Table V-12.
DRAINAGE
F1oor and Yard Drains. Floor and yard drains collect wastes
from leakage and numerous cleaning operations, and may
discharge to a POTW. The waste will contain dust, fly ash,
coal dust from coal-fired plants, oils, and detergents.
V-50
-------
DRAFT
Table V-11 . RAW WASTE FLOWS AND LOADINGS - ASH HANDLING
PLANT NO.
WASTEWATER SOURCE
FLOW
PARAMETER
BOD,
0
Bromide (Bromate)
COD
Chromi urn
Chromi um+6
Copper
Cyanide (Total )
Iron
Nickel
Oil and Grease
Phosphate (Total)
Total Dissolved
Solids
Total Suspended
Solids
Total Solids
Surfactants
Zinc
6293
Ash Transport
Bl owdown
L/Day
2725?
mg/1
3.0
1235.0
0.37
0.030
0.16
0.005
76.0
0.24
1.0
3.4
388.0
1144.0
1532^0
0.55
L/MWH
113.55
g/MWH
0.34
140.23
0.04
0.003
0.018
0.0005
8.62
0.03
0.38
44.05
129.90
173.95
0.06
6387
Ash Transport
Bl owdown
L/Day
45420.0
mg/1
1 .2
290.0
0.12
0.009
0.20
0.112
6.2
0.03
1 .0
0.02
1894.0
1651 .0
3545.0
0.08
L/MWH
126.16
g/MWH
0.15
36.58
0.015
0.001
0.025
0.014
0.78
0.003
238.95
208.30
447.26
0.01
V-51
-------
DRAFT
Table y-12 . EFFLUENT FLOWS AND LOADINGS - ASH HANDLING
PLANT NO.
WASTEWATER SOURCE
FLOW
PARAMETER
BOD5
Bromide (Bromate)
COD
Chromi urn
Chromi um+ 6
Copper
Cyanide (Total )
I ron
Ni ckel
Oil and Grease
Phosphate (Total)
Total Dissolved Solids
Total Suspended Solids
Total Solids
Surfactants
Zinc
6387
Settled ash transport
condensate
L/Day
45420.0
mg/1
1.0
43.1
0.02
0.011
0.2
0.012
0.33
0.03
1.0
0.02
2980.0
70.0
3050.0
0.02
L/MWH
126.16
g/MWH
5.43
0.001
0.002
0.001
0.04
375.97
8.83
384.80
0.002
V-52
-------
DRAFT
Coal Pj1e. The storage of large quantities of coal
is necessary for coal-fired plants to insure continuous
operation and to simplify delivery by the supplier. A
90-day supply is normally maintained. Coal storage piles
are of two types: active and storage. Active piles are
used continuously and are subject to infiltration by
rainwater. Storage piles are used for the long-term
storage of coal, and are usually protected from rainfall
with some sort of seal, which can be either a layer of
asphalt or a layer of fine coal dust covered with lump
coal .
Waste discharges from coal storage piles are the product
of drainage from rainfall. This drainage can be either
acidic or alkaline. Acid drainage is the result of the
reaction of pyrite (FeS2j with water and oxygen, which
produces iron sulfate and sulfuric acid. This type of
drainage is highly acidic, has a low pH, and contains a
large amount of ferrous iron and some aluminum. Alkaline
drainage occurs when acid drainage is neutralized by
alkaline material present in the coal, or when the coal
has a low pyrite content. Alkaline drainage is characterized
by a pH of 6.5 to 7.5 or greater, little acidity, and
significant concentrations of ferrous iron. If the ferrous
iron concentration is high enough, the iron may precipitate
upon oxidation and hydrolysis.
Drainage from coal piles may contain in addition to the
aforementioned constituents, high concentrations of
dissolved solids and significant amounts of copper, zinc,
and manganese. Other materials may also be present that
are the result of the reaction of sulfuric acid with
minerals and organic compounds present in the coal.
Raw Waste Load
Coal Pile. Almost all of the plants that were visited
allowed coal pile drainage to drain to either the surface
water, storm sewers, or nearby land. An exception was
plant No. 9163, which stored all of its coal under roof,
thus eliminating any drainage problems.
V-53
-------
DRAFT
General chemical characteristics of coal pile drainage
were discussed under the previous heading. Reference 16
lists ranges for some of the elements present in coal
pile drainage, which are shown below:
Element Concentration Range, mg/1
Copper 1-4
Iron 0.1-5
Zinc 1-15
F1oor and Yard Drains. Drainage from floor and yard drains
in most cases can be assumed to be a negligible waste source.
Many plants exercise meticulous care,to prevent oil leaks
and spills from reaching floor drains by using drip pans and
oil absorbing materials. Some plants particularly those in,
open areas or in dry regions, have no need for yard drains
and have no drains installed.
Reference 16 list characteristics of wastes from yard and .
floor drains, which are summarized below:
Parameter Concentration Range (mq/1)
BOD 2-4
TSS 0-5
pH Low-Neutral
Surfactants Present
Chromium 0-20
Lead Present
Phosphorous 0-10
Oil and Grease Present
Wastewater Treatment
None of the plants that were visited used any type of
coal pile drainage treatment system.
One plant No. 7116 discharged floor drainage (along with other
wastes) to a settling tank before discharge to a POTW.
Other plants discharged floor and yard drainage without
treatment either directly to surface water or to a POTW.
Eff1uent Waste Loads
Information was not available on treated wastewater before
discharge to the POTW.
V-54
-------
DRAFT
AIR POLLUTION CONTROL EQUIPMENT
Liquid waste disposal problems associated with air pollution
control equipment are mainly limited to systems for the
control of 502^. Control systems for SO^ can be further
divided into "throwaway" and "recovery" processes. Throwaway
processes produce a sludge or cake that must be disposed
of. Recovery processes produce either elemental sulfur,
sulfuric acid, or gypsum, which are marketable and have no
disposal problems. The following discussion will be limited
to a throwaway process.
The greatest number of existing flue gas desulfurization
systems (including recovery and throwaway) use tail-end
scrubbing with lime and/or limestone. Those scrubbing systems,
installed after the boiler, remove particulates as well as
sulfur dioxide by reacting the flue gas with slurries of
lime or limestone forming calcium sulfates and sulfites.
The calcium sulfate/sulfite sludge is usually piped to
large settling ponds.
A small number of existing throwaway systems are of the
double-alkali type. In these systems, sodium or
ammonium sulfates and sulfites are used as a scrubbing
solution. After contacting the flue gas, the scrubbing
solution is reacted with limestone or lime to precipitate
calcium sulfite and sulfate and regenerate the solution
for recirculation to the scrubber. Scrubber wastes consist
of a dry filter cake.
Figure V-17 shows a flow diagram for an air pollution
control scrubbing system.
Water Use
None of the twenty-two plants visited in the study used
water to control S0_x emissions. This can be accounted for by the
fact that the majority of the plants burned low sulfur
(1 percent) coal or oil thereby eliminating the need for
air pollution control devices.
Raw Waste Load
None of the utilities visited had flue gas desulfurization
equipment. Since the wastes from these systems are mostly
in the form of sludges, which are disposed of on land, no
problems with waste discharges to POTW's are anticipated.
V-55
-------
DRAFT
_STACK GASES
STEAM TO TURBINES
COAL
BOILER
I FLUE GASES <
INLET
SCRUBHER LIQUOR
FIGURE V-17. Flow Diagram For Air Pollution Control
Scrubbing System (Ref. 14)
V-56
-------
DRAFT
Wastewater Treatment
None of the plants discharged SOx^ removal wastewaters to
the POTW.
Effluent Waste Load
Information was not available on treated wastewater before
discharge to the POTW.
MISCELLANEOUS HASTE STREAMS
Sanitary Hastes. Sanitary wastes from steam-electric plants
are similar to municipal domestic wastes with the absence
of laundry or kitchen wastes. The volume of waste flow is
dependent upon the number of employees.
Plant Laboratory Hastes. Many steam-electric plants have
laboratories for the chemical analysis of various process
streams within the plant. Depending on the analyses performed,
the waste from this source will contain a large variety
of chemicals, albeit in small amounts.
Intake Screen Backwash. Power plants that withdraw cooling
water from a natural body, such as a lake or river, use
traveling screens to prevent debris from entering the intake
system. Occasionally the debris from these screens is
collected, and the screens are washed with hoses.
Supplementing Cool ing Hater Systems. These cooling systems
are generally maintained for such uses as bearing and gland
cooling for pumps and fans. The systems may be once-
through or recirculating. Chemicals are not used in once-
through systems, except for occasional shock chlorination.
Recirculating systems use water of high purity, supplemented
by pretreated makeup water. Chromates, borates, and nitrates
are used in recirculating systems to prevent scale formation.
Construction Activity. The construction of buildings and
equipment adjacent to power plants can cause the presence
of additional amounts of suspended solids and turbidity
in the storm-water runoff due to the erosion of soil
disturbed by the construction activity.
V-57
-------
DRAFT
Hater Use
Housekeeping. Housekeeping water usage, which includes floor
washing and sanitary water (bathrooms, sinks, etc.), amounts
to less than one percent of the total. Only two plants of the
twenty-two in the study had any substantial floor wash water
usage these being plant No. 6421 with 13.08 liters per MWH
and plant No. 6294 with 1.71 liters per MWH. The following
table lists the water for sanitary purposes.
Plant No. Water Usage. Liters/MwH
9600 1.05
9369 7.96
8816 2.74
9585 6.23
9163 4.29
6387 6.73
8356 26.12
6293 4.73
8392 5.03
8875 0.4
7968 11.55
6421 261.54
6294 38.15
Miscellaneous Cooli ng. Miscellaneous cooling needs include
bearing cooling water, cooling of compressors, and other
extraneous equipment cooling needs. Water usage varied for
six plants from a low of 1.59 liters per MWH for plant No.
9396 to a high of 1.45xl04_ for plant No. 8356. Using the
least squares analysis method for the normalized data, a
coefficient of determination of 0.945 was calculated
indicating that approximately 94 percent of the data
variance could be accounted for by the least squares
straight line.
V-58
-------
DRAFT
Raw Waste Load
Sanitary Hastes. Reference 14 states that the per capita
sanitary waste load is generally 25-35 gal/day (94.5-132
liters/day) from steam-electric power plant. The reference
also lists the number of employees per MW that may be
expected to be found at typical power plants:
operational personnel: 1 per 20-40
maintenance personnel: 1 per 10-15
administrative personnel: 1 per 15-25
The flow, BOD^, and suspended solids per capita load can be
estimated by the following (14):
Flow BODS TSS
Office-Administrative 0.95 cu 30£ 70(j_
(per capita) m/day (0.0715) (0.15 lb)
(25 gpd)
Plant (per capita) 0.133 cu 40£ 85^
m/day (0.09 lb) (0.19 lb)
(35 gpd)
Plant Laboratory Hastes. The volume of wastes from in-plant
laboratory can be assumed to be negligible. Reference 14
suggests that if a toxic materials problem is found to
originate from a laboratory drain, it may be appropriate to
either: (1) change the test procedure, (2) contain the waste
for separate treatment, or (3) remove the waste from the site
Supplementary Cool ing Water Systems. Wastes are discharged
from recirculating cooling systems during blowdown, which
may typically be twenty liters per day with a settleable
solids content of 1-2 ppm (14). Additional wastes are
discharged during drainage and cleaning operations, which
are infrequent.
Plants which use once-through systems may discharge the
effluent from the entire system to a POTW. This waste
stream will probably contain chlorine, and the stream is
usually of significant volume.
Construction Activity and Intake Screen Backwash. The
nature and duration of these wastes do not contribute
significantly to the total waste load.
V-59
-------
DRAFT
Wastewater Treatment
Sanitary Wastes. Sanitary wastes are generally discharged
directly to POTW's or septic tanks without treatment. An
exception is plant 7116, which pretreats sanitary wastes
(along with other wastes) in a settling tank before
discharge to a POTW.
Plant Laboratory Hastes. Most plants combine laboratory
drains with other sanitary plant plumbing, and discharge
the waste without pretreatment.
Supplementary Cooling Water Systems. Supplementary cooling
system wastes are usually discharged directly, although
one plant 7116, discharged the waste to a settling tank
before discharge to a POTW.
Construction Activity and Intake Screen Backwash. Most
plants do not treat these wastewaters. Intake screens are
generally backwashed into the water source.
Eff1uent Haste Loads.
Information is not available on treated effluent from
miscellaneous waste streams.
THE POTH PROCESS
Preliminary Physical Treatment
Most POTW's employ initial physical treatment of wastewater
for the removal of course materials, settleable solids,
grease, and floating material.
B a r Racks and Commi nutors. These devices are used as the
first step in wastewater treatment to remove large solid
materials. Bar racks consist of large, parallel steel
bars placed perpendicular to the flow of wastewater. The
bars trap and retain large solids, which are removed
mechanically by a series of vertically-moving rakes
connected to a motor-driven, endless chain belt. The
solids are scraped off the racks with large mechanical
arms, and may then either be collected for land disposal
or ground in disintegrators and returned to the flow.
Smaller POTW's may use comminutors, which are motor-driven
cutting devices partially submerged in a narrow channel,
to grind up large materials as they pass through.
V-60
-------
DRAFT
Grit Chambers. Grit chambers are usually found in larger
POTW's. They are generally located after bar racks, and are
designed to remove sand, cinders, or other heavy particles
that have high settling velocities. Grit chambers may be
of two types: horizontal-flow, and aerated. Horizontal-f1ow
grit chambers consist simply of a channel designed to
maintain a constant flow velocity regardless of the volume
of water passing through the channel. The flow velocity
is lowered sufficiently over that of the influent wastewater
to allow grit to settle to the bottom. Removal of the grit
may be done either mechanically or by hand.
Aerated grit chambers consist of a spiral-flow aeration tank.
The velocity of flow in aerated chambers is determined by
the volume of the tank and the quantity of air that is
supplied. Aerated grit chambers are always cleaned
mechanically.
Primary Sedimentation. Primary sedimentation is used after
preliminary removal of solids in racks and grit chambers
and prior to biological treatment. The purpose of primary
sedimentation, when used prior to biological treatment, is
to reduce the suspended solids and BOD load on the biological
treatment units. This is accomplished in large, rectangular
(or circular) sedimentation tanks that provide a sufficient
detention time for the removal of settleable solids and
floating material. Grease and other floating materials are
skimmed off from the surface with large rotating arms.
Solids that settle to the bottom of the tank (known as
primary sludge) are mechanically pushed into a hopper,
where they are collected for further treatment. Primary
sedimentation tanks, if designed properly and operated
correctly, will remove 50 to 65 percent of the suspended
solids in the influent wastewater and from 25 to 40 percent
of the BOD. If primary sedimentation is used as the only
means of treatment, the effluent is usually chlorinated to
remove pathogens.
Secondary Biological Treatment
Secondary biological treatment is used to convert soluble
and colloidal organic material into settleable flocculant
material that can be removed in sedimentation tanks. Two
types of biological treatment processes are most often
employed: (1) the activated-sludge process, and (2)
trickling filters.
V-61
-------
DRAFT
Activated-Sludge Process. The activated-sludge process
consists of an aerated basin containing a large mass of
microorganisms and flocculated solids, known as the mixed
liquor, followed by a sedimentation tank in which the
solids are removed. The sedimentation tank may either be
part of the same structure as the aeration basin, or it may
be completely separate. Part of the solids that settle
in the sedimentation tank (the secondary sludge) is removed
for further treatment, and part is recycled to the aeration
basin. The effluent from the sedimentation tanks is usually
chlorinated.
Bacteria make up the largest portion of the microorganisms
present in the activated sludge, and are responsible for the
majority of the waste stabilization that occurs. The
mechanisms by which bacteria stabilize a waste is twofold,
consisting of: (1) consumption of organic matter, which is
partially oxidized to lower energy compounds and partially
converted to new cellular material, and (2) the production
of polymers and slime that bind bacterial cells and other
suspended material into flocculant particles that can be
removed by sedimentation. Other microorganisms may also be
present, such as protoza, which consume bacteria that have
not flocculated, and rotifers, which consume small floe
particles that have not settled. Activated sludge systems
are usually from 55-^95 percent efficient in removing BOD,
and from 55-95 percent efficient in removing suspended
solids (Figure V-18).
Trickling Filters. Trickling filters consist of a bed of
rocks or plastic material that support a growth of microbial
material (slime layer). Wastewater is sprayed over the
top of the bed, which is circular, with a rotating
distributor. As the waste percolates through the bed,
organic material is adsorbed onto the slime layer. At
periodic intervals, partly because of the increase in
thickness of the slime layer, the microorganisms in the
layer lose their ability to cling to the surface of the
filter media and the slime layer is washed off by the
wastewater (a process called "sloughing"). (Figure V-18).
V-62
-------
DRAFT
Wast
e Sludge
Inf1uent
e
Activated Sludge Process
Trickling
Filter
SIudge
Return
Fi nal
Sedimentati on
Effluent
SIudge
Inf1uen
Wet
Well
Sludge Return Line ,
Effluent
Trickling Filter Process
FIGURE V-18. Flow Diagram of Secondary Treatment Methods
V-63
-------
DRAFT
Trickling filters are divided into two categories: low-rate
and high-rate, based on organic loading rates. Both types
of filters achieve equivalent BOD removal efficiencies, but
high-rate filters are advantageous since they have a higher
rate of BOD removal (and thus can accept higher influent
flow rates) than low-rate filters. This is achieved by
recycling a portion of the influent to return viable
organisms back to the filters. Low-rate filters have no
recycle. Both types of filters are followed by a settling
tank (clarifier) to remove suspended solids produced during
sloughing. The effluent from the settling tank is generally
chlorinated. Trickling filters are from 50-95 percent
efficient in the removal of BOD, and 30-92 percent efficient
in the removal of suspended solids.
Figure V-19 shows a wastewater treatment process diagram
utilizing activated sludge or trickling filters.
T-reatment and Pi sposal of SI udge.
The problem of disposing of sludges produced during primary
and secondary treatment is one of the most complex tasks
faced by the engineer. Techniques for dealing with sludges
are varied, but most involve: (1) digestion, followed by (2)
conditioning, and (3) dewatering and drying (Figure V-20).
Digestion is a biological process for reducing the volume of
sludge. Two types of digesters are in use: anaerobic,
and aerobic. Anaerobic digesters are closed, heated tanks
in which various microorganisms decompose organic and/or
inorganic matter without the presence of oxygen, forming
methane, carbon dioxide, and sludge solids. The methane
that is involved during the process can be used as a fuel,
and its rate of production is one of the best measures of
the satisfactory operation of the digester. Chemical
conditioning, followed by centrifugation or vacuum filtration,
is usually used to treat sludge solids during anaerobic
digestion. Chemical conditioning involves the use of ferric
chloride, lime, alum, or organic polymers to coagulate the
solids and release absorbed water. Centrifugation and vacuum
filtration are physical operations that are used to remove
water from the sludge solids prior to final disposal.
Aerobic digestion is much like the activated sludge process,
involving consumption of organic compounds in sewage by
an aerated mass of microorganisms. As the supply of organic
material run out, the microorganisms begin to consume their
own protoplasm. Sludge solids from aerobic digesters are
stable and are more easily dewatered by vacuum filtration or
drying on sand beds.
V-64
-------
Influent
:reenings
1
Grit
t
Sludge
t
Waste sludge
Return sludge |
>
— i — j^.
1
r
Effluen
Bar racks
Primary Aeration tank
Grit chambers sedimentation
Acitvated Sludge
Treatment Scheme
Settling tank Chlorine
contact chamber
Screenings
en
en
Inf1uent
Bar racks
Grit
SIudge
Waste sludge
Cl,
t J
«^
L t
>
Return effluent jf,
r
1
>
r
^_
Effluent
frit rh.mhPr, p.ri"mary Trickling Settling tank (lhl°Hnue K
Grit chambers sedimentation ,.,. contact chamber
filters
Trickling Filter
Treatment Scheme
FIGURE V-19. Wastewater Treatment Flow Diagram
-------
Anaerobic sludge
digestion
Chemical conditioning
Centrifuge
Sludge from sedimen-
tation tanks
Digested
siudge
Centrat
Supernatant
Sludge Disposal Scheme
Dewatered sludge to
ultimate disposal o
FIGURE V-20. Flow Diagram for Sludge Treatment
-------
DRAFT
Tertiary Treatment
Many chemical constituents present in wastewater, especially
nitrogen and phosphorus, are slightly affected by conventional
primary and secondary treatment. Since these chemicals can
have adverse effects on the receiving water by promoting the
growth of algae and other unwanted aquatic vegetation, their
removal is desirable in some cases. Although tertiary
treatment processes are still uncommon, their use is receiving
considerable attention. Two processes, nitrification for
the removal of nitrogen, and precipitation for the removal
of phosphorus, will be discussed.
Nitrification-Denitrification. This process appears to be
the most promising for the removal of nitrogen. The technique
involves aerobic conversion of ammonia to the nitrate form
(nitrification), followed by anaerobic conversion of the
nitrates to nitrogen gas (denitrification). Both steps
involve the production of specialized groups of bacteria,
and require detailed attention to operating and environmental
conditions. Denitrification requires the addition of a
supplemental carbon source for successful operation. Methanol
is usually used. Nitrification-denitrificat ion is from
60-65 percent efficient in removing nitrates. Figure V-21
shows a flow diagram of the nitrification-denitrification
process.
Chemical Precipitation. Precipitation of phosphorus can be
achieved by the addition of chemicals such as lime, alum,
and ferric chloride, or sulfate. These chemicals are usually
added to the raw wastewater and the phosphorus is
precipitated during primary sedimentation, however, these
chemicals can also be added in the activated-sludge aeration
tank or to the secondary clarifier. Removal of phosphates
by precipitation in primary sedimentation tanks is from 90-
95 percent efficient.
EFFECTS 0£ STEAM-ELECTRIC WASTEWATERS ON. POTW ' S
The wastewaters discharged by steam-electric plants vary
greatly in flow and waste loadings. For the twenty-two
plants visited during this study, the steam-electric
wastewaters represented less than five percent of the
total POTW influent. Table V-13 lists the combined discharge
rate for each steam-electric plant along with the associated
POTW influent flow and treatment scheme.
V-67
-------
Waste sludge
Waste sludge
pH adjustment
Secondary
eff1uent
Organic
Plug flow reactor
Sludge return
pH adjustment
Chemical
addition
Final effluent
Settling tank
PIug f1ow reactor
Sludge return
Sett!ing tank
CO
o
73
Nitrification
Denitrification
Nitrogen Removal
Scheme
FIGURE V-21. Flow Diagram of Nitrification - Denitrification Process
-------
Table V-13. POWER PLANT AND POTW FLOWS
Plant
No
9600
9650
9369
9371
7485
8816
9585
7116
8696
8135
9163
6387
8392
6293
7308
8875
7968
6421
6214
6294
Combined Flow
to POTW. gpd
(1/d)
No data (plant has been
using POTW for only one
year)
100,00
(378,000)
2,350
(8,880)
15,000
(56,700)
1 ,580
(5,970)
2,000
(7,560)
600
(2,270)
Data Incomplete
173,000
(654,000)
150,400
46,900
(177,000)
9,500
(35,900)
126,000
(476,000)
9,100
(34,400)
902,000
(3.41 x 106)
423,000
(1 .60 x 106)
Data Incomplete
26,000
(98,300)
No data - operates only
50 hours/yr
35,000
(132,000)
POTW Average
Flow, gpd
(1/d)
97.5 x 106
(369 x 106)
2.4 x 106
(9.1 x 1Q6)
10.0 x 106
(22.7 x 106)
300,000
(1.1 x 106)
350 x 106
(1,320 x 106)
4.5 x 106
(17.0 x 106)
3.5 x lof
(13.2 x 106)
350 x 106
(1,320 x 106)
% of POTW
Flow
0.10
0.098
0.15
0.50
0.01
0.01
...
0.049
POTW
Treatment Scheme
Activated sludge,
anaerobic digestion
Rotating biological
surfaces; anaerobic
digestion
Activated sludge,
aerobic digestion
Activated sludge,
aerobic digestion
Activated sludge,
anaerobic digestion
Oxidation pond
Activated sludge
Activated sludge,
anaerobic digestion
No POTW at present - to be hooked up
to West Palm Beach POTW in 1978 - Sewers
presently run to ocean
10 x 106
(38 x 1C6)
220,000
(832,000)
1 .5 x 106
(5.7 x 106)
2 x 106
(7.6 x 106)
315 x 106
(1 ,190 x 106)
31 .1 x 106
(120 x 106)
...
1.4 x 106
(5.3 x 106)
1 .4 x lo£
(5.3 x 106)
1 .4 x 106
(5.3 x 106)
0.47
4.3
8.4
0.46
0.29
1 .4
1.9
...
2.5
Trickling filters;
anaerobic digestion
Trickling filters;
no digestion
Activated sludge,
aerobic digestion
Activated sludge
trickl ing f i 1 ters
anaerobic digesters
Primary treatment only
secondary treatment
facilities being built
Activated sludge,
trickling filters,
anaerobic digestion
Activated sludge
Activated sludge
Activated sludge
V-69
-------
DRAFT
Rajv Haste Load
Waste loads in the combined discharge are affected by any
occurrence in the steam-electric which use and discharge
water. The waterborne waste loads in the combined discharge
for six (6) plants are shown in Table V-14 The major
pollutants are chemical oxygen demand and dissolved and
total solids, with lesser values of iron, nickel, phosphates
and total and hexavalent chromium.
V-70
-------
Table V-14. RAW WASTE FLOWS AND LOADINGS - COMBINED DISCHARGE TO POTW
PLANT NO
WASTEHATER SOURCE
FLOW
PARAMETER
soc5
Brcmide (Bromate)
COC
Chromi um
Chromi um
Copper
Cysnide (Total )
Iron
Nickel
Oil and Grease
Phosphate (Total)
Total Dissolved
Solids
Total Suspended
Total Solids
Surfactants
Zi nc
6387
Combined Discharge
L/Day L/MWH
518.0QQ 1870
mg/1 g/MWH
8.4 16
49.0 91.6
<0.02 Uncertain
0.006 0.01
0.02 0.04
0.006 0.01
0.64 1.2
<0.03 Uncertain
<1.0 Uncertain
1454 2719
241 451
1695 3170
0.024 0.04
0.07 0.1
8392
Combined Discharge
L/Day L/KWH
233.000 755
mg/1 g/MWH
20 15
11.8 8.91
8.1 6.1
8.0 6.0
0.04 0.03
<0.005 <0.005
0.71 0.54
<0.03 <0.03
1.2 0.91
16 12
<1.0 <1.0
16 12
2.6 2.0
7308
Combined Discharge
L/Dav L/MWH
?.qsn.noo 229
mg/1 g/MWH
6.0 1.4
50 11
1.76 0.403
0.66 0.15
0.45 0.10
<0.0005 <0.005
14.7 3.37
12 2-7
5.8 1.3
2080 476
226 51.7
2306 520
1.47 0.337
8696*
Combined Discharge
L/Day L/MWH
272.000 3U
ng/1 g/X'.
-------
DRAFT
WASTE COMPARISON
Effluent data gathered from the eight (8) plants sampled
during this study were compared with similar data gathered
in support of the "Development Document for Effluent
Limitations Guidelines and Standards of Performance for the
Steam Electric Power Generating Point Source Category" (14)
Comparison was made to identify similarities and differences
in the quality and quantity of aqueous plant effluents.
Waste streams for which data was available for comparison
include:
• Recirculating Condenser Cooling Water
t Water Treatment Wastes
• Boiler Slowdown
t Ash Handling Wastes
These data may be found in Table V-15.
Recirculating Condenser Cool ing Water
Flow data in this study tended to coincide with lower flows
reported in the development document (14) and were similar.
Concentrations of BOD, phosphate, dissolved solids,
suspended solids, total solids, and zinc observed in this
study were within the range of those reported in the
Development Document. Concentrations of chromium, copper,
iron and nickel observed in this study tended to be lower
than those reported in the development document. This
difference is probably due to lower influent loadings of
these heavy metal components. Metals such as iron, and
copper tend to be removed during municipal water treatment.
Most of the plants contacted in this study used municipal
water as raw feed water for all purposes.
Water Treatment Wastes
Flows and parameter concentrations of wastes observed
in this study were within the range of those reported in
the development document.
V-72
-------
DRAFT
Boiler Slowdown
Flow data for boiler blowdown observed in this study was
within the range of those reported in the development
document. Concentrations of all parameters observed in this
study were similar to those reported in the development
document with the exception of BOD, and zinc. BOD values
observed in this study tended to be higher than those
reported in the development document. Observed zinc values
tended to be lower. BOD difference in this low range are not
significant as the test method is not precise in this range.
Zinc concentrations are understandably lower for all
discharges observed in this study due to use of municipal
water as influent water.
Ash Hand!ing Hastes
Wastewater flows of ash handling wastes observed in this
study were within the range of those reported in the
development document (14). Concentrations of parameters
observed in this study were within the range of those
reported in the development document, with the exception of
phosphate. Phosphate concentrations observed in this study
were higher than those reported in the development document.
Higher maximum phosphate concentrations are probably due to
the variable nature of coal impurities.
Summary
Overall, values, of effluent flows and parameter concentrations
observed in this study were similar to those reported in
data referenced in the development document (14). The few
parameters in this study that lay outside the range of
development document data tended to be lower, reflecting
the higher quality of the municipal water used as influent
water for the stations contacted in this study. Therefore,
it may be concluded that the stations affected by the
results of this study are not different from those (direct
dischargers) affected by the development document (14).
V-73
-------
Table V-15
COMPARISON OF PARAMETER VALUES
PLANT RAM WASTES
^ ^ WASTE
^^^STREAM
PARAMETER^^^^^
FLOW (L/DAY) H^
PARAMETER. MG/L
BOD L?
HI
COD L?
HI
CHROMIUM h?
HI
COPPER h?
HI
IRON f;9'
HI
NICKEL ^-
Hl
PHOSPHATE \£—
Hi
IDS LO
HI
TSS L0
HI
TS h?
HI
ziNr ^
iiwu HI
RECIRCULATING
CONDENSER .
COOLING WATER
THIS
STUDY
53,600
238,400
1.4
22
10
102
0.02
5
0.02
0.7
0.5
1.6
0.03
0.04
0.1
3
886
5,111
3
59
889
5,170
0.1
1.5
REF.14
109,000
27,258,000
2
18
36
436
10
120
63
1,740
60
1 ,160
80
150
0.1
18
150
32,700
2
220
750
32,700
0.3
3,000
WATER TREATMENT
WASTES
THIS
STUDY
4,277
40,900
1.0
48
2.0
76
0.02
0.1
0.02
2.6
0.02
10.4
0.03
0.25
0.05
14.0
0.16
23,000
1.0
1,780
0.16
1 ,968
0.02
0.44
REF.14
150
136,000,000
0
344
0
440
0.05
2.168
0.006
3.09
0.015
37.5
0.007
0.56
0.1
87.2
2
35,235
0
300
15
36,237
0 I
4.5
BOILER SLOWDOWN
THIS
STUDY
5,715
17,030
10.8
11.7
2.0
157
.02
.02
.02
.19
.03
1.4
.03
.03
.05
19.8
118
1,405
2.7
31
125
1407.7
.01
.05
REF.14
4,530
4,233,000
0
6
0
784
0.001
1.5
0
0.3
0.03
0.3
0
0.13
0.01
29
5
26,006
0
300
5
26,077
0.1
1.2
ASH HANDLING
WASTES
THIS
STUDY
27,252
45,420
1.2
3.0
240
1,235
0.12
0.37
0.16
0.2
6.2
76.0
0.03
0.24
0.02
3.4
388
1,894
1,144
1,651
1,532
3,545
0.03
0.55
REF.14
18,170
98,436,000
0
30
2
306
0.045
40
.009
100
0.001
2,100
0.01
10
0
0.24
83
32,423
4
236
35
32,412
0
0.52
-------
DRAFT
SECTION VI
SELECTION OF POLLUTANT PARAMETERS
INTRODUCTION
Aqueous pollutants originating from steam electric power
generating facilities which are of potential harm to either
publicly-owned treatment works (POTW) or to receiving
waters at the point of discharge of the POTW are
identified in this section.
RATIONALE FOR THE SELECTION 0_F POLLUTANT PARAMETERS
Pollutants were selected based on their harmful effects on
treatment works. If the pollutant passes through typical
treatment works, it was selected on the basis of its
potential for harm to receiving waters. The following
factors were considered in this selection:
t Potential harm to POTW. The pollutant may
impair the activity of biological treatment
systems by either: (1) causing the death of
some or all of the microorganisms that are
essential to the operation of the POTW, or
(2) impairing the activity of these
microorganisms so that their waste-consuming
efficiency is lowered. Examples of treatment
units that may be adversely affected by
pollutants are: trickling filters, activated
sludge units, anaerobic digesters, and
nitrification units.
• Potenti al harm to the receiving water. If
the pollutant is not removed or is removed
inadequately by the POTW, it may be of
significant harm to the receiving water. In
this respect, the pollutant may cause damage
to the fish and plant life of the water, or
it may render the water unsuitable for use
for domestic, industrial, or recreational
purposes.
VI-1
-------
DRAFT
• Presence or absence in plant effluents
Parameters such as total suspended solids (TSS), biochemical
oxygen demand (BOD), and chemical oxygen demand (COD) that
are normally removed (to a given extent) by treatment plants
are also discussed. This discussion does not necessarily
indicate that these parameters are of harm to a POTW, but
only that they were part of routine analysis of effluent
samples.
A discussion of the effects of selected pollutants on
treatment plants is included in Appendix C. The following
discussion is primarily related to the effects of the
pollutants on receiving waters.
Properties ojF Selected Pollutant Parameters
Acidity and Alkalinity - £H. Although not a specific
pollutant, pH is related to the acidity or alkalinity of a
wastewater stream. It is not a linear or direct measure
of either, however, it may be properly used as a surrogate
to control both excess acidity and excess alkalinity in
water. The term pH is used to describe the hydrogen ion -
hydroxyl ion balance in water. Technically, pH is related
to the hydrogen ion concentration or activity present in a
given solution. pH numbers are the negative logarithm of
the hydrogen ion concentration. A pH of 7 indicates
neutrality or a balance between free hydrogen and free
hydroxyl ions. Solutions with a pH above 7 indicate that
the solution is alkaline, while a pH below 7 indicates
that the solution is acidic.
Knowledge of the pH of water or wastewater is useful in
determining necessary measures for corrosion control,
pollution control, and disinfection. Waters with a pH
below 6.0 are corrosive to water works structures,
distribution lines, and household plumbing fixtures such as
iron, copper, zinc, cadmium, and lead. Low pH waters not
only tend to dissolve metals from structures and fixtures
but also tend to redissolve or leach metals from sludges
and bottom sediments. The hydrogen ion concentration can
affect the "taste" of the water and at a low pH, water
tastes "sour."
VI-2
-------
DRAFT
Extremes of pH or rapid pH changes can exert stress
conditions or kill aquatic life outright. Even moderate
changes from "acceptable" criteria limits of pH are
deleterious to some species. The relative toxicity to
aquatic life of many materials is increased by changes in
the water pH. For example, metalocyanide complexes can
increase a thousand-fold in toxicity with a drop of 1.5 pH
units. Similarly, the toxicity of ammonia is a function of
pH. The bactericidal effect of chlorine in most cases is
less as the pH increases, and it is economically advantageous
to keep the pH close to 7.
Acidity. Acidity is defined as the quantitative ability of
a water to neutralize hydroxyl ions. It is usually expressed
as the calcium carbonate equivalent of the hydroxyl ions
neutralized. Acidity should not be confused with pH value.
Acidity is the quantity of hydrogen ions which may be
released to react with or neutralize hydroxyl ions while pH
is a measure of the free hydrogen ions in a solution at the
instant the pH measurement is made. A property of many
chemicals, called buffering, may hold hydrogen ions in
solution from being in the free state and being measured as
pH. The bond of most buffers is rather weak and hydrogen
ions tend to be released from the buffer as needed to
maintain a fixed pH value.
Highly acid waters are corrosive to metals, concrete, and
living organisms, exhibiting the pollutional characteristics
outlined above for low pH waters. Depending on buffering
capacity, water may have a higher total acidity at pH values
of 6.0 than other waters with a pH value of 4.0.
A1kalinity. Alkalinity is defined as the ability of a water
to neutralize hydrogen ions. It is usually expressed as the
calcium carbonate equivalent of the hydrogen ions neutralized
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Alkalinity is commonly caused by the presence of carbonates,
bicarbonates, hydroxides, and to a lesser extent by borates,
silicates, phophates, and organic substances. Because of
the nature of the chemicals causing alkalinity, and the
buffering capacity of carbon dioxide in water, very high
pH values are seldom found in natural waters.
Excess alkalinity, as exhibited in a high pH value, may
make water corrosive to certain metals, detrimental to most
natural organic materials, and toxic to living organisms.
Ammonia is more irritating at higher pH. The lacrimal fluid
of the human eye has a pH of approximately 7.0 and a deviation
of 0.1 pH unit from the norm may result in eye irritation
for the swimmer. Appreciable irritation will cause severe
pain.
Oi 1 and Grease
Because of widespread use, oil and grease occur often in
wastewater streams. These oily wastes may be classified
as fol1ows:
• Light Hydrocarbons. These include light fuels
such as gasoline, kerosene, and jet fuel, and
miscellaneous solvents used for industrial
processing, degreasing, or cleaning purposes.
The presence of these hydrocarbons may make the
removal of other heavier oily wastes more difficult.
• Heavy Hydrocarbons. Fuels, and Tars. These include
the crude oils, diesel oils, #6 fuel oil, residual
oils, slop oils, and in some cases, asphalt and
road tar.
• Lubricants and Cutting Fluids^ These generally
fall into two classes: non-emulsifiable oils
such as lubricating oils and greases, and
emulsifiable oils such as water soluble oils,
rolling oils, cutting oils, and drawing
compounds. Emulsifiable oils may contain fat
soap or various other additives.
t Vegetable and Animal Fats and Oils. These
originate primarily from processing of foods and
natural products.
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These compounds can settle or float and may exist as
solids or liquids depending upon factors such as method
of use, production process, and temperature of
wastewater.
Oil and grease even in small quantities cause troublesome
taste and odor problems. Scum lines from these agents are
formed on water treatment basin walls and other containers.
Fish and water fowl are adversely affected by oils in
their habitat. Oil emulsions may adhere to the gills of
fish causing suffocation, and the flesh of fish is tainted
when microorganisms that were exposed to waste oil are
eaten. Deposition of oil in the bottom sediments of water
can serve to inhibit normal benthic growth. Oil and grease
exhibit an oxygen demand.
Levels of oil and grease which are toxic to aquatic
organisms vary greatly, depending on the type and the
species susceptibility. However, it has been reported that
crude oil in concentrations as low as 0.3 mg/1 is extremely
toxic to fresh-water fish. It has been recommended that
public water supply sources be essentially free from oil
and grease.
Oil and grease in quantities of 100 1/sq km (10 gallons/sq
mile) show up as a sheen on the surface of a body of water.
The presence of oil slicks prevent the full aesthetic
enjoyment of water. The presence of oil in water can also
increase the toxicity of other substances being discharged
into the receiving bodies of water. Municipalities
frequently limit the quantity of oil and grease that can be
discharged to their wastewater treatment systems by
industry.
Chemical Oxygen Demand (COD) and Biochemi cal Oxygen
Demand (BOD)
The Chemical Oxygen Demand (COD) is a purely chemical
oxidation test devised as an alternate method of estimating
the total oxygen demand of a wastewater. Since the method
relies on the oxidation-reduction system of chemical analyses
rather than on biological factors, it is more precise,
accurate, and rapid than the Biochemical Oxygen Demand (BOD)
test. The COD test is widely used to estimate the total
oxygen demand (ultimate rather than 5-day BOD) to oxidize
the compounds in a wastewater. It is based on the fact that
organic compounds, with a few exceptions, can be oxidized
by strong chemical oxidizing agents under acid conditions
with the assistance of certain inorganic catalysts.
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The COD test measures the oxygen demand of compounds that
are biologically degradable and of many that are not.
Pollutants which are measured by the BODS test will be
measured by the COD test. In addition, pollutants which
are more resistant to biological oxidation will also be
measured as COD. COD is a more inclusive measure of oxygen
demand than is BOD5 and will result in higher oxygen demand
values than will the BOD5 test.
The compounds which are more resistant to biological
oxidation are becoming of greater and greater concern not
only because of their slow but continuing oxygen demand
on the resources of the receiving water, but also because
of their potential health effects on aquatic life and humans.
Many of these compounds result from industrial discharges
and some have been found to have carcinogenic, mutagenic,
and similar adverse effects, either singly or in combination.
Concern about these compounds has increased as a result of
demonstrations that their long life in receiving waters-
the result of a slow biochemical oxidation rate — allows
them to contaminate downstream water intakes. The commonly
used systems of water purification are not effective in
removing these types of materials and disinfection such as
chlorination may convert them into even more hazardous
materi als .
Thus the COD test measures organic matter which exerts an
oxygen demand and which may affect the health of the people.
It is a useful analytical tool for pollution control
activities. It provides a more rapid measurement of the
oxygen demand and an estimate of organic compounds which are
not measured in the BOD5 test.
BOD. Biochemical oxygen demand (BOD) is the quantity of
oxygen required for the biological and chemical oxidation of
waterborne substances under test conditions. Materials which
may contribute to the BOD include: carbonaceous organic
materials usable as a food source by aerobic organisms;
oxidizable nitrogen derived from nitrites, ammonia and
organic nitrogen compounds which serve as food for specific
bacteria; and certain chemically oxidizable materials such
as ferrous iron, sulfides, sulfite, etc. which will react
with dissolved oxygen or are metabolized by bacteria. In
most industrial and municipal wastewaters, the BOD derives
principally from organic materials and from ammonia (which
is itself derived from animal or vegetable matter).
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The BOD of a waste exerts an adverse effect upon the
dissolved oxygen resources of a body of water by reducing
the oxygen available to fish, plant life, and other
aquatic species. Conditions can be reached where all of
the dissolved oxygen in the water is utilized resulting
in anaerobic conditions and the production of undesirable
gases such as hydrogen sulfide and methane. The reduction
of dissolved oxygen can be detrimental to fish populations,
fish growth rate, and organisms used as fish food. A
total lack of oxygen due to the exertion of an excessive
BOD can result in the death of all aerobic aquatic
inhabitants in the affected area.
Water with a high BOD indicates the presence of decomposing
organic matter and associated increased bacterial
concentrations that degrade its quality and potential uses.
A by-product of high BOD concentrations can be increased
algal concentrations and blooms which result from
decomposition of the organic matter and which form the
basis of algal populations.
The BODS (5-day BOD) test is used widely to estimate the
pollutional strength of domestic and industrial wastes in
terms of the oxygen that they will require if discharged
into receiving streams. The test is an important one in
water pollution control activities. It is used for
pollution control regulatory activities, to evaluate the
design and efficiencies of wastewater treatment works, and
to indicate the state of purification or pollution of
receiving bodies of water.
Complete biochemical oxidation of a given waste may require
a period of incubation too long for practical analytical
test purposes. For this reason, the five-day period has been
accepted as standard, and the test results have been
designated as BODS. Specific chemical test methods are not
readily available for measuring the quantity of many
degradable substances and their reaction products. Reliance
in such cases is placed on the collective parameter, BODS,
which measures the weight of dissolved oxygen utilized by
microoganisms as they oxidize or transform the gross mixture
of chemical compounds in the wastewater. The compounds are
related to the period of incubation. The five-day BOD
normally measures only 60 to 80 percent of the carbonaceous
biochemical oxygen demand of the sample, and for many
purposes this is a reasonable parameter. Additionally, it
can be used to estimate the gross quantity of oxidizable
organic matter.
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The BOD5 test is essentially a bioassay procedure which
provides an estimate of the oxygen consumed by microorganisms
utilizing the degradable matter present in a waste under
conditions that are representative of those that are likely
to occur in nature. Standard conditions of time, temperature
suggested microbial seed, and dilution water for the wastes
have been defined and are incorporated in the standard
analytical procedure. Through the use of this procedure, the
oxygen demand of diverse wastes can be compared and evaluated
for pollution potential and to some extent for treatability
by biological treatment processes.
Because the BOD test is a bioassay procedure, it is important
that the environmental conditions of the test be suitable
for the microorganisms to function in an uninhibited manner
at all times. This means that toxic substances must be
absent and that the necessary nutrients, such as nitrogen,
phosphorous, and trace elements, must be present.
Total Suspended Solids (TSS)
Suspended solids include both organic and inorganic materials
The inorganic compounds include sand, silt, and clay. The
organic fraction includes such materials as grease, oil,
tar, and animal and vegetable waste products. These solids
may settle out rapidly and bottom deposits are often a
mixture of both organic and inorganic solids. Solids may be
suspended in water for a time, and then settle to the bed of
the stream or lake. These solids discharged with man's
wastes may be inert, slowly biodegradable materials, or
rapidly decomposable substances. While in suspension, they
increase the turbidity of the water, reduce light penetration
and impair the photosynthetic activity of aquatic plants.
Suspended solids in water interfere with many industrial
processes, cause foaming in boilers, and incrustations on
equipment exposed to such water, especially as the
temperature rises. They are undesirable in process water
used in the manufacture of steel, in the textile industry,
in laundries, in dyeing, and in cooling systems.
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Solids in suspension are aesthetically displeasing when
they settle to form sludge deposits on the stream or lake
bed. They are often damaging to the life in water. Solids,
when transformed to sludge deposits, may do a variety of
damaging things, including blanketing the stream or lake
bed and thereby destroying the living spaces for those
benthic organisms that would otherwise occupy the habitat.
When of an organic nature, solids use a portion of all of
the dissolved oxygen available in the area. Organic
materials also serve as a food source for sludgeworms and
associated organisms.
Disregarding any toxic effect attributable to substances
leached out by water, suspended solids may kill fish and
shellfish by causing abrasive injuries and by clogging the
gills and respiratory passages of various aquatic fauna.
Indirectly, suspended solids are inimical to aquatic life
because they screen out light, and they promote and
maintain the development of noxious conditions through
oxygen depletion. This results in the killing of fish and
fish food organisms. Suspended solids also reduce the
recreational value of the water.
Turbidity. Turbidity of water is related to the amount of
suspended and colloidal matter contained in the water. It
affects the clearness and penetration of light. The degree
of turbidity is only an expression of one effect of suspended
solids upon the character of the water. Turbidity can reduce
the effectiveness of chlorination and can result in
difficulties in meeting BOD and suspended solids limitations.
Turbidity is an indirect measure of suspended solids.
Chromi urn (Cr)
Chromium is an elemental metal usually found as a chromite
(FeCr204). The metal is normally processed by reducing the
oxide with aluminum.
Chromium and its compounds are used extensively throughout
industry. It is used to harden steel and as an ingredient
in other useful alloys. Chromium is also used in the
electroplating industry as an ornamental and corrosion
resistant plating on steel and can be used in pigments and
as a pickling acid (chromic acid).
The two most prevalent chromium forms found in industry
wastewaters are hexavalent and trivalent chromium. Chromic
acid used in industry is a hexavalent chromium compound
which is partially reduced to the trivalent from during
use. Chromium can exist as either trivalent or hexavalent
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compounds in raw waste streams. Hexavalent chromium
treatment involves reduction to the trivalent form prior to
removal of chromium from the waste stream as a hydroxide
precipitate.
Chromium, in its various valence states, is hazardous to
man. It can produce lung tumors when inhaled and induces
skin sensitizations. Large doses of chromates have
corrosive effects on the intestinal tract and can cause
inflammation of the kidneys. Levels of chromate ions that
have no effect on man appear to be so low as to prohibit
determination to date. The recommendation for public
water supplies is that such supplies contain no more than
0.05 rng/1 total chromium.
The toxicity of chromium salts to fish and other aquatic
life varies widely with the species, temperature, pH,
valence of the chromium, and synergistic or antagonistic
effects, especially that of hard water. Studies have shown
that trivalent chromium is more toxic to fish of some types
than hexavalent chromium. Other studies have shown opposite
effects. Fish food organisms and other lower forms of
aquatic life are extremely sensitive to chromium and it
also inhibits the growth of algae. Therefore, both
hexavalent and trivalent chromium must be considered
harmful to particular fish or organisms.
Copper is an elemental metal that is sometimes found free
in nature and is found in many minerals such as cuprite,
malachite, azurite, chalcopyrite, and bornite. Copper is
obtained from these ores by smelting, leaching, and
electrolysis. Significant industrial uses are in the
plating, electrical, plumbing, and heating equipment
industries. Copper is also commonly used with other
minerals as an insecticide and fungicide.
Traces of copper are found in all forms of plant and animal
life, and it is an essential trace element for nutrition.
Copper is not considered to be a cumulative systemic
poison for humans as it is readily excreted by the body, but
it can cause symptoms of gastroenteritis, with nausea and
intestinal irritations, at relatively low dosages. The
limiting factor in domestic water supplies is taste.
Threshold concentrations for taste have been generally
reported in the range of 1.0 to 2.0 mg/1 of copper while
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concentrations of 5 to 7.5 mg/1 have made water completely
undrinkable. It has been recommended that the copper in
public water supply sources not exceed 1 mg/1.
Copper salts cause undesirable color reactions in the food
industry and cause pitting when deposited on some other
metals such as aluminum and galvanized steel. The textile
industry is affected when copper salts are present in
water used for processing of fabrics. Irrigation waters
containing more than minute quantities of copper can be
detrimental to certain crops. The toxicity of copper to
aquatic organisms varies significantly, not only with the
species, but also with the physical and chemical
characteristics of the water, including temperature,
hardness, turbidity, and carbon dioxide content. In hard
water, the toxicity of copper salts may be reduced by the
precipitation of copper carbonate or other insoluble
compounds. The sulfates of copper and zinc, and of copper
and cadmium are synergistic in their toxic effect on fish.
Copper concentrations less than 1 mg/1 have been reported to
be toxic, particularly in soft water, to many kinds of fish,
crustaceans, molluscs, insects, phytoplankton, and
zooplankton. Concentrations of copper, for example, are
detrimental to some oysters above 0.1 ppm. Oysters
cultured in sea water containing 0.13-0.5 ppm of copper
deposit the metal in their bodies and become unfit as a
food substance.
Cyanide (CN)
Cyanide is a compound that is widely used in industry
primarily as sodium cyanide (NaCN) or hydrocyanic acid
(HCN). The major use of cyanides is in the electroplating
industry where cyanide baths are used to hold ions such
as zinc and cadmium in solution. Cyanides in various
compounds are also used in steel plants, chemical plants,
photographic processing, textile dying, and ore processing.
Of all the cyanides, hydrogen cyanide (HCN) is probably
the most acutely lethal compound. HCN dissociates in
water to hydrogen ions and cyanide ions in a pH dependent
reaction. The cyanide ion is less acutely lethal than HCN.
The relationship of pH to HCN shows that as the pH is
lowered to below 7 there is less than 1 percent of the cyanide
molecules in the form of the CN ion and the rest is present
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as HCN. When the pH is increased to 8, 9, and 10, the
percentage of cyanide present as CN ion is 6.7, 42, and
87 percent, respectively. The toxicity of cyanides is also
increased by increases in temperature. A rise of 10°C produced
a two- to two-to threefold increase in the rate of the
lethal action of cyanide.
In the body, the CN ion, except for a small portion exhaled,
is rapidly changed into a relatively non-toxic complex
(thiocyanate) in the liver and eliminated in the urine.
There is no evidence that the CN ion is stored in the body.
The safe ingested limit of cyanide has been estimated at
something less than 18 mg/day, part of which comes from
normal environment and industrial exposure. The average
fatal dose of HCN by ingestion by man is 50 to 60 mg. It
has been recommended that a limit of 0.%2 mg/1 cyanide not
be exceeded in public water supply sources.
The harmful effects of the cyanides on aquatic life is
affected by the pH, temperature, dissolved oxygen content,
and the concentration of minerals in the water. The
biochemical degradation of cyanide is not affected by
temperature in the range of 10°C to 35°C while the toxicity
of HCN is increased at higher temperatures.
On lower forms of life and organisms, cyanide does not seem
to be as toxic as it is toward fish. The organisms that
digest BOD were found to be inhibited at 60 mg/1 although
the effect is more one of delay in exertion of BOD than
total reduction.
Certain metals such as nickel may form complexes with cyanide
to reduce lethality, especially at higher pH values. On the
other hand, zinc and cadmium cyanide complexes may be
exceedingly toxic.
Iron jFe)
Iron is an abundant metal found in the earth's crust. The
most common iron ore is hematite from which iron is obtained
by reduction with carbon. Other forms of commercial ores
are magnetite and taconite. Pure iron is not often found
in commercial use, but it is usually alloyed with other
metals and minerals, the most common being carbon.
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Iron is the basic element in the production of steel and
steel alloys. Iron with carbon is used for casting of major
parts of machines and it can be machined, cast, formed,
and welded. Ferrous iron is used in paints, while powdered
iron can be sintered and used in powder metallurgy. Iron
compounds are also used to precipitate other metals and
undesirable minerals from industrial wastewater streams.
Iron is chemically reactive and corrodes rapidly in the
presence of moist air and at elevated temperatures. In
water and in the presence of oxygen, the resulting products
of iron corrosion may be pollutants in water. Natural
pollution occurs from the leaching of soluble iron salts
from soil and rocks and is increased by industrial
wastewater water from pickling baths and other solutions
containing iron salts.
Corrosion products of iron in water cause staining of
porcelain fixtures, and ferric iron combines with tannin
to produce a dark violet color. The presence of excessive
iron in water discourages cows from drinking and, thus
reduces milk production. High concentrations of ferric and
ferrous ions in water kill most fish introduced to the
solution within a few hours. The killing action is
attributed to coatings or iron hydroxide precipitates on the
gills. Iron-oxidizing bacteria are dependent on iron in
water for growth. These bacteria form slimes that can
affect the aesthetic values of bodies of water and cause
stoppage of flows in pipes.
Iron is an essential nutrient and micronutrient for all
forms of growth. Drinking water standards in the U.S. have
set a recommended limit of 0.3 mg/1 of iron in domestic
water supplies based not on physiological considerations,
but rather on aesthetic and taste considerations.
Nickel (Ni)
Elemental nickel is seldom found in nature in the pure
state. Nickel is obtained commercially from pentlendite
and pyrrhotite. It is a relatively plentiful element and
is widely distributed throughout the earth's crust. It
occurs in.marine organisms and is found in the oceans.
Depending on the dose, the organism involved, and the type
of compound involved, nickel may be beneficial or toxic.
Pure nickel is not soluble in water but many of its salts
are very soluble.
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The toxicity of nickel to man is believed to be very low and
systematic poisoning of human beings by nickel or nickel
salts is almost unknown. Nickel salts have caused the
inhibition of the biochemical oxidation of sewage. They
also caused a 50 percent reduction in the oxygen utilization
from synthetic sewage in concentrations of 3.6 to 27 mg/1
of various nickel salts.
Nickel is extremely toxic to citrus plants. It is found in
many soils in California, generally in insoluble form, but
excessive acidification of such soil may render it soluble,
causing severe injury to or the death of plants. Many
experiments with plants in solution cultures have shown that
nickel at 0.5 to 1.0 mg/1 is inhibitory to growth.
Nickel salts can kill fish at very low concentrations.
However, it has been found to be less toxic to some fish
than copper, zinc, and iron. Data for the fathead minnow
show death occurring in the range of 5 to 43 mg/1,
depending on the alkalinity of the water.
Nickel is present in coastal and open ocean concentrations
in the range of 0.1 to 6.0 mg/1, although the most common
values are 2 to 3 mg/1. Marine animals contain up to 400
mg/1, and marine plants contain up to 3,000 mg/1. The
lethal limit of nickel to some marine fish has been reported
as low as 0.8 ppm. Concentrations of 13.1 mg/1 have been
reported to cause a 50 percent reduction of the photosynthetic
activity in the giant kelp (Macrocystic pyrifera) in 96
hours, and a low concentration was found to kill oyster
eggs.
Phosphorus (P)
Phosphorus occurs in natural waters and in wastewaters in
the form of various types of phosphate. These forms are
commonly classified into orthophosphates, condensed
phosphates (pyro-, meta-, and polyphosphorus), and
organically bound phosphates. These may occur in the
soluble form, in particles of detritus, or in the bodies
of aquatic organisms.
The various forms of phosphates find their way into
wastewaters from a variety of industrial, residential, and
commercial sources. Small amounts of certain condensed
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phosphates are added to some water supplies in the course of
potable water treatment. Large quantities of the same
compounds may be added when the water is used for laundering
or other cleaning since these materials are major
constituents of many commercial cleaning preparations.
Phosphate coating of metals is another major source of
phosphates in certain industrial effluents.
The increasing problem of the growth of algae in streams and
lakes appears to be associated with the increasing presence
of certain dissolved nutrients, chief among which is
phosphorus. Phosphorus is an element which is essential to
the growth of organisms and it can often be the nutrient
that limits the aquatic growth that a body of water can
support. In instances where phosphorus is a growth
limiting nutrient, the discharge of sewage, agricultural
drainage, or certain industrial wastes to a receiving water
may stimulate the growth, in nuisance quantities, of
photosynthetic aquatic microorganisms and macroorganisms.
The increase in organic matter production by algae and
plants in a lake undergoing eutrophication has ramifications
throughout the aquatic ecosystem. Greater demand is placed
on the dissolved oxygen in the water as the organic matter
decomposes at the termination of the life cycles. Because
of this process, the deeper waters of the lake may become
entirely depleted of oxygen, thereby destroying fish
habitats and leading to the elimination of desirable
species. The settling of particulate matter from the
productive upper layers changes the character of the bottom
mud, also leading to the replacement of certain species by
less desirable organisms. Of great importance is the fact
that nutrients inadvertently introduced to a lake are, for
the most part, trapped there and recycled in accelerated
biological processes. Consequently, the damage done to a
lake in a relatively short time requires a many fold in-
crease in time for recovery of the lake.
When a plant population is stimulated in production and
attains a nuisance status, a large number of associated
liabilities are immediately apparent. Dense populations of
pond weeds make swimming dangerous. Boating and water
skiing and sometimes fishing may be eliminated because of
the mass of vegetation that serves as a physical impediment
to such activities. Plant populations have been associated
with stunted fish populations and with poor fishing. Plant
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nuisances emit vile stenches, impart tastes and odors to
water supplies, reduce the efficiency of industrial and
municipal water treatment, impair aesthetic beauty, reduce
or restrict resort trade, lower waterfront property values,
cause skin rashes to man during water contact, and serve
as a desired substrate and breeding ground for flies.
Phosphorus in the elemental form is particularly toxic, and
subject to bioaccumulation in much the same way as mercury.
Colloidal elemental phosphorus will poison marine fish
(causing skin tissue breakdown and discoloration). Also,
phosphorus is capable of being concentrated and will
accumulate in organs and soft tissues. Experiments have
shown that marine fish will concentrate phosphorus from
water containing as little as 1 ug/1.
Zinc (Z n)
Occurring abundantly in rocks and ores, zinc is readily
refined into a stable pure metal and is used extensively as
a metal, an alloy, and a plating material. In addition,
zinc salts are also used in paint pigments, dyes, and
insecticides. Many of these salts (for example, zinc
chloride and zinc sulfate) are highly soluble in water;
hence, it is expected that zinc might occur in many
industrial wastes. On the other hand, some zinc salts
(zinc carbonate, zinc oxide, zinc sulfide) are insoluble
in water and, consequently, it is expected that some zinc
will precipitate and be removed readily in many natural
waters.
In soft water, concentrations of zinc ranging from 0.1 to
1.0 mg/1 have been reported to be lethal to fish. Zinc is
thought to exert its toxic action by forming insoluble
compounds with the mucous that covers the gills, by damage
to the gill epithelium, or possibly by acting as an internal
poison. The sensitivity of fish to zinc varies with species,
age, and condition, as well as with the physical and chemical
characteristics of the water. Some acclimatization to the
presence of the zinc is possible. It has also been observed
that the effects of zinc poisoning may not become apparent
immediately so that fish removed from zinc-contaminated to
zinc-free water may die as long as 48 hours after the removal
The presence of copper in water may increase the toxicity of
zinc to aquatic organisms, while the presence of calcium
or hardness may decrease the relative toxicity.
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A complex relationship exists between zinc concentrations,
dissolved oxygen, pH, temperature, and calcium and magnesium
concentrations. Prediction of harmful effects has been less
than reliable and controlled studies have not been extensively
documented.
Concentrations of zinc in excess of 5 mg/1 in public water
varies widely. The major concern with zinc compounds in
marine waters is not one of accute lethal effects, but
rather one of the long term sublethal effects of the
metallic compounds and complexes. From the point of view of
accute lethal effects, invertebrate marine animals seem to
be the most sensitive organisms tested.
A variety of freshwater plants tested manifested harmful
symptoms at concentrations of 10 mg/1. Zinc sulfate has
also been found to be lethal to many plants and it could
impair agricultural uses of the water.
Pol 1utants Rejected
The pollutants bromide (Br) and surfactants were analyzed
in all samples collected. Neither pollutant was observed
in significant quantities. Therefore, bromide (Br) and
surfactants are rejected as pollutants for consideration
in this study.
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SECTION VII
TREATMENT AND CONTROL TECHNOLOGY
INTRODUCTION
Treatment and control technologies for potential pollutants
discharged from steam electric power generating plants
discharging to publicly-owned -treatment works (POTW's) are
outlined in this section. In-process controls discussed
include those techniques which are normally used by the
industry or by industries employing similar processes. Such
controls include process modifications, materials substitution,
raw materials and products recovery, water conservation and
wastewater reuse, and general good housekeeping practices.
Wastewater effluents discharged to publicly-owned treatment
facilities are sometimes treated by end-of-process physical
or chemical systems to remove pollutants which can upset
normal operation of the POTW. Such treatment methods are
numerous, but they generally fall into one of three broad
categories in accordance with their process objectives.
These include pH control, removal of dissolved materials,
and separation of phases.
Of the twenty-two plants surveyed only eight provide
end-of-pipe treatment to their waste, before discharging
it to POTW's. The extent of treatment applied varies
in accordance with the local requirements for discharge
limitations. Most of the plants use retention ponds to
equalize the flow to POTWs. These ponds also serve as
sedimentation basins for partial removal of suspended solids
by gravity settling and are sometimes equipped with
skimming devices to remove floating oil. A detailed
description of end-of-pipe treatment techniques used is
presented in Section V of this report.
A properly designed and maintained wastewater control and
treatment system is essential for an overall efficient waste
management program. In order to select and implement such a
program, it is necessary to evaluate the controls and the
treatment techniques applicable in each case. The choice of
any particular control strategy requires awareness of those
factors affecting the quantity and nature of the wastewaters
produced as well as their amenability to acceptance and
treatment by publicly-owned treatment works.
VII-1
-------
DRAFT
END-OF-PIPE TREATMENT TECHNOLOGY
Treatment Technologies Available
If a pollutant in a waste stream is not acceptable for
discharge to the publicly-owned treatment plant, end-of-pipe
treatment must be provided to remove the pollutant or reduce
it to allowable limits. Only a few existing plants
discharging into POTW provide end-of-pipe treatment. Yet,
basic technology is available to remove nearly all of the
pollutants produced by steam electric generating plants.
This technology is shown in Tables VII-1 and VII-2.
Table VII-1 lists potential dissolved matter removal
methods and Table VII-2 provides a similar list of solid
liquid separation processes. Most of the processes listed
are in use in industrial or municipal water and wastewater
treatment.
End-of-pipe treatment presents difficulties for removing
some of the chemicals used in power plants. These may
include inhibitors, biocides, and chelating agents. For
organic chemicals, activated carbon absorption is an
available technology, but the low concentration of the
organics can make the process inefficient and costly. For
some inorganics like chromates, ion exchange is similarly
available, but may not be economically feasible. For these
pollutants, in-plant controls are probably the preferred
control strategy.
TREATMENT Of MAJOR POLLUTANTS
Available technology and efficiency of their removal for
chosen pollutants are shown in Table VII-3. The following
is a brief discussion of the problems associated with
removal of pollutants from the power plant.
VII-2
-------
END-OF-PIPE TREATMENT METHODS
Method
Ne utra 1 1 zati on •
Chemi ca 1 reducti on
P r e c i pi tation
Ion exchange
Liquid/1 iguid
extracti on
object] ves
pH ad j us tment ,
us ua 1 ly to within
the range of 6-9
reducti on o f
hexa va 1 ent
chromium to
tn va 1 ent
ch romi urn
by f ormi ng slight-
ly soluble salts
remc va 1 of ions by
sorption on surface
of a sn ' i d >iia t r i x
remo va 1 of soluble
organics or chemi-
cally charged pol -
1 utants
Chpmicals or Process
equipment used requirements
requi red , usually
sulfuric acid and
lime
sulfur dioxide, pH range of
sodium bisulfite, 2-3
sodium metabisulfite,
ferrous salts
sulfide, organic depends on the
precipitants, ions to be re-
soda as h moved
synthetic cation may require pH
anion exchange adjustment
res i us
immiscible solvents may require
that may contain pH adjust me nt
chelating agents
Efficiency of
remova 1
99.7%
nickel-91 .7%
chromi um-98 - 8%
zinc-99.7%
phosphate-93. 6%
cyamde-99*.
ch romi urn- 98 %
copper-95 4
iron-100%
cadmi um-92 %
nickel -100%
zinc-75;S
phosphate-90%
sul fate-97*
al umi num-98 %
phenol -99%
chromi um-99%
nickel-99%
zinc-99%
fluoride-68*
1 ron-99*
mo Iybdenum-90%
Advantages j
ambi ent en v i ron-
ment
2-wel 1 sui ted for
au toma ti c con tro 1
3-h i gh rate of re-
actions
1 -operates at
ambient en-
v i ronmen t
2-we 11 s ui ted
to automati c
control
ambient en-
vi ronment
2-wel 1 sui ted to
automa ti c con tro 1
1 -operates a t am-
bient environment
2-wel 1 sui ted to
automati c control
3-can be used to
cons ti tuen ts
1 -can be used to
recover valu-
able cons ti tuen ts
Limitations Requi red maintenance
1-may cause periodic removal of
scaling in sludge
tanks and
condui ts
2-produces
1 arge
quanti ti es
of s 1 udge
3-may generate
toxic by-
products
1-requires periodic removal of
careful pH s Judge
con trol
2-presence of
oxidan ts
(oxygen ,
fern c ion)
i ncreases re-
qui red dose
of the reduc-
ing agent
3-Sul fur di -
oxide is
tox i c and
corros i ve
careful pH sludge
contro 1
2-may requ i re
more than a
single s tep
to remove a
mixture of
ions
3-presence of
chel ati ng
agents (i.e.,
cyan i de } i n-
creases the
solubi 1 i ty of
many metals
1-produces periodic regenera-
ef f 1 uen t
2 -res in is sub
jected to
attack by
oxidizing
agents (i.e.
ni tn c acid)
3-subjected to
c logg J ng and
fou 1 i ng
4-costly to
opera te
1-effluent re- periodic regenera-
quired addi- ti on of solvent
tional
treatment
2-subjected to
chemi cal i n-
terference
3-solvent sys-
tem may
deteriorate
wi th repeate
use
Demonstration status
practiced extensively
by industry
practiced extensively
by i n d u s t ry
by i ndu s t ry
used primarily in water
production of boiler feed-
water
process is not highly
developed for industrial u:
(except phenol extraction)
-------
END-OF-PIPE TREATMENT METHODS
Method
Disinfection
Adsorption
Chemical oxidation
I
CO
cc
Distillation
Reverse osmosis
Electrodialysis
objecti ves
destruction of
microorganisms
removal of sorbable
co ntami nants
destruction of cya-
n 1 des
separati on of dis-
solved matter by
e vaporati on of the
water
separation of d1s-
sol ved matte r by
f i 1 trati on through
a semi permeabl e
membrane
removal of
dissolved
polar compounds
Chpmicals or Process
equipment used requirements
chlorine, hypo- may require pH
chlorite salts, adjustment
pheno 1 ,pheno 1
derivatives, ozone,
salts of heavy
meta Is, chlorine
dioxide
activated carbon, may require pH
synthetic sorbents adjustment
chlorine, hypochlo- DH=9 5-10
rite salts, ozone (first step)
pH=8 (second
step)
1-multistage flash may require pH
di sti 1 lati on adjustment
2-mul tiple-effect
1 ong- tube verti-
ca 1 e vaporati on
3-submerged tube
evaporation
4- vapor compres-
sion
1 -tubular membrane
2-hollow-fi Her
modu 1 es
3-Spi ral-wound flat
sheet membrane
solute is exchanged
between two liquids
through a selective
semlpermeable mem-
brane in response to
differences in chemi-
cal potential between
two liquids
Efficiency of Advantages
remo va 1
1 -operates at
ambient en-
vi ronmen t
2-wel V sui ted to
automa ti c contro 1
depend on the l-high removal ef -
nature of pol- ficiency for traci
lutants and com- concentration
position of 2- low, energy re-
waste qu i remen t
3-oper ates a t am-
bient en vi ronment
99.6% 1 -operate at am-
bient tempera ture
2-wel 1 sui ted to
automa ti c
con trol
100% 1 -produces high
qua 1 i ty water
2-can be used to
recover va 1 u-
abl e cons t i t-
TDS-93* 1 -produces high
qual i ty water
2-can be used to
recover val uabl e
cons ti tuents
3-operates a t am-
bient tempera-
ture
TDS-62-96% 1-can be used to
recover and re-
use valuable
chemicals
2-produces high
qual i ty water
Limitations
1-may cause
taste and
color pro-
blems
2-di s i n fectan t
are toxic
compounds
1 -waste re-
e qui red pre-
treatment
2-bed requi red
regenerati on
3- 1 os ses of
sorben t
during re-
generati on
1 - requ i re ca re-
ful pH con-
trol
2-may produce
poi sonous
gas
3-second re-
action is
slow
4-s ubjected to
chemical
i nterfe rence
1 -hi gh energy
requi rement
2-may requi re
pretrea tment
of waste
ing of
boi 1 ers and
heat ex-
changers
4-may requi re
post treat-
ment of
wate r
1 - 1 i mi ted range
of operating
temperatures
and concen-
trations
2-membrane i s
susceptible
to fouling by
suspended
solids or
attack by
many chemi -
cals
1 -membrane i s
subjected to
fou ling by
suspended
solids
2-membrane and
electrode are
subjected to
corros i on by
chemicals
Requi red maintenance
periodic loading
of ciiemi cal s
periodic regenera-
tion of sorbent
periodic removal of
s 1 udge and 1 oadi ng
of chemi cals
periodic cleaning to
remove scale
periodic replacement of
membrane
periodic replacement of
membranes and electrodes
Demonstration status
disinfection by chlorine
is practiced extensively
by industry
practiced extensively
by industry
practiced extensively
by industry
practiced only to a moder<
extent by industry, primai
the submerged tube type ui
very 1 i ni ted use in
industrial wastewater
treatmen t
not practiced by
industry
-------
END-OF-PIPE TREATMENT METHODS
Method
obj ectives
Chemicals or
equ i pment used
Process
requirements
Efficiency of
remova1
Advan tages
Limitations'
Required maintenance
Demonstration status
Freezing
separa ti on of so-
lute from 1 i 0, u ) d
by crystal 11zing
the solven t
1-direct refriger-
ation
2-indirect refrig-
eration
>99
1-produces high
quality water
2-low operating
temperature
inhibits
corrosion
1-high energy
requiremen t
2 -refrigeran t
may be con-
tain! nated in
the direct
refrigeration
method
periodic cleaning and re-
placement of filters and
screens
unproven method in
waste treatment
application
I
OJ
O
-------
SOLID/LIQUID SEPARATION SYSTEMS
Unit operation
Process objectives
Methods or
units used
Retention
time
Chemicals Efficiency
used of removal
Advantages
Skimming
Clarification
Flotation
Mlcrostraining
Filtration
removal of floating
solids or liquid
wastes from the water
removal of suspended
solids by settling
separation of sus-
pended solids by
flotation followed by
sk immi ng
removal of suspended
solids by passing the
wastewater through a
mi croscreen
removal of suspended
solids by filtration
through a bed of sand
and gravel
1-settling ponds
2-clarifiers
1-15 min
45 min
1-froth flotation
2-dispersed air
flotation
3-dissolved air
flotation
4-gravity flotation
5-vacuum flotation
20-30
min
N/A
l-multimed1a bed N/A
2-mixed media bed
70-90%
to
coagulants , 15 mg/1
coagulant aids,
pH adjustment
aluminum and 90-991
ferric salts,
activated si-
lica organic
polymers
70-80*
(23/0
50-60*
(3/0
50-99*
1-simple to operate
2-reduces down stream
treatment
3-h1gh efficiency of
removal
1-high efficiency of
removal in short
time and space
l-eff1c1ent process
1-no chemicals require-
ment
2-low cost of opera-
tion and maintenance
3-high efficiency of
removal of large
particles
1-low initial and
operating costs
2-small land re-
qu1rement
3-no chemicals re-
quirement
4-partial removal of
dissolved matter
Screening
Thickening
Press ure
filtration
Heat drying
Ultrafi1tration
removal of large solid
matter by passing
through screens
concentration of
sludge by removing
water
1-coarse screens
2-bar screens
3-communicating
devi ces
1-gravity thick-
ening
2-air flotation
thickening
separation of solid from
liquid by passing
through a semipermeable
membrane under pressure
reduce the water content 1-flash drying
of sludge 2-spray drying
3-rotary kiln
d ry 1 n g
4-multiple hearth
d ry 1 n g
separation of macro-
molecules of sus-
pended matter from the
waste by filtration
through a semipermeable
membrane under pressure
N/A
N/A
1-3 hrs
N/A
N/A
50-99*
depends on
the nature
of sludge
to 50-75%
moisture
content
to 8%
mo1sture
content
Total solid
removal of
95% and
above
1-protect down stream
treatment equipment
2-1nexpens1ve devices
1-facilUates further
sludge processing
at minimum cost
2-flotation thickeners
are more efficient
than gravity thick-
eners
l-h1gh separation
efficiency for
difficult to re-
move solids
2-f1lter cake has a
low water content
3-suspended solids
content of fi1 -
trate 1s low
4-min1mum maintenance
1-produces dis-
posable product
1-low capital instal-
lation and operating
costs
2-unsens1tlv1ty to
the chemical nature
of waste
3-no waste pre-
treatment 1s re-
quired
Sandbed drying
Vacuum
filtration
removal of moisture
from sludge by evapor-
ation and drainage
through sand.
solid liquid
separation by vacuum
1-covered beds
2-uncovered beds
f11tration
1-2 day
as filter
15-20*
produces
30* solid
in filter
cake
1-low costs of
cons trueti on,
operation and
ma1ntenance
1-highly efficient
process
Centrifugatlon
liquid/solid separ-
ation by centrifugal
force
1-disc centrifuge N/A
2-basket centrifuge
3-conveyor type
centri fuge
moisture is
reduced to
65-70*
1-small space
requi rement
2-s1mpl1ci ty in
operati on
Emulsion
breaklng
separation between
emulsified oil and
water
2-8 hour
VII-4A
aluminum
salts, iron
salts , pH
adj us tment
(3-4)
>99t
1-highly efficient
process
-------
SOLID/LIQUID SEPARATION SYSTEMS
Unit
opera ti on
Skimming
Limitation
1-Hmited to
con ta1 ni ng
matter
wastewater
floating
Ene rgy
requi remen t
smal 1
Maintenance
periodic
cation
lubri-
Demonstratlon
status
practi ced
industry
extens i vely
by
Clarification
Flotation
1-Mgh operating cost
nomina1
1-efficiency depends on nominal
the nature of the par-
ticles surface
periodic loading practiced extensively by
of chemicals and industry
removal of sludge
routine maintenance practiced extensively by
of pumps and motors Industry
M1crostra1ning
1-may result in high
head loss
2-low efficiency of
removal of small
particles
smal 1
routing cleaning
of screens
practiced only to a moderate
extent, primarily in municipal
wastewater treatment plants
Filtration
Screening
Thickening
1-wastewater with high small
suspended solids con-
tent requi re pre-
treatment
2-high losses of head
3-produces wastewater
4-operation is com-
11cated and re-
qulres training
1-minor effect on small
overall treatment
2-may result 1n high
ha ad loss
1-sensitive to flow small
rate of both
effluent and sludge
removal
routine main-
tenance of pumps
practiced extensively primarily
in water treatment plant
periodic cleaning
periodic cleaning
lubrication
practiced extensively
by industry
practiced extensively
by Industry
Pressure 1-short life of filter
filtration cloth
2-requ1res operating
personnel
small
periodic cleaning
and replacement
of filter
not practiced by
Industry
Heat drying
1-costly process
high
periodic cleaning
rotary kilns are used
by Industry to small
extent
Ultrafi1tration
l-]im1ted range of
operating tempera-
ture
2-membrane is sus-
ceptible to attack
by many chemicals
3-limited range of
app11 cations
4-membrane can be
fouled by suspended
solids
nomi nal
routine maintenance used by industry
of pumps primarily to treat
ofly waste
Sandbed drying
1-requires a large
area of land
small
periodic removal
of sludge
practiced extensively
by Industry
\
Vacuum
filtration
Centrlfugati on
1-hiop operating nominal
cost
2-flltrate may re-
quire further
treatmen t
l-h1gh operating nominal
cost
2-may produce noise
periodic cleaning
and replacement
of filter media
periodic lubrica-
tion and cleaning
practiced extensively
by Industry
equipment for in-
dustrial wastewater
treatment is under
development
Emulsion
breaking
1-requires segre-
gation of o1ly
waste from non
ol ly waste
small
routine maintenance practiced extensively
of pumps and motors by industry
and periodic re-
moval of sludge
V11-46
-------
DRAFT
Table VII-3. TREATMENT OF MAJOR POLLUTANTS
Pollutant
Common
pH
Total suspended solids
Specific
0i1 and Grease
Hexavalent chromium
Chromium (total)
Iron
Copper
Zinc
Chlorine
Treatment method
1 - Neutralization
1 - Clarification
2 - Flotation
3 - Filtration
1 - Skimming
2 - Gravity flotation
3 - Dissolved air flotation
1 - Chemical reduction
1 - Precipitation
2 - Ion exchange
1 - Precipitation
1 - Precipitation
2 - Ion exchange
1 - Precipitation
2 - Ion exchange
1 - Dissipation
2 - Aeration
3 - Chemical reduction
Residual concentration
achievable (mg/1) (17)
to pH of 5.5 to 9
5-30
5-15
2-10
10-30
20
15
0-1
0.006
0.01
0.3
0.1
0.03
0.5-2.5
20
Below detection limits
Below detection limits
Below detection limits
VII-5
-------
DRAFT
IpjtaJ_ Dissolved Sol ids. Removal of total dissolved
solids (IDS) from wastewaters is one of the more difficult
and more expensive waste treatment procedures. Where IDS
result from heavy metal or hardness ions, reduction can be
achieved by chemical precipitation methods; however, where
dissolved solids are present as sodium, calcium, or potassium
compounds, then IDS reduction requires more specialized
treatment, such as reverse osmosis, electrodialysis,
distillation, and ion exchange.
Tc^tal Suspended Solids^ Suspended solids removal can
be achieved by sedimentation and filtration operations.
Sedimentation lagoons are commonly used at steam electric
power plants. Some plants employed configured tanks
Tanks can be used where space limitations are important.
Tanks constructed for solids removal usually have built-in
facilities for continuous or intermittent sludge removal.
Designs based on maximum flow anticipated can provide the
best performance. Equalization can be provided to regulate
flow. The retention time required is related to the
particle characteristics.
Oj_l and Grease. Certain preventative measures can be
applied to prevent spillage of oil and the entrance of oil
into the plant drainage system. Flotation is efficient in
removing emulsified oil and requires minimum space. It
can be used without chemical addition, but demulsifiers
and coagulants can improve performance in some cases.
Whenever possible, primary separation facilities should be
employed to remove free oil and solids before the water
enters the flotation unit. Multistage units are more
effective than single-stage units. Partial recycle units
are more effective than ful1-pressure units. Oil removal
facilities including single-cell flotation can achieve
effluent oil and grease levels from 10-20 mg/1 , while
multistage units can achieve 2-10 mg/1.
Chromium. The most common method of chromium removal
is chemical reduction of hexavalent chromium to the
trivalent ion and subsequent chemical precipitation. The
standard reduction technique is to lower the waste stream
pH to 3 or below by addition of sulfuric acid, and to add
sulfur dioxide, sodium bisulfite (or metabisulfite or
hydrosulfite), or ferrous sulfate as a reducing agent.
Trivalent chromium is then removed by precipitation with
lime at pH 8.5-9.5.
The residual of hexavalent chromium after the reduction step
depends on the pH, retention time, and the concentration and
type of reducing agent.
VII-6
-------
DRAFT
A process for chromate removal from cooling water has been
recently developed. This is an electrochemical process
whereby an electrical current is applied to a consumable
iron electrode. The resulting ferrous ions react with the
wastewater chromate in accordance with the following equation
3 Fe2± + Cr01= + 4 H20 = 3 Fe^+. + Cr3± + 80H^ (1)
Because of the alkaline pH both the iron and chromium
precipitate as metal hydroxides and are subsequently
removed in a clarifier. The produced ferric ion further
enhances the coagulation and settling of suspended solids.
Chromate residuals from this process have been reported to
be less than 0.05 ppm. Costs of treatment are claimed to
be fairly low and the operation is automatically controlled.
The process is also applicable for removal of other metals
ions such as zinc, copper, nickel, tin, iron, etc. (16).
Copper. Effluent concentrations of 0.5 mg/1 can be
consistently achieved by precipitation with lime employing
proper pH control and proper settler design and operation.
The minimum solubility of the metal hydroxide is in the
range of pH 8.5-9.5. In a power plant, copper can appear in
the wastewater effluent as a result of corrosion of copper-
containing components of the necessary plant hydraulic
systems. Normally, every practicable effort is made, as a
part of standard design and operating practice to reduce
corrosion of plant components. Copper is not usually used in
construction of once-through boilers and consequently, is
rarely found in corresponding spent cleaning solutions (12).
Excessively stringent effluent limitations on copper may
necessitate complete redesign and alteration of condenser
cooling and other systems. A significant problem in
achieving a low residual concentration of copper can result
if complexing agents are present, especially cyanide and
ammonia .
Iron. In general, acidic and/or anaerobic conditions
are necessary for appreciable concentrations of soluble
iron to exist. "Complete" iron removal with lime addition,
aeration, and settling followed by sand filtration has been
reported. Existing technology is capable of soluble iron
removals to levels well below 0.3 mg/1. Failure to achieve
these levels would be the result of improper pH control.
olubility of ferric hydroxide is between 7 and
The minimum sol
8 (12). In
present as
8 (12). In some cases, apparently soluble iron may actually be
finely divided solids due to inefficient settling
_ _ • i i
if | COCMI* u o i i 11 c i v vjiv i vi v. ^j *j \j * i vi *j v« M v> i> v i 11 v>. i i i x* i ^» 11 w « »•» ** ** • « • • j
of ferric hydroxide. Polishing treatment such as rapid sand
filters will remove these solids. In a power plant, iron,
VII-7
-------
DRAFT
as with copper, can appear in the wastewater effluent as
a result of corrosion to iron-containing components of the
necessary plant hydraulic systems. Normally, every
practicable effort is made, as a part of standard design
and operating procedure, to reduce corrosion of plant
components. Excessively stringent effluent limitations on
iron, as with copper, may necessitate complete design and
alteration of condenser cooling and other systems.
Zinc. Lime addition for pH adjustment can result in
precipitation of zinc hydroxide. Operational data indicate
that levels below 1 mg/1 zinc are readily obtainable with
lime precipitation. The use of zinc can be minimized since
other treatment chemicals are available to reduce corrosion
in closed cooling water cycle. Zinc removals have been
reported for a range of industrial systems and, generally,
treatment is not for zinc alone.
END-OF-PIPE TECHNOLOGY FOR^ MAJOR WASTE STREAMS
The regulations describe the various wastewater streams as
low volume waste sources, ash transport water, metal clean-
ing wastes, boiler blowdown, and cooling system wastes. It
is also possible to classify wastewater streams by their
temporal distribution into continuous, periodic, and
occasional. Continuous wastewater streams will have to be
treated on a continuous basis. The main treatment criteria
is therefore the rate of flow. Periodic wastewater streams
will generally be treated on a batch basis and discharged
at a controlled rate. The treatment criteria are there-
fore the volume of each batch, the frequency of occurrence,
and the rate of discharge from treatment. The occasional
waste streams are generally produced by outside conditions
not related to the production of electrical energy such as
precipitation.
Some waste streams such as cooling water are directly
related to the production of electrical energy and will not
be discharged if the plant is not producing power. Others
are related to the cumulative amount of energy produced by
the plant, but may be discharged at the time the plant is
not in operation. Metal cleaning wastes are an example of
this type of waste.
VII-8
-------
DRAFT
Continuous Haste Streams. Continuous wastewater
streams consist primarily of cooling system wastes,
either of the once-through or the recirculating system
blowdown type. None of the plants contacted in this study
were found to discharge once-through cooling water to
publicly-owned treatment facilities. Where such discharge
occurs, consideration should be given to removing this
discharge from the sanitary sewer system, since none of
the possible pollutants in the cooling water will be
removed by standard biological treatment and the large
hydraulic loading will decrease the effectiveness of the
POTW treatment process.
Residual chlorine contained in once-through cooling water
discharges can be removed by so-called "dechlorination"
processes. Methods of dechlorination .include addition of
reducing chemicals, passage through fixed beds of activated
carbon and aeration. Reducing chemicals include sulfur
dioxide (S02J, sodium bisulfite (NaHSO_3), and sodium sulfite
(Na2_S03_). Of these agents, sodium bisulfite is most
commonly used (19). Granular activated carbon as adsorb
chlorine compounds and is oxidized by it to carbon dioxide.
Oxidizing chlorine compounds such as chlorine (C12J,
hypochlorous acid (HOC1), chlorine dioxide (C102J and
nitrogen trichloride (NC13J are sufficiently volative to be
removed by aeration (19). Other active chlorine species are
not as volatile and may not be removed. Data available to
date do not indicate that heat discharged in this waste is
a problem to a POTW.
Closed cycle or recirculating cooling water system blowdown
is discharged into POTWs by a number of plants. The discharge
may be continuous or intermittent. Significant parameters
of pollutants that may be found in cooling water blowdown
may include chlorine, hypochlorous acid, sodium hypochlorite,
phosphates, chromates, zinc compounds, organic biocides,
dispersing agents, and depending on the constituents in the
makeup water supply, various inorganic salts resulting from
the concentration of those constituents and the necessity of
maintaining the pH within certain limits. Pretreatment may
be necessary if certain types of inhibitors and biocides are
used as internal treatment in the cooling water system.
These are likely to inhibit biological activity at the
publicly-owned treatment facilities and will therefore have an
adverse effect on the treatment operation. The extent of
this effect will depend on the relative volumes of boiler
blowdown and domestic wastewater. Organic compounds used as
inhibitors, biocides, or dispersing agents are not likely to
be degraded by secondary biological treatment and will
therefore pass through the publicly-owned treatment facilities
and be discharged to the receiving waters. Toxicity studies
are being conducted with individual proprietary compounds in
order to establish permissible levels of discharge.
VII-9
-------
DRAFT
End-of-pipe technology is available to remove most inorganic
pollutants. Many inorganic pollutants are insoluble at
alkaline pH, and can be removed by adding lime or another
form of alkali. The degree of removal is a function of the
solubility of the pollutant at high pH. Some specific
pollutants such as chromium can be removed by ion exchange,
but the ultimate disposal of the spent regenerants presents
problems.
Periodic Wastes. Periodic wastes include waste resulting
from boiler and service water treatment, boiler blowdown
(can be continous), ion exchange water treatment, water
treatment evaporative blowdown, boiler and air heater
cleaning, other equipment cleaning, laboratory and sampling
streams, floor drainage, cooling tower basin cleaning,
blowdown from recirculating wet-scrubber air pollution
control systems, and other relatively low volume streams.
These include all the wastes that are classified as "ash
transport" and "metal cleaning" wastes. For plants
discharging wastes to publicly-owned treatment facilities,
boiler blowdown is generally not a significant source of
pollution. Water treatment wastes may or may not be
significant depending on the source of the water and method
of treatment. Since most plants discharging wastes to
publicly-owned treatment facilities also obtain their water
from the municipal water supply system, the wastes will
consists of normal constituents of the water supply, plus
any chemicals used in the treatment process. If the
treatment process is ion exchange, the wastes will contain
inorganic acids and alkalis. Combination of watest from
anion and cation exchanges will generally result in combined
waste stream that is acceptable to the treatment plant. If
the pH of the combined waste stream is outside the range of
6.0 to 9.0 normally acceptable to biologically based
treatment process, neutralization may be required.
Evporation blowdown is usually high in dissolved solids,
but otherwise acceptable for discharge to the publicly-owned
treatment facilities. The dissolved solids consists primarily
of concentrated constituents of the public water supply and
do not have any adverse effect on the treatment plant or the
receiving water.
Floor drains may be a significant source of pollution, with
oil and grease as the most significant parameter. The
regulations for direct discharge limit oil and grease for
all low volume wastes taken collectively to 100 mg/1 on any
one day, and 30 mg/1 average for 30 consecutive days, but
local authorities may impose more severe limits. Most
municipal pretreatment ordinances also limit oil and grease
so that pretreatment may be required for removal of this
pollutant.
VII-10
-------
DRAFT
End-of-pipe technology is available and is used by some
plants. The technology consists of gravity separators,
either unassisted or assisted by flocculants and/or dissolved
air flotation, followed if necessary by filtration. The
technology is able to meet the desired standards at a
minimal cost. However, to meet desired standards efficiently
only those waste streams containing excessive oil and grease
should be passed through the treatment unit.
Metal Cleaning Hastes. The most significant of the
periodic wastes in terms of their potential impact on the
publicly-owned treatment facilities are metal cleaning wastes.
Metal cleaning wastes are produced intermittently while
units are shut down. The efficiency of electric power
production depends largely on the efficiency of heat transfer
between the combustion products and the boiler water. All
metallic heat transfer surfaces have a tendency to either
corrode or collect deposits. Both corrosion products and
deposits reduce the efficiency of heat transfer and must
therefore be removed periodically.
There are two main types of cleaning operations: waterside
and fireside. Waterside cleaning consists of cleaning the
inside of tubes, and other boiler water passages. Due to
the inaccessibility of these surfaces, the only practical
and generally accepted method of cleaning is by chemical
means. The cleaning typically proceeds in three stages: a
bromate soak, an acid cleaning (usually inhibited hydrochloric
acid), and finally a passivation stage. The total operation
takes about two days and produces about five boiler volumes
of wastes, with each stage consisting of a fill, drain, fill
and rinse operation lasting about 1-1/2 1/2 to 2 hours. For
multiunit plants, only one boiler is cleaned at any one
time, so that the majority of the plant is operating during
the cleaning cycle.
Fireside cleaning is more mechanical, consisting of high
pressure nozzles directed against the surfaces to be cleaned.
The cleaning solution often contains alkalis to dissolve
oil, and grease and detergents to keep the removed material
in colloidal suspension. Fireside cleaning is done on both
the boiler and the air preheater.
Pollutants contained in the cleaning solutions consist of
both the chemicals used in the cleaning solution and the
material removed from the heat transfer surfaces. Tables
VII-4 and VII-5 give ranges of composition for chemical
cleaning and fireside cleaning wastes, respectively. These
pollutants are generally not removed by biological secondary
treatment and may have an adverse effect on the treatment
process, depending on the ratio of metal cleaning wastes to
total flow at the publicly-owned treatment plant.
VII-11
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DRAFT
Table VII-4.TYPICAL COMPOSITION 0£
BOILER CHEMICAL CLEANING WASTES
Component Amount. Ib.
Hydrochloric Acid 46,500
Iron 3,800
Copper 500
Sodium Borate 930
Ammonium Carbonate 1,675
Ammonium Hydroxide 14,600
Chromate Inhibitors 1,600
Thiourea 7,750
Ammonium Bifluoride 3,775
Sodium Carbonate 7,750
plus small amounts of silica, phosphates, nickel,
zinc, aluminum, titanium, manganese and magnesium
Size of unit 500 MW
Volume of wastes 95,000 gal
Table VII-5.TYPICAL COMPOSITION 0£
BOILER FIRESIDE HASH WASTES
Component Concentration, m
Suspended Solids 1,000 - 3,000
Iron 500 - 1,000
Copper 10 - 20
Nickel 50 - 300
Zinc 15 - 25
Oil and Grease 150 - 300
Volume, gal/KW IGC 200 - 1,000
(t)nce/year for each boiler)
VII-12
-------
DRAFT
Options for process modifications for metal cleaning wastes
are small. End-of-pipe technology is available for the
removal of most of the pollutants resulting from metal
cleaning operations.
Basic technology for removing pollutants from the waste
stream consists of retention, storage and combination of
waste streams, raising the pH to precipitate metallic salts,
and pH readjustment for discharge to public sewers.
With the increased use of organic materials for cleaning
solutions, the use of incineration in power plant boilers
has become a practical alternative for the disposal of
chemical cleaning waste. One limitation on the use of
incineration is the need for a reserve boiler to incinerate
the wastes. However, in the vast majority of cases, power
plants consist of at least two units, so that this limitation
would only occur in a few instances. Further, power plants
with only one boiler can store cleaning wastes in holding
tanks and incinerate them when the cleaning operation is
over.
Since metal cleaning wastes are only rarely produced,
(some plants clean their boiler only once every five years)
many plants prefer to have them hauled off and treated by
private contractors. Most of the expertise for treating
cleaning wastes has been developed by the cleaning contractors
who are generally being asked to include waste treatment
and disposal as part of the cleaning contract.
Ash Transport Hater. Hydraulic systems for handling
bottom ash are used primarily by coal-fired plants. The
preliminary listing of plants discharging to publicly-owned
treatment plants contain coal-fired plants. Hydraulic
systems are used for fly ash removal, usually in conjunction
with scrubbers for sulfur dioxide removal. Where scrubbers
are part of the air pollution control system, provision has
to be made for handling of the sludges resulting from the
operation. This sludge is not suitable for disposal to the
public sewer system.
Air Pollution Control Wastes. There is normally no liquid
effluent from sulfur dioxide scrubbers. The water within
the system is usually recycled as much as possible by
dewatering the sludge to a filter cake. Some water leaves
the system as steam with the gaseous emissions and some
water becomes entrained in the sludge cake, but the objective
of good operation is to minimize the amount of water in the
sludge cake. The water retained in the sludge cake is
sufficient to meet the requirements for system blowdown.
VII-13
-------
DRAFT
Occassional Wastes. Occassional wastes are those that
are caused by contamination of stormwater runoff by materials
stored on the plant site. The principal type of contaminated
stormwater is coal pile runoff, and this is restricted to
coal fired plants. A significant number of urban plants
have been converted from coal to oil fired, but still retain
the coal capability and may keep a coal reserve stored on
the site. The coal reserve may become a significant source
of pollution due to the interaction of water and air with
some of the impurities in the coal, notably iron and sulfur.
No plants discharging coal pile runoff to publicly-owned
treatment facilities were uncovered during the industry
survey.
A type of process modification would be to cover the coal
pile with plastic sheeting the way a baseball infield is
covered in the rain. This would eliminate the formation of
waste stream. Alternately, the waste stream, once produced,
can be neutralized with lime as an end-of-pipe treatment,
and any suspended solids allowed to settle. This practice
is common in related industries.
WATER MANAGEMENT
The varied uses that are made of water in a power plant and
the wide range of water quality required for those uses
present this industry with an unusual opportunity for water
management and wastewater reuse. Since power plants dispose
a great portion of their water by evaporation, it is feasible
that such plants can be operated with zero water discharge.
Indeed, many plants developed water management programs that
make use of all the wastewater streams produced by recycling
them into unit processes which tolerate lower water quality
(e.g. ash handling). However, to develop and implement a
water management program of no discharge, it is necessary to
evaluate the water requirement of each segment of the
process as well as the specific factors which affect
individual plant water needs. Such factors include the
nature of the raw water source, the location of the plant
and its climatic environment, water availability and water
cost, and the local requirement for effluent limitations.
VII-14
-------
DRAFT
The chemical composition of the raw water source affects the
magnitude of the discharge from almost every segment of the
process. To deionize water with high dissolved solids
content to produce boiler feedwater, the ion exchange system
must be regenerated more often. Further, highly dissolved
solids contents would also lower the concentration cycle of
closed-loop recirculations cooling system, and therefore
would increase the blowdown from these systems. In areas of
excessive rainfall closed-loop recirculating systems would
have to be bled more often to prevent the systems from
overflowing and may indeed be difficult to operate. In
areas where the rate of evaporation is greater than the rate
of precipitation, such systems would require makeup water to
maintain the flow. Water availability and cost would have
an impact on the plant incentive to conserve water. The
extent of wastewater treatment provided by the plant would
depend on how stringent the local requirement for effluent
limitations are.
IN-PLANT CONTROL TECHNIQUES
Control of wastewater effluents produced by the industry can
be best achieved by incorporating in-process changes capable
of reducing the volume of wastewater discharged, or reducing
the amount of pollutants in the discharge.
Such changes can be classified under one of the following
categories:
Process modifications;
Materials substitution;
Water conservation and wastewater reuse;
Raw materials and product recovery; and
Good housekeeping practices.
Application of such techniques can result in multiple
benefits, including savings in construction and operation
costs of on-site wastewater treatment plants and in sewer
surcharge and other charges associated with the use of
publicly-owned treatment facilities.
In power generating plants there are theoretical opportunities
for a number of such control measures. Practically, the
opportunities are limited by the cost of any major process
change under "retrofit" conditions, that is, conditions
which require substantial mechanical and structural changes
to an existing plant.
Process Modifications
A great number of process modifications are available to
reduce the quantities of wastewater from a power generating
plant, or to eliminate it altogether. In order to present
VII-15
-------
DRAFT
these potential modifications in an orderly manner, this
section has been further divided into subsections, each
dealing with an individual wastewater stream.
Once Through Cool ing Hater. Switching from a once-
through to a closed or open recirculating cooling system
would greatly reduce the amount of wastewater discharged.
This can be shown by balancing the quantity of heat rejected
by each of the systems. For a once-through cooling system
this quantity is equal to the product of the water flow
times the condenser temperature rise. -For a recirculating
system it can be assumed that all the heat is rejected by
evaporation. Neglecting drift and windage losses the
following equation can be written:
i = AT (2)
F qT^lT
where B/F is the ratio of the blowdown from a recirculating
system to the discharge from once-through cooling system,
AT is the condenser temperature rise, q is the amount of
heat required to evaporate a unit weight of water, and C is
the concentration cycle. The concentration cycle is defined
as the ratio of the concentration of a limiting parameter in
the makeup water to that in blowdown. For a typical condenser
temperature rise of 10°C and for q equal to 555 kcal/liter
of water, even at a concentration cycle of 2, approximately
98 percent reduction in the volume of wastewater produced
would be achieved. This reduction in cooling water
consumption can also be classified under water conservation
and wastewater reuse category.
Switching from once-through to a recircul ating cooling
syste, however, is costly and not always feasible. Power
plants, contacted in this study that utilize once-through
systems discharge the effluent directly to surface water.
Such discharges are subjected to EPA regulations which
limit the temperature and the chlorine concentration of
waste effluents to be discharged to surface water.
Excess total residual chlorine concentration in effluents
from once-through cooling system can be minimized by monitoring
and controlling free available chlorine concentrations in
the discharge stream. A further technique to reduce total
residual chlorine discharged is to chlorinate during periods
of low condenser flow. Alternatively, the chlorine input to
once-through cooling water can be reduced to a level below
the concentration required for complete fouling control.
Any biological growth which may result would be removed by
mechanical means (12). This approach however, is limited by
the configuration of the process piping and structures
involved at any plant.
VII-16
-------
DRAFT
Closed Condenser Cool ing System Slowdowns. Although
the volume of recirculating cooling system blowdown is
considerably smaller than the amount of wastewater discharged
from a once-through system, it is also significantly more
polluted. The effluent contains a higher dissolved solids
concentration due to the evaporation of a large portion of the
cooling water. In addition, chemicals added to inhibit
scale formation, corrosion, and fouling would also be
present in the blowdown water.
Blowdown from a recirculating cooling system can be
disposed of by evaporation. In warm, dry climates, and
where land costs are relatively low, such as in the southwest,
blowdown streams can be collected in ponds and allowed to
evaporate. Such ponds are usually lined with impervious
material such as clay or plastic to prevent water infiltration
and subsequent pollution of the groundwater aquifer (12).
The residual chlorine concentration in blowdown streams
discharged to POTW's can be controlled. This can be achieved
by one of the following methods:
• Regulation through feedback instrumentation;
9 Splitting the condenser effluent into two streams
and chlorinating one at a time;
• Reducing the length of the chlorination period;
• Substituting ozonation for chlorination.
A number of advantages of ozonation over chlorination for
the disinfecting of water have been recently cited. These
advantages can be summarized as follows: 1) ozone neither
increases the inorganic salt content nor produces pollutants
after reactions; 2) ozone does not impart taste, color, or
smell to the treated water; 3) ozone is a much more powerful
disinfectant than chlorine; 4) ozone does not have any known
harmful effect on aquatic life; and 5) ozone does not have
undesirable residual effects as it readily breaks down into
oxygen.
Chlorination, on the other hand, is now being questioned by
health authorities who must meet increasingly stringent
bacteriological and waste discharge requirements. An
increased chlorine dosage which may provide satisfactory
disinfection requirements may also be responsible for
VII-17
-------
DRAFT
release of an excessive amount of polluting material to
the aquatic environment. Current reports show that even
trace amounts of chlorine are harmful to aquatic life (12).
Water Treatment Wastes. Substitution of reverse
osmosis or electrodialysis for ion exchange to produce
boiler feed water will greatly reduce the discharge from
this section of the process. However, the technical feasibility
of the reverse osmosis process is limited by the chemical
characteristics of the raw water source and by economics,
and for some plants polishing the product water by ion
exchange will still be necessary, depending on the boiler
operating pressure.
A substantial reduction in wastewater can also be achieved
by preparing boiler feed water in a combined system consisting
of the hot lime and the ion exchange processes (12). The
raw water would be initially softened by the hot lime process
to remove a portion of the dissolved matter and then deionized
in an ion exchange system. Because of the reduced dissolved
matter load on the ion exchanges the system would have to be
regenerated less frequently, and consequently, would generate
less wastewater. Combined systems consisting of hot lime and
zeolite deionization processes are used by plants 9369, 7116,
and 6387.
Ash Handling Wastes. Ash handling is the conveyance of the
accumulated bottom and fly ash combustion solid waste product
to a disposal system. This is accomplished by dry or wet
processes. In the dry process the ash is transported to the
disposal area by pressurized air, vacuum, or mechanical means.
Dry ash handling systems do not generate wastewater and may
allow a credit for the sale of the ash for its metal content.
Bottom ash from oil fired furnace, for example, can be sold
for its vanadium content.
The wet process can be either open or closed-loop systems.
In the closed-loop system the ash is slurried in water and
conveyed to a clarifier where settling occurs. The clarified
overflow from the settling pond is returned to the boiler.
The closed-loop ash handling system does not generate
wastewater except in areas of excessive rainfall where the
system must be periodically bled. In such cases the blowdown
must be treated in a separate system to remove metal ion by
precipitation and suspended solids by clarification. In
areas where the rate of evaporation is higher than the rate
of precipitation, evaporation losses from closed-loop ash
handling systems can be supplemented with wastewater from
other unit processes such as cooling tower blowdown.
Open-loop ash handling systems are a source for wastewater
VlI-18
-------
DRAFT
since the transporting water is used but once to convey the
ash to the settling ponds. This wastewater source can be
eliminated by switching to dry or closed-loop type systems.
Open-loop ash handling systems should be avoided when
possible as the effluent from the ash pond may require
additional treatment before it can be discharged.
Coal Pile Runoff. The extent of contamination of coal
pile runoff can be reduced by properly constructing the coal
storage area. Coal piles can be sprayed with tar or covered
with plastic sheeting to seal the surface to water infiltration
A drainage system should be constructed to collect the most
polluted portion of the storm. In areas where the rate of
evaporation is higher than the rate of precipitation runoff
can be disposed of by evaporation in ponds. Alternatively,
coal pile drainage can be used in processes which tolerate
1 o'w quality waters such as ash handling systems. If the
plant is located near a mine such water can be used in the
coal washers to remove mineral matter. Diversion of this
waste to ash ponds was also considered. However, because
of the low pH of such wastes, coal ash can be leached by
the water resulting in the formation of additional waterborne
pol1utants.
Ai r Pol 1ution Control Scrubbing Devices. The non-
recovery scrubbing process for S02_ removal from flue gas is
also a source of wastewater as the system may be periodically
bled to remo've spent solvent. This is a closed-loop type
system employing recycled lime scrubbing liquor. The process
requires makeup water for saturating the boiler gases.
Changing to S02^ recovery systems would reduce the discharge
from this part of the process as well as allow a credit for
the sale of recovered sulfur dioxide or other sulfur products.
Table VII-6 lists some of the 502^ recovery processes currently
available. It should be emphasized, however, that some of
the listed processes have reached only the pilot plant stage
of their development and cost estimates for their installation
and operation are somewhat higher than those for the non-
recovery processes.
Materi al Substitution
The blowdown from a recirculating cooling system can be
reduced by increasing the concentration cycle. This can be
achieved by substituting scale-forming ions with more soluble
ions, or by using sequestering agents such as polyolesters
and phosphonates to prevent deposition of precipitated solid
phases. These dispersing agents, however, become pollutants
in the blowdown water.
VII-19
-------
Process
1. Double alkali
system
2. Chemilbau
system
~ 3.
f>0
o
Table VI1-6. RECOVERY PROCESSES FOR FLUE GAS DESULFURIZATION SYSTEMS
Mode of 502^
Sorbent System Removal Sulfur Recovery Product
Hydrogen sulfite
system
4. Wellman-Lord
system
5. Cat-Ox^ system
6. Shell flue gas
system
Aqueous solution of Chemical
Sodium hydroxide, absorption
Sodium sulfate, & oxides with
sodium bisulfite CA(OH)2
Precipitation of
dissolved sulfur
Fluidized bed of
activated carbon
solution of sodium
citrate, citric
acid and sodium
thiosulfate
Aqueous solution
of sodium sulfate
and sodium
bisulfite
A bed of cupric
oxide supported by
activated
alumina
Catalytic oxidation Thermal stripping
to H2S04 with hydrogen at
and physical 1000°F and
absorption
Calcium
Calcium
Sulfur,
S02
sulfate
sulfite
liquid
catalytic
with H2S
reduction
Chemical
absorption
Chemical
absorption
Catalytic
oxidation of
SQ2 to S03 with
01 at 850°F
(vanadium oxide)
Oxidation to
cupric sulfate
Precipitation of
dissolved sulfur
with H2S
Thermal
regeneration by
vacuum and
catalytic reduction
with natural gas
Sulfur
o
73
Sulfur
78% sulfuric acid
Concentrated
S02
-------
DRAFT
Lime softening of cooling water makeup prior to its introduction
into the system would also increase the concentration cycle,
though it may be costly because of large volumes of water
requiring treatment.
Installation of plastic or plastic-coated system components
would reduce the extent of treatment of cooling water makeup.
Plastic exhibits considerable resistance to corrosion and
erosion. Many new installations using cooling towers employ
plastic.
Where publicly-owned treatment plants containing a tertiary
step are used, phosphate and nitrate based corrosion inhibitors
could be substituted for chromates as these pollutants are
removed by a tertiary treatment step. Chromate-based compounds
can also be substituted by a recently developed synthetic
organic corrosion inhibitor which is not as toxic as chromate
to microorganisms. The synthetic organic compound reduces
both scaling and fouling as well as inhibits corrosion (12).
Film-forming sulfophosphated organic corrosion inhibitor has
also been developed. The substance is effective in both
fresh and salty water, and is also considerably less toxic
than chromate (12).
To reduce the amount of metals in wastewater from cooling
system blowdown and from chemical cleaning operations,
boilers and condenser cooling systems could be constructed
of non-polluting materials. Tubes and piping could be made
of special alloy metals or coated so as to reduce corrosion
and scaling, but this can be prohibitively costly. Cooling
towers can be constructed out of concrete and ceramic
materials and thus reduce the need for additives to the
cooling water system. Pollutants contained in fireside wash
can be modified by switching fuels. The switch from coal to
low-sulfur oil is an example of such modification.
Switching to low sulfur fuels can also eliminate the need
for air pollution control devices. Switching to gaseous and
liquid fuels eliminates the problems of ash disposal and
coal pile runoff waters.
Hater Conservation and Wastewater Reuse
Different water uses in the plant require water of widely
varying quality. These range from the almost zero solids
requirements for boiler feedwater makeup to the almost
unlimited solids allowed for ash transport water or scrubber
water supply. Consequently, the wastewater produced in the
plant also vary widely in quality. This opens many opportunities
for wastewater reuse.
VII-21
-------
DRAFT
Cooling system blowdown can be reused for ash transport or
as scrubber water supply. Boiler blowdown water is usually
better than the feed water supply and can be reused in
the plant for other purposes.
Boiler blowdown can be reduced by installing a heat recovery
system. In such a system the blowdown is discharged into a
flash tank operating at a lower pressure than the boiler
pressure. Because of the reduced pressure a portion of the
blowdown water evaporates to form low pressure steam which
can be condensed and reused as boiler feedwater. The
reduction in blowdown that can be achieved by this method
depends on the pressure difference between the boiler and
the flush tank. The use of a heat recovery system for
boiler blowdown will also increase the thermal efficiency of
the plant.
Spent regenerants and rinses from the ion exchange system
are also of a quality suitable for many purposes, where
dissolved solids are not a limiting factor.
Some of the periodic waste streams could be recycled or
reused if sufficient storage is available to hold these
streams until needed. Metal cleaning wastes after pre-
treatment or treatment could be used for low quality water
uses such as ash transport or scrubber supply. However, the
cost of storage may make such reuse prohibited.
Materi als Recovery
Nearly all chromates, used as corrosion inhibitors, can be
recovered using properly designed ion-exchange beds.
Regenerant streams from the beds, which contain a relatively
high concentration of chromate, can be returned to the
cooling system as a usable corrosion inhibitor. Plants which
soften boiler feedwater with lime can reuse lime sludge in
their air pollution control system for S02^ removal.
Recoverying .heat from boiler blowdown would reduce thermal
discharges from this segment of the process, as well as
increase the thermal efficienty of the process. Recycling
of fly ash back to the furnace can be employed to increase
thermal efficiency by burning products of incomplete
combustion. It is also possible to recover vanadium from
oil ash with high vanadium content. Spent regenerants from
ion exchange system can be used where the quality of the
acid and alkaline solutions is not critical. For example,
the acid solutions can be used in recirculating cooling
system to maintain the pH of the water below saturation.
Air pollution control devices, on the other hand, may require
an alkaline source of water.
VII-22
-------
DRAFT
Good Housekeeping Practi ces
There are numerous alternative methods ranging from taking
precautionary measures against spills of chemical solutions
or oil to pump sealing to prevent leaks. Facilities should
be constructed so that oil and grease contaminated water
will not drain directly into other water systems or be
diluted by rainfall runoff. Cleaning up oil spills, maintaining
equipment to minimize leaks, and supporting an effective
surveillance program will also minimize contamination of
wastewater effluents. Controlling additions of chemicals
to waters used in the various units of the process would
reduce their concentrations in the effluents streams. Flow
of water into the plant should be regulated in accordance
with production rate.
SUMMARY
A variety of wastewater control and treatment technologies
are available for the steam electric power industry. Since
the water needs, and the requirements for wastewater discharge
are specific to each individual plant, each control and
treatment system must be developed in accordance with the
individual plant requirement and should be integrated in a
comprehensive water management program. Special consideration
should be given to in-process control techniques. Often,
such technique can be found easy and inexpensive to implement
and yet, they can result in substantial reduction in water
consumption and wastewater discharge.
VII-23
-------
DRAFT
SECTION VIII
COST, ENERGY, AND OTHER NONWATER
QUALITY ASPECTS
INTRODUCTION
This section discusses cost estimates for control and
treatment technologies described in previous sections,
energy requirements for these technologies, and nonwater
quality related aspects such as reuse of water within the
plant. Ultimate disposal of brines and sludges, effect of
land availability, user charges and pollutants limitations
Imposed by POTWs and other factors relating to the steam
electric power generating point source category are also
discussed in this Section.
Costs are developed in greater detail for those waste
sources which potentially are discharged to POTWs and are
therefore subject to pretreatment requirements. These
include the following:
» Low Volume Wastes
t Metal Cleaning Wastes
• Cooling Tower Slowdown
• Area Runoff and Ash Pond Discharges
Other waste streams such as ash transport water, boiler
blowdown, and once-through cooling water are provided in
the latter part of this section.
The raw waste characteristics for discharges to POTWs are
similar to those for direct discharge to surface water, as
covered in the Development Document for this industrial
category.
VIII-1
-------
DRAFT
For most power plant wastes, the pretreatment for discharge
to POTW involves control of three parameters of pollution,
pH, suspended solids, and oil and grease. Control of pH
neutralizes any undesirable acidity or alkalinity.
Treatment for suspended solids then removes suspended
metals as well as other suspended material. Oil and grease
is separated from the water phase of the low volume wastes
and skimmed off.
COST REFERENCES ANJJ RATIONALE
Cost information contained in this report was obtained from
the following sources:
• Engineering estimates based on published cost
data for equipment, construction, and
installation;
• Estimates and guidelines for estimating
contained in the Development Document
for steam electric industry discharges to
surface water and the other EPA documents;
• Quotations for materials and supplies
published in current trade journals.
0 Cost,data obtained as a result of direct
inquiry to industry for data on actual
installations.
Interest R ates and Equi ty Finance Charges
Capital investment cost estimates for this study have been
based on 10 percent capital cost which represents a
composite value for either interest rate paid or the
required return on .i n ves tment.
Time Basis for Cost Adjustment
All estimated costs are taken from July, 1976 prices or
where necessary adjusted to this time basis using the ENR
construction cost index of 2413 (July 1, 1976).
Useful Service Life
The useful service life of all wastewater treatment and
disposal facilities is a function of the process involved,
the quality of the equipment and design, its use patterns,
the quality of maintenance and several other factors.
Whereas individual companies often use service lives based
on actual local experience, for the purpose of internal
authorization, the Internal Revenue Service provides
VIII-2
-------
DRAFT
guideline for tax computational purposes which are intended
to reflect approximate average life experience.
The following useful service life values were chosen for use
in this report from the literature, discussions with
representatives of industry, and IRS guidelines data:
• General process equipment 10 years
• Buildings, sewers, ponds, etc. 20 years
o Material handling equipment and 5 years
vehicles
Depreciation
The allocation of the cost of capital assets such as
treatment and disposal equipment less salvage (if any) over
the estimated useful service life of the unit or facility in
a systematic and rational manner as a non-cash expense is
termed depreciation. For IRS tax purposes and to make
suitable financial allowance for equipment replacement
several types of depreciation are used. Simple straightline
depreciation was used as the basis of calculations in this
report.
Capi tal Costs
Capital costs have been defined for this study as all
initial out-of-pocket cash expenditures for provision of
wastewater treatment and disposal facilities. These costs
will include research, development, and feasibility studies
necessary to characterize and design the facilities land and
site preparation costs when applicable, equipment, construction
installation, and start-up costs, costs of buildings,
services and engineering (allocated where necessary),
contractor profits and contingency costs if such exist.
Annual Capi ta 1 Costs
Most capital costs are accrued during the year or two prior
to actual use of the facility. This present worth sum can
be converted to equivalent uniform annual disbursements over
the life of the facility by utilizing the Capital Recovery
Factor Method:
Uniform Annual Disbursement = (P) (i ) (1 +.i) n
(l-M)n-l
where P = present value (capital expenditure),
i = interest rate, %/100
n = useful 1i fe i n years
VIII-3
-------
DRAFT
Operati ng Expenses
Annual costs of operating pretreatment facilities include
labor, supervision, materials, maintenance, taxes, .insurance,
and power and energy. Operating costs combined with
annualized capital costs give total costs for pretreatment
operations.
Rati onale for Model PI ants
Plant costs are estimated for model plants rather than for
any actual plant. Model plants are defined to have sizes of
25 MW and 500 MW capacity, which are representative of large
and small-sized operation.
Definition of Levels of Treatment a-nd Control
Costs are developed for various types and levels of technology:
Minimum (A or basic level ). That level of technology which
is equalled or exceeded by most or all of the involved
pi ants.
Usually, money for this treatment level has already been
spent (in the case of capital investment) or is being spent
(in the case of operating and overall costs).
B,C,D--Leve1s. Successively greater degrees of treatment
with respect to critical pollutant parameters. Two or more
alternative treatments are developed when applicable.
Basi s for Pretreatment Costs
In development of cost estimates found in Tables VIII-1,
VIII-2, VIII-4, and VIII-5, it is assumed that only the
following wastewater effluents are discharged to POTWs and
may, therefore, require pretreatment.
• Low Volume Wastes
• Metal Cleaning Wastes
• Cooling Tower Slowdown
• Area Runoff and Ash Pond Discharges
«
Low volume wastes include ion-exchange regenerants, spills,
leaks, air pollution control system bleed offs, area
washdowns, and other miscellaneous wastewater streams.
Metal cleaning wastes include tube and fireside boiler
cleaning products, as well as air cleaner wastes.
VIII-4
-------
DRAFT
Area runoff includes rainwater runoff from coal piles.
Ash pond overflows and blowdowns are designated as
discharges.
Costs have been addressed separately for the following wastes:
• Ash Transport Water
• Boiler Slowdown
Reasons for addressing these sources of wastes separately
are discussed in detail in Section VII, but are also
discussed briefly below.
Ash transport water from coal-fired plants is generally
recirculated after sedimentation, and the purpose of
sedimentation is process rather than pollution control.
Overflows from ash ponds are included in the wastewater for
pretreatment.
Boiler blowdown can be, and sometimes is
without pretreatment. In can be handled
plant without incremental costs.
discharged to POTW
at the combined
No plant contacted in this study was found to discharge
once-through cooling water to a POTW. Therefore, costs are
not generated for pretreatment requirements.
Cost Variances
The effects of age, location, and size on costs for
treatment and control have been considered and are in
body of this section.
COSTS FOR PRETREATMENT
the
Waste types covered in this subsection include low volume
wastes, metal cleaning wastes, cooling tower blowdown, area
runoff and ash pond discharge. Since the wasteload differs
depending on the fuel source used, cost estimates for
pretreatment of wastewater effluents from steam electric
plants have been divided into those plants burning gas or
oil and those using coal.
011 and Gas Fired Plants
Oil and gas-fired plants probably will have no ash pond
discharge, no air pollution control wastewater, or coal pile
runoff. Therefore, these plants have essentially ion-exchange
VIII-5
-------
regenerants, miscellaneous low volume wastes, cooling tower
blowdown and metal cleaning wastes.
Estimated wastewater volumes in liters/day (GPD) for the
plant sizes given are:
25 MW Plant 500 MW Plant
• Low Volume Wastes
Ion-exchange re
generants 11,400(3000) 454,000(120,000)
Miscellaneous 3,800(1000) 151,400( 40,000)
• Metal Cleaning
Wastes 380( 100) 10,200( 2,700)
t Cooling Tower
Blowdown 94,600(25,000) 1,892,000(500,000)
The low volume wastes contain primarily acids and/or bases
and perhaps some oil. The metal cleaning wastes contain
acids, bases, metals, oil and grease, and suspended solids.
Cooling tower blowdown may contain chromates, chlorine,
chlorinated phenols, mercury, phosphate, zinc and many other
additives commonly used in cooling tower systems. For
purposes of cost analysis, however, cooling tower blowdown
is assumed to contain only free chlorine (chlorine is the
most commonly reported biocide used).
Defined Pretreatment Levels
The raw wastes requiring pretreatment prior to POTW disposal
are similar to those described in the Development Document
for direct dischargers, and use has been made of the data on
wastewater volumes, waste loads and other information
contained therein. The minimum pretreatment level, defined
as Level A, consists of that level of technology which is
equalled or exceeded by most or all of the existing plants.
This level involves some flow equalization and combining of
wastes to get the benefit of some neutralizing and diluting
effects. Expenditures, both capital and operating are small.
VIII-6
-------
DRAFT
TABLE VIII-1
WASTEWATER TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL PLANT
SUBCATEGORY
PLANT SIZE
PLANT AGE
Oil or Gas Fired Plant
25
PLANT LOCATION
COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATE80RY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATI.V9 AND MAINTENANCE
COSTS (EXCLUDINO EFEK3Y AND POWER)
ANNUAL CNEKCY AMD POWER COSTS
TOTAL ANNUAL COSTS
COSTS il) Mils/KWH*
COSTS (13 TO ATTAIN LEVEL
A
10,000
$1,600
Small
Small
1,600
0.008
B
50,000
8,150
10,000
Small
18,150
0.097
c
60,000
9,760
13,000
500
23,260
0.124
D
120,000
19,500
15,000
500
35,000
0.186
E
*Plant operating at full capacity and 7500 hrs/yr.
RESULTINt WASTE-LOAD CHARACTERISTICS
PARAMETER
(a) TSS
Fe
Cu
PH
Oil & Grease
(b) Free CL2
CONCENTRATION (mg/l)(|*in)
RAW
(UN-
TREATED)
300
200
1.0
_ _ __
0.5
AFTER TREATMENT TO LEVEL
A
300
200
1.0
— — __
0.5
8
300
200
1.0
6-9
100
0.5
c
100
< 1.0
< 1.0
6-9
< 100
0.5
D
<100
<1.0
<1.0
6-9
<100
0.0
E
(a) Low volume and metal cleaning wastes combined
(b) Cooling Tower Slowdown
NOTE: TSS, Fe, and Cu, raw wastes concentrations estimated from Table A-V-20
of Development Document EPA 440/1-74029 a (12)
Level A - Flow Equalization
Level B - Equalization of low volume wastes, followed by neutralization
to pH 6-9, skimming of surface oil. Metal cleaning wastes combined
with low volume wastes and neutralized without sludge removal.
Level C - Same as Level B except metal cleaning wastes neutralized, clarified
with sludge removal and discharged.
Level D - Equalization, pH adjustment, oil skimming, clarification, reacidi-
fication. Cooling tower blowdown treated with sulfite.
VIII-7
-------
DRAFT
TABLE VI11-2
WASTEWATER TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL PLANT
SUBCATEGORY
PLANT SIZE
PLANT AGE
Oil or Gas Fired Plant
500 MW
,YEARS
PLANT LOCATION
COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AMD MAINTENANCE
COSTS (EXCLUDIN8 ENER9Y AND POWER)
ANNUAL ENER«Y AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS <»• Mils/KWH*
COSTS (|) TO ATTAIN LEVEL
A
80.000
13,000
Small
Small
13,000
0.004
B
300,000
48,800
60,000
1,000
109,800
' 0.029
c
300,000
48,800
80,000
2,000
130,800
0.035
0
700,000
114,000
130,000
3,000
247,000
0.065
E
*Plant operating at full capacity and 7500 hrs/yr.
RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
(a) TSS
Fe
Cu
nH
Kn
nil & Rrpa<;p
(b) Free CL?
RAW
TREATED)
300
200
1.0
0.5
A
300
200
1.0
0.5
CONCENTRATION
AFTER
B
300
200
1.0
6-9
inn
0 5
(mg/l) (pom)
TREATMENT TO I
C
100
<1.0
<1.0
6-Q
< inn
0.5
.EVEL
0
<100
<1.0
<1.0
6Q
-y
-------
DRAFT
Level B pretreatment involves equalization of low volume
wastes, neutralization to a pH 6-9 and skimming of surface
.oil. Metal cleaning wastes are stored in a large tank or
small pond and fed slowly to the neutralization tank for
small volume wastes and boiler blowdown. There is no
sludge removal on pretreatment of cooling tower blowdown.
Level C pretreatment is the same as Level B except that
the metal cleaning wastes are neutralized, clarified
and discharged. Provision is made for sludge removal.
Level D pretreatment is essentially that for BPCTCA for
direct discharge to surface water. For this level all waste
streams with exception of the cooling tower blowdown are fed
into a tank for pH adjustment (optimum in the 9-11 pH
range), oil is skimmed from the liquid surface, and
suspended solids are removed in a clarifier. Acid is then
added to reduce pH to 6-9 prior to discharge. Cooling tower
blowdown is treated separately with sulfite to remove free
chlorine.
Costs and estimated effluent concentrations achieved for oil
and gas-fired plants are given in Table VIII-1 and VIII-2.
Detailed model description for Level D is given in the
foil owing subsection.
Costs for Levels A, B, and C are roughly estimated from cost
experience with similar wastewater volumes and compositions
in other industries as well as from steam electric power
plants.
Capital cost data for wastewater pretreatment facilities for
oil and gas-fired steam electric power plants discharging to
public sewerage systems are summarized in Table VIII-3.
Table VIII-3. SUMMARY OF CAPITAL COSTS OIL AND GAS-
FIRED PLANTS 25 MW PLANT
t
w
t
0
i
egor
Vol
al C
1 ing
1 er
y
Pretrea
ume Wastes
leaning
Tower B
Bl owdown
Wastes
1 owdown
$
Per KW
tment Tec
0
0
A
.38
.02
NT
NT
IGC
hnol
1
0
ogy
B
.20
.80
NT
NT
Level
1
1
r
.20
.20
NT
NT
1
1
1
0
D
.60
.0
.66
.54
TOTAL COST 0.40 2.00 2.40 4.8
VIII - 9
-------
DRAFT
Table VIII-3. (CONT'd)
500 MW Plant
$ Per KW IGC
Pretreatment Technology Level
Category
Low Volume Wastes
Metal Cleaning Wastes
Cooling Tower Slowdown
Boiler Slowdown
TOTAL COST
D
0.15
0.01
NT
NT
0.50
0.10
NT
NT
0.50
0.10
NT
NT
0.79
0.20
0.31
0.10
0.16
0.6
0.6
1.40
Note: NA not applicable to discharge to POTW
NT Not treated
A - Flow equalization.
B - Equalization and neutralization of low
volume wastes to pH 6-9, skimming of
surface oil. Metal cleaning wastes
combined with low volume wastes and neutralized
without sludge removal.
C - Same as Level B except metal cleaning
wastes neutralized, clarified and
discharged. Provision is made for sludge
removal.
D - Equalization, pH adjustment, oil skimming,
reacidification , clarification. Cooling
tower blowdown treated with sulfite.
Coal-Fired Plants
Coal-fired plants have ash pond discharges, air pollution
control wastewater, coal pile runoff, ion-exchange
regenerants, miscellaneous low volume wastes, cooling tower
blowdown and metal cleaning wastes.
Estimated wastewater volumes in liters/day (GPD) for the
plants sizes given are:
Low Volume Wastes
- Air Pollution Wastes
- Ion Exchange Regenerants
- Miscellaneous
Metal Cleaning Wastes
25 MW 500 MW
3800 (1000) 151,400 (40,000)
11400 (3000) 454,000 (120,000
3800 (1000) 15,400 (40,000)
380 ( 100) 10,200 ( 2,700)
VIII-10
-------
DRAFT
t Cooling Tower 94,600(25000) 1,892,000(500,000)
Blowdown
t Area Runoff 3,800( 1000) 94,600( 25,000)
• Ash Pond Discharge 3,800( 1000) 75,700( 20,000)
The low volume wastes contain primarily acids bases and
suspended solids. The metal cleaning wastes contain acids,
bases, metals, and suspended solids. Cooling tower blowdown
as discussed for oil and gas-fired plants may contain a
variety of additives but for purposes of this cost
development is assumed to contain only free chlorine. Area
runoff contains acid, suspended solids and possibly some
metals. Ash pond discharges contain suspended and dissolved
solids.
The minimum level for pretreatments, defined as Level A,
consists of that level of technology which is equalled or
exceeded by most or all of the existing plants. This level
involves some flow equalization and neutralization resulting
from the combination of waste streams of differing pH.
There is no control or treatment of runoff. Expenditures,
both capital and operating are small.
Level B pretreatment involves equalization of low volume
waste streams, neutralization to pH of 6-9. Metal cleaning
wastes are stored in a large tank or small pond and fed
slowly to the treatment system for low volume wastes.
There is no control of area runoff.
Level C pretreatment is the same as Level B except that
the metal cleaning wastes are neutralized, clarified and
discharged. Provision is made for the sludge removal.
Level D pretreatment involves technology that will in
general meet the requirements of BPCTCA for direct discharge
to surface water. For this level area runoff from coal
piles and ash transport water overflow are retained in a
pond and fed continuously to a central pretreatment system.
Metal cleaning wastes are similarly retained and fed
continuously to the system. The pretreatment system itself
is described in a following subsection. It consists
primarily of a tank for pH control and oil skimming and a
clarifier for suspended solids removal.
VIII-11
-------
DRAFT
Costs and effluent quantities for the four treatment levels
for coal-fired plants are summarized in Tables VIII-4 and
VIII-5. Costs for Level D are developed in a following
subsection.
Capital cost data for wastewater pretreatment facilities for
coal-fired steam electric power plants discharging to public
sewerage systems are summarized in Table VIII-6.
Pretreatment Plants - Level D Technology
Model pretreatment plant costs have been developed for power
plants of 25 MW and 500 MW capacity of combined pretreatment
facilities for low volume and metal cleaning wastes.
Separate cost estimates are presented for treatment of area
runoff and ash transport water discharge.
Estimates are for national average costs and do not consider
regional differences in construction costs. All estimates
are based on the following technology: pretreatment for pH
adjustment to between 6.0 and 9.0, flow equalization so that
the instantaneous peak discharge does not exceed five times
the monthly average flow rate, reduction of suspended solids
to POTW limitations, and removal of biocides, oil and grease
and metals to levels specified in the effluent limitation
guidelines regulations.
Estimated operating costs are presented for centralized
pretreatment facilities for each model plant size. Operating
costs include labor, fuel and power, chemicals, maintenance,
residue removal and management. Actual operating costs may
vary widely for those shown herein because of variations in
processes, degree of automation, and allocation of joint
1 abor costs .
The model waste treatment plants which form the basis of the
cost estimates are designed to provide Level D treatment for
low volume wastes and metal cleaning wastes from coal-
fired plants. Ash transport water or ash pond overflows are
not included in the cost basis. Combination of cooling
water system blowdown with low volume and metal cleaning
wastes is not desirable, since cooling tower blowdown is a
continuous operation requiring minimal treatment. Low
volume and metal cleaning wastes are intermittently produced
and require flow equalization and more intensive treatment.
Plants discharging cooling water system blowdown to the
public sewer will have to add the cost of required
pretreatment of cooling system blowdown to the cost of the
pretreatment of the low volume and metal cleaning wastes.
VIII-12
-------
DRAFT
TABLE VI11-4
WASTEWATER TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL PLANT
SUBCATEGORY Coal Fired Plant
PLANT SIZE ?5 MW .—__
PLANT AGE YEARS PLANT LOCATION
COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATING AND MAINTENANCE
COSTS (EXCLUDINO ENERQYAND POWER)
ANNUAL ENERSY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS Mils/KWH*
COSTS (I) TO ATTAIN LEVEL
A
20,000
3,250
Small
Small
3,250
0.017
B
75,000
12,200
15,000
Small
27,200
0.145
c
90,000
14,600
18,000
500
33,100
0.176
D
143,000
23,300
20,000
500
46,800
0.249
E
*P1ant operating at full capacity and 7500 hrs/yr.
RESULTIIU WASTE-LOAD CHARACTERISTICS
PARAMETER
(a) TSS
Fe
Cu
nH
pn
n*i 1 fi. Cv^o^co
Ul 1 a uicdbc
(b) Free C12
MAW
(UN-
TREATED)
300
150
0.7
0.5
A
300
150
0.7
0.5
CONCENTRATION
AFTER
B
300
150
0.7
6-9
< 100
0.5
(mg/IHwm)
TREATMENT TO I
C
<100
<1.0
0.7
6-9
<100
0.5
.EVEL
D
< 100
< i.n
0.7
6-Q
^inn
0.0
E
(a) Low volume and metal cleaning wastes combined
(b) Cooling Tower Slowdown .
NOTE- TSS, Fe, and Cu, raw wastes concentrations estimated from Table A-V-^0
of Development Document EPA 440/1-74029 a (12)
Level A - Flow Equalization
Level B - Equalization of low volume wastes, followed by neutralization
to pH 6-9, skimming of surface oil. Metal cleaning wastes combined
with low volume wastes and neutralized without s^qe remova1.
Level C - Same as Level B except metal cleaning wastes neutralized, clarified
with sludge removal and discharged.
Level D - Equalization, pH adjustment, oil skimming, clarification, reacidi-
fication. Cooling tower blowdown treated with sulfite.
VIII-13
-------
DRAFT
TABLE VI11-5
WASTEWATER TREATMENT COSTS AND RESULTING
WASTE-LOAD CHARACTERISTICS FOR TYPICAL PLANT
SUBCATEGORY Coal Fired Plant
PLANT SIZE 500 m
PLANT AGE
PLANT LOCATION
COSTS OF TREATMENT TO ATTAIN SPECIFIED LEVELS
COST CATEGORY
TOTAL INVESTED CAPITAL
ANNUAL CAPITAL RECOVERY
ANNUAL OPERATINO AND MAINTENANCE
COSTS (EXCLUDINO ENER8YANO POWER)
ANNUAL ENEMY AND POWER COSTS
TOTAL ANNUAL COSTS
COSTS Mils/KWH*
A
100,000
16,300
Small
Small
16,300
0.004
COSTS (>3 TO ATTAIN LEVEL
B
350,000
57,000
70,000
2,000
129,000
0.035
c
350,000
57,000
93,100
2,500
152,600'
0.041
D
790,000
128,500
163,800
3,000
295,300
0.078
E
*Plant operating at full capacity and 7500 hrs/yr
RESULTING WASTE-LOAD CHARACTERISTICS
PARAMETER
(a) TSS
Fe
Cu
nH
Pn
Oil A Rrpa^p
(b) Free CL?
RAW 1
(UN*
TREATED)
300
150
0.7
0.5
A
300
150
0.7
0.5
CONCENTRATIOft
AFTER
B
300
150
0.7
fi-Q
100
0.5
1
-------
DRAFT
Table VIII-6. SUMMARY OF CAPITAL COSTS COAL FIRED PLANTS
25 MW Plant
$ Per KW IGC
Pretreatment Technology Level
Category A B C
Low Volume Wastes 0.78 2.00 2.40 2.58
Metal Cleaning Wastes 0.02 1.00 1.20 1.2
Cooling Tower Slowdown NT NT NT 1.66
Area Runoff NT NT NT 0.19
Ash Handling Wastes NT NT NT 0.19
Boiler Blowdown NT NT NT 0.10
TOTAL COST 0.80 3.00 3.60 5.92
500 MW Plant
Category A B C D_
Low Volume Wastes 0.19 0.60 0.60 0.92
Metal Cleaning Wastes 0.01 0.1 0.10 0.2
Cooling Tower Blowdown NT NT NT 0.31
Area Runoffs NT NT NT 0.05
Ash Pond Discharges NT NT NT 0.05
Boiler Blowdown NT NT NT 0.10
TOTAL COST 0.20 0.70 0.70 1.63
NOTE: NA - Not applicable to discharge to POTW
NT - Not treated
LEVELS OF PRETREATMENT
A - Flow Equalization
B - Equalization and neutralization of low volume wastes to
pH 6-9 skimming of surface oil. Metal cleaning wastes
combined with low volume wastes and neutralized without
sludge removal.
C - Same as Level B except metal cleaning wastes neutralized,
clarified and discharged. Provision is made for sludge
removal.
D - Equalization, pH adjustment, oil skimming, clarification,
reacidification. Cooling tower blowdown treated with
sulfite.
VIII-15
-------
DRAFT
Power plants sizes selected for model treatment plants are
25 MW and 500 MW. The 25 MW is typical of the smaller
plants discharging to POTWs and listed in the ERCO survey
sample (18). Eighty-seven and one half percent of all
plants listed and discharging to POTWs have less than 100 MW
IGC, with 37.5 percent having less than 25 IGC. Seventy-six
percent of the generating capacity discharging to POTWs is
in the size range between 250 and 1000 MW , and the 500 MW
plant is considered representative of this large size group.
For the 25 MW model plant it was assumed that pretreatment
would be a batch operation with low volume and metal
cleaning wastes combined. Treatment would consist of
gravity separation (skimming) of oils, followed by lime
precipitation of metals, sedimentation, withdrawal of
sludge, adjustment of pH to a neutral range, and controlled
discharge. Figure VIII-1 is a flow diagram for a small
batch plant. For the 500 MW it was assumed that pretreatment
would be on a semicontinuous basis. Metal cleaning wastes
would be stored in an equalization tank and bled into the
treatment operation at a controlled rate. The treatment
process would consist of oil and grease skimming in the
equalization tank, lime addition in the reactor, sedimentation
and clarification, and final adjustment of pH before
discharge to the public sewer. Sludge from the clarifier
would be dewatered on vacuum filters, with the filtrate
returned to the treatment plant influent. Figure VIII-2 is a
flow diagram of this process.
These model treatment plants provide a level of treatment
consistent with effluent guidelines for direct discharge.
For metal cleaning wastes, the removals of metals are
limited to the minimum solubilities discussed in Section
VII.
Slowdown from the cooling water system is a significant
waste stream not included in the combined pretreatment
plants. Level D pretreatment for discharge to the POTW
consists of dechlorination and pH adjustment. A flow
diagram for accomplishing this pretreatment is shown on
Figure VIII-3.
Cost Variances
Age affects the cost of pretreatment in terms of cost per
unit of power produced primarily because age affects
efficiency and plants with lower effficiency will produce
more wastes per unit of power produced. Plants with lower
efficiency will also have lower utilization and therefore
produce fewer units of power in relation to their installed
capacity.
VIII-16
-------
LIME
ACID
LOW VOLUME WASTES
200 gpd/MW
METAL CLEANING WASTES
4 gpd/MW
BOILER SLOWDOWN
40 gpd/MW
244 gpd/MW
OIL & GREASE
TO SEWER & POTW
SLUDGE
(CaS04)
FIGURE VIII-1. Model Waste Pretreatment Plant 25
For Level D Pretreatment
Generating Facility
-------
DRAFT
CLEANING WASTES (5.4 gpd/MW)
BOILER TUBE-i
BOILER FIRESIDE -
AIR PREHEATER-
5.4 gpd/MW
EQUALIZATION
TANK
OIL & GREASE
LOW VOLUME WASTES (320 gpd/MW)
WATER TREATMENT-
AIR POLLUTION CONTROL-
FLOOR DRAINS-
•LABORATORY'S SAMPLING.
1
LIME
REACTOR
330 gpd/MW
ACID
CLARIFIER
330 gpd/MW
FILTER
SEWER TO
POTW
FIGURE VIII-2. Model Waste Pretreatment Plant 500 MW
Generating Facility for Level D Pretreatment
VIII-18
-------
DRAFT
Si ze
Size is related to age in that the older plants are more
likely to be smaller than the newer plants. This relation
is shown in detail in the Development Document (14).
Size affects the cost of pretreatment as shown by the
two plant sizes, 25 MW and 500 MW.
Location
Location affects costs of pretreatment because of
differences in construction costs and labor rates in
various parts of the U.S. and because the choice of the
treatment technology and the cost of providing that
technology are related to the availability of land. For
plants discharging to public sewers, it may be assumed
that they are located in urbanized areas, where land
availability is somewhat limited. The extent of that
limitation will vary widely depending on the size of
the urban area, the location of the plant in that area,
and the location of the area within the U.S. Cost
estimates are presented for two cases, (1) where tankage
can be constructed at ground level, and (2) where
tankage must be supported on a steel framework over
existing facilities because no other land is available.
COST ESTIMATES
Low Volume and Metal Cleaning Wastes
Low volume wastes include all wastewaters other than those
for which specific effluent limitations have been established
Waste sources include wet air pollution control systems,
water treatment systems, laboratory and sampling streams,
floor drainage, cooling tower basin cleaning, and blowdown
from service water systems. For the purpose of cost
estimating, metal cleaning wastes have been combined with
low volume wastes as the most cost effective method of
handling these two waste sources. Pretreatment cost
allottment to each type of waste has been estimated and is
given in Table VIII-7.
VIII-19
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DRAFT
Level erf Treatment
Level D treatment consists of retention, skimming,
pH adjustment for precipitation and readjustment before
discharge and removal of sludges. Level D treatment
meets the requirements of BPCTCA for direct discharge.
Capital Costs
The following table presents estimates for capital costs
of pretreatment plants for Level D treatment of low
volume and metal cleaning wastes, where sufficient land
is available to construct all facilities at ground level
TABLE VIII-7
ESTIMATED CAPITAL COSTS
CHEMICAL WASTES PRETREATMENT PLANT
"""" Installed Generating Capacity
Description 25 MW 500 MW
Equalization Tank - $115,000
Reactor - 25,000
Clarifier $35,000 55,000
Vacuum Filter - 55,000
Pumps 4,000 12,000.
Piping 5,000 15.000
Subtotal, major equipment $44.000 $277,000
Installation & foundations 22,000 138,500
Instrumentation 8,800 55,500
Subtotal, construction costs $74,800 $471fOOO
Engineering & contingencies 22,000 141,000
TotaL landnot limited $97,000 $612,000
Premium for limited land construction 28,000 180,000
Cost, per KW IGC $ 3.78 $ 1.12
Limited land premium 1.12 0.36
Estimated Cost Allottment, Unlimited and
Low Volume Wastes 2.58 0-92
Metal Clean ing Wastes 1.20 0.20
VIII-20
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DRAFT
If land availability is limited, treatment plant components
may have to be stacked vertically and tankage supported
on steel framework. This would double the cost of the
installation of the equipment. It would increase the
total capital cost of the pretreatment plant for the
25 MW generating facility, to $5.00 per KW KGC. For the
500 MW facility, the respective costs would be $792,000
and $1.58 per KW IGC.
Operating Costs
Operating costs include labor; fuel, power and other
utilities; supplies (principally chemicals); maintenance;
removal and disposal of residues; and management.
Assumed unit costs for basic parameters of operating costs
are shown in the following table.
Table VIII-8. ASSUMED UNIT COSTS
Labor, per hour,
including fringe benefits $8.50
Electricity, per kwh 0.04
No. 2 Fuel oil, per MM Btu 2.50
Chemicals
Lime, per ton 30.00
Sulfuric Acid, per ton 50.00
The following table shows operating costs for the combined
pretreatment of low volume and metal cleaning wastes in
treatment plants of the type described in this report.
Annual costs are calculated on the basis that the generating
facility is operated as a base load plant operating 8000
hours per year with each boiler cleaned once per year.
VIII-21
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DRAFT
TABLE VIII-9
OPERATING COSTS-PRETREATMENT OF
LOW VOLUME AND METAL CLEANING WASTES
Items
Operating Labor
Maintenance
Utilities
Water
Electric Power
Sewer Charge
Chemicals and
Supplies
Total
Installed Generating Capaci
(1)
(2)
(3)
(4)
(5)
(6)
Anriual production, KWH
Unit cost, mils per
At .90 capacity
KWH
factor
25 MW(7)
$1,700
3,000
200
40
500
15.000
$20,440
2.0xl08
0.1
500 MW(8)
$17,000
18,000^
2,000
2,400
20,000
101,000
$160,400
4.0xl09
0.04
Notes to Table VIII-9
(1) 25 MW Plant - 4 hrs/wk 200 hrs/yr
500 MW Plant - 40 hrs/wk 2000 hrs/yr
(2) 3% of capital cost
(3) City water @ .60/100 gall
(4) 25 MW Plant - 5 kwh x 200 hrs
500 MW Plant - 30 kwh x 2000 hrs
(5) Sewer service charge @ .30/1000 gal
(6) Lime 500 mg/1
Sulfuric Acid 100 mg/1
(7) Design flow: Low volume wastes: 5,000 gpd (from DD)
Metal cleaning wastes: 25,000 gallons batch
(8) Design flow: Low volume wastes 200,000 gpd (from DD)
Metal cleaning wastes: 500,000 gallons batch
VIII-22
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DRAFT
Ash Transport Water
Ash transport water is the water used in the hydraulic
transport of bottom or fly ash. Since the water serves
only as a carrier of the ash, water quality is not a
significant consideration. As a matter of fact, a high
level of suspended solids is desirable since it facilitates
the subsequent settling out and removal of the ash.
Settling basins are a normal component of ash transport
systems. They may be either of the mechanical clarifier
or natural lagoon (ash pond) type. Wet ash is removed
from the clarifiers and disposed off site. The supernatent
water is recycled to the process. The only routine blowdown
from the system is the water removed with the wet ash.
Waste streams result from overflows during periods of
precipitation and for intermittent blowdown purposes.
At one of the plants visited, blowdown from a recirculating
water system used to transport fly ash from oil fueled
boilers was discharged to the POTW. This waste can be
combined with area runoff and could be treated together.
Costs for pretreatment of discharges from ash transport
systems are estimated from the volume of the portion
coming to the retention pond.
Metal Cleaning Wastes
Metal cleaning wastes include wastes from the cleaning of
the inside (waterside) of the boiler tubes, usually done
by chemical means, and the outside (fireside) of the
boiler and air preheater surfaces, usually done by
mechanical means. Cleaning is done about once per year
for each generating unit during a period when the unit
is not in generating service. The wastes are discharged
during a few hours over a two-day period and contain high
concentrations of suspended solids, chemicals used in the
cleaning process, and metal and other residues removed
from the surfaces being cleaned.
VIII-23
-------
DRAFT
Level of Treatment
Level D treatment consists of retention, skimming, pH
adjustment to specific levels to precipitate various metals,
removal of sludges, and readjustment of pH for discharge.
Costs
The combined model treatment plants for low volume wastes
have been sized to handle metal cleaning wastes as well.
Costs for pretreatment of metal cleaning wastes are
therefore included in the cost of pretreatment for low
volumes.
Boiler Slowdown
The quality of boiler blowdown is generally higher than
the quality of the raw water source, which for most plants
discharging to POTWs is the municipal water supply. If
boiler blowdown is discharged to the waste stream, it will
tend to dilute the wastes and make any treatment less
efficient. Boiler blowdown should
to the plant service water system,
this is done. Therefore, no costs
pretreatment of this waste source.
Cooling System Wastes
therefore be returned
and in most plants
have been developed for
Cooling system wastes are discharges of water that have
been used to cool the main condenser surfaces. Cooling
systems are either of the once-through or recirculating
type. There are no known plants which discharge
once-through cooling water to a POTW. Recirculating
systems require blowdown which becomes a waste source.
Levels ojf Treatment
Levels A thru C treatment for cooling system blowdown
consists of discharge to the POTW without pretreatment. If
the only biocide or other cooling water treatment chemical
used is chlorine and the POTW does not impose restrictions
on chlorine in discharges to the sewer, cooling water
blowdown may be discharged without pretreatment. In that
VIII-24
-------
DRAFT
case the only costs will consist of the sewer service charges
Level D treatment for residual chlorine consists of
dechlorination and possible pH adjustment and meets the
requirements of effluent limitation guidelines for BPT for
direct discharge. Level D treatment for cooling water
system blowdown is shown in Figure VIII-3.
Capital Costs
Table VIII-10 presents estimates for capital costs of
pretreatment for cooling water system blowdown. These costs
assume that chlorine is used as a biocide, that the POTW
requires removal of residual chlorine, and that no other
biocides or inhibitors unacceptable to the POTW are added to
the, cooling water system.
Operati ng Costs
Operating costs for pretreatment of cooling system blowdown
pretreatment consists of operating labor, maintenance, and
chemicals for dechlorination. They are summarized in
Table VIII-11.
Area Runoff
The area runoff subcategory includes runoff from material
storage.
Coal is stored in open piles and oil is stored in covered
tanks. Materials storage therefore represents a significant
source of waste only for coal-fired plants. And since
the burning of oil produces only about two percent of the
amount of ash produced by the burning of coal, ash ponds
are a feature of coal burning plants primarily. Material
storage wastes from coal piles and ash ponds are therefore
applicable to coal burning plants only.
No plants discharging area runoff to POTWs were found in
the industry survey.
VIII-25
-------
DRAFT
MAKE-UP
COOLING
TOWER
SLOWDOWN (1000
gpd/MW)
r
SULFITE
LIME
\.CID
MONITOR
RESIDUAL
CHLORINE
DH
1
CONTACT TANK
SEWER
FIGURE VI11-3. Cooling Water System Slowdown Treatment
For Level D Pretreatment
VIII-26
-------
DRAFT
Table -VIII-10
ESTIMATED CAPITAL COST
COOLING WATER SYSTEM SLOWDOWN TREATMENT
Description
Contact Tank
Chemical Feed System
Piping
Subtotal, major equipment
Installation & foundations
Instrumentation
Subtotal, construction costs
Engineering & contingencies
Total Cost
Cost per KW IGC
Installed Generating Capacity
25 MW 500 MW
$10,000
4,000
6,000
$20,000
10,000
2,000
$32,000
9,600
$41,600
$ 1.66
$40,000
10,000
25,000
$75,000
37,000t
5,000
$117,000
35,000
$153,000
$ 0.31
TableVIII-n
ESTIMATED OPERATING COSTS
COOLING WATER SYSTEM SLOWDOWN TREATMENT
Description
Operating Labor
Maintenance
Chemicals
Total
Unit costs, mils/KWH
at .90 capacity factor
Installed Generating Capacity
25 MW500 MW
$1,000
1,200
500
$2,700
0.0135
$4,000
6,000
10,000
$20,000
o.ooS
VIII-27
-------
DRAFT
Level D treatment for coal pile runoff and ash pond
overflows consists of neutralization and sedimentation.
Its cost is a function of the size of the catchment area
covered by the coal pile and the ash pond and the design
meteorological conditions at the particular site. The
regulation (40 CFR 423.40) require that treatment
facilities be sized to treat the runoff from a 10-year,
24-hour rainfall event to produce an effluent having
suspended solids of less than 50 mg/1 and a pH between
6.0 and 9.0. The applicable technology consists of
lined ponds capable of holding various volumes of runoff.
Capital Costs
For a 500 MW plant, a coal pile representing 90 days
storage will occupy 10 - 40 acres. A retention basin
designed to provide one hour detention at the maximum
10 minute rate associated with a 10-year, 24 hour storm
will generally meet the effluent requirement. Depending
on location, such a retention basin could cost $27,000,
$96,000, exclusive of land, or $0.05-$0.19 per KW IGC.
Operating Costs
Operating costs for pretreatment facilities for runoff
from coal piles and ash ponds are limited to chemicals
for neutralizing. It is estimated that chemicals for
this purpose would cost $360 per year for a 25 MW plant
and $7,200 per year for a 500 MW plant. This corresponds
to a unit cost of .0018 mils per KWH generated for a
90 percent capacity factor.
The following table (VIII-12) presents estimates for capital
costs of pretreatment plants for Level C treatment of low
volume and metal cleaning wastes for a coal-fired plant
where sufficient land is not available.
ULTIMATE DISPOSAL
Costs For Land Destined Sol id Wastes
Waste treatment processes discussed in this report are
separation techniques which produce a liquid fraction
suitable for discharge to the public sewer or reuse
within the plant and a liquid or solid residue which
requires ultimate disposal. Many of the processes
produce sludges containing between 0.5 and 5.0 percent
solids. These sludges are generally further dewatered
at the site to 15 to 30 percent solids and then disposed
off site. The following paragraphs discuss techniques
and costs of dewatering and ultimate disposal applicable
to steam electric power plants.
VIII-28
-------
DRAFT
Table VIII-12. ESTIMATED CAPITAL COSTS CHEMICAL
WASTES PRETREATMENT PLANT LEVEL C
Installed Generating Capacity
Description 25 MW 500 MW
Equalization Tank $ 28,000 $ 115,000
Reactor 2,000
Clarifier 2,000 5,000
Pumps 1,000 4,000
Piping 2,000 5,000
Subtotal, major equipment I33,000 $131,000
Installation & Foundations 17,000 65,000
Instrumentation 4,000 14,000
Subtotal, construction
costs $ 54,000 $ 210,000
Enginnering & Contin-
gencies 16,000 60,000
Total, land not limited $ 70,000 $ 270,000
Premium for limited land
construction 20,000 80,000
Cost per KW IGC $ 2.80 $ 0.54
Limited Land Premium 0.80 0.16
Estimated cost allottment, unlimited land
Low volume wastes 2.40 0.60
Metal cleaning wastes 1.20 0.10
VIII-29
-------
DRAFT
User Charges For Sewer Service
Of the twenty-two plants visited in this study only
15 percent reported separate charges for sewer service,
while 35 percent reported surcharges on their water bills
for sewer service. Fifty percent did not report charge
for sewer service as they were municipal utilities whose
internal billing systems did not allow for tracking of
such charges.
The average charge for sewer service in this industry is
$0.06/1000 L ($0.23/1000 gal).
Evaporation Ponds
Evaporation ponds are used by the industry as a method of
ultimate disposal, particularly in the arid areas of the
southwestern United States. The extensive land requirements
make it unsuited for use in urban areas where plants
discharging to POTWs are generally located.
Conveyance Off Site
The cost of this method of disposal is entirely related to
the distance between plant and disposal site. Alternate
methods of conveyance are trucks, railroads and pipelines.
Trucking is most economical for distances under 50 miles.
Costs are of the order of ($.01-$0.13 per 1000 liter)
($0.05-$0.50 per 1,000 gallon) miles exclusive of final
disposal charges.
Landfills
Landfills are the most common method of disposal of
solid wastes. Costs of disposal at landfills range from
$1 to $9 per metric ton ($2-10 per ton). Recent federal
regulations require landfills to provide leachate control,
so that soluble components of the wastes cannot cause
groundwater pollution.
VIII-30
-------
DRAFT
ENERGY CONSIDERATIONS
In contrast to the effluent guidelines for thermal
discharges, the promulgation of standards for pretreatment
is not expected to involve significant energy requirements
or to have a measurable impact on the energy production
of the power plant. None of the treatment technologies
described herein affect the power generating cycle and
therefore do not require "retrofitting" to the extent
that the performance of the plant is impaired. None of
the processes involve a change of state and the only
requirements for energy are for possible pumping needs.
Even these needs are site dependent and many power plants
may find it feasible to install the equipment in such a
manner that repumping is not required.
For estimating purposes it has been assumed that a
pretreatment plant handling low volume and metal cleaning
wastes from a 25 MW generating plant would have a connected
load of 5HP and that a similar plant for the 500 MW
generating facility would have a connected load of 30 HP.
Each plant would operate the equivalent of 800 hours per
year, at full connected load. Under these conditions, the
energy consumption by the waste treatment facilities would
constitute about 0.02 percent of the generating capacity
of the 25 MW generating plant and less than 0.01 percent
of the generating capacity of the 500 MW plant.
VIII-31
-------
DRAFT
SECTION IX
PRETREAMENT STANDARDS
"To be Proposed by the Environmental Protection Agency'
IX-1
-------
DRAFT
SECTION X
ACKNOWLEDGMENTS
The preparation of this report was accomplished through the
efforts of the staff of the Environmental Engineering
Department, Hittman Associates, Inc., Columbia, Maryland
under the overall direction of Mr. Burton C. Becker, Vice
President, Operations. Mr. Dwight B. Emerson and Mr.
J. Carl Uhrmacher shared direction of the day-to-day work
on the program.
Mr. John Lum, Project Officer, Effluent Guidelines Division,
through his assistance, leadership, and advice has made an
invaluable contribution to the preparation of this report.
Mr. Lum provided a careful review of the draft report and
suggested organizational, technical and editorial changes.
He also was most helpful in making arrangements for the
drafting, presenting, and distribution of this report.
Mr. Ernest P. Hall, Jr., Assistant Director, Effluent
Guidelines Division and Mr. Harold B. Coughlin, Branch
Chief, Effluent Guidelines Division, Mr. Devereaux Barnes,
and Mr. Elwood Forsht, Project Officers, Effluent Guidelines
Division offered many helpful suggestions during the
program.
Appreciation is extended to the Federal Power Commission,
Washington D.C., and to Mr. Vacys Saulis, Region V
Office of the Environmental Protection Agency, Chicago,
Illinois, to acknowledgment James Ferry-EPA/Office of
Planning and Evaluation Garry F. Otakie-EPA/Office of Water
programs, Theordore Landry-EPA Region I, Fred Roberts
EPA Corvallis, Oregon Environmental Research Laboratory,
Harvey Lunenfeld-EPA Region II, Gary Liberson-EPA Office
of Analysis and Evaluation for assistance and cooperation
rendered to us in this program. Additionally, we wish to
thank Mr. John Rose of Daniel P. Frankfurt, PC, for his
invaluable aid.
Also our appreciation is extended to the staff of the
Environmental Engineering Department of Hittman Associates,
Inc. for their assistance during this program. Specifically,
our thanks to:
Dr. Leon C. Parker, Senior Chemical Engineer
Dr. T. Goldshmid, Environmental Engineer
Mr. J. Carl Uhrmacher, Senior Chemical Engineer
Mr. Roger S. Wetzel, Environmental Engineer
X-l
-------
DRAFT
Ms. Barbara A. White, Manuscript Coordinator
Mr. Craig S. Koralek, Environmental Engineer
Mr. Kenneth G. Budden, Environmental Engineer
Mr. Robert G. Matysek, Junior Chemical Engineer
Mr. Carroll E. Stewart, Chemical Engineer
Mr. Robert T. Brennan, Environmental Engineer
Mr. Efim M. Livshits, Environmental Engineer
Mr. Anthony T. Shemonski , Environmental Engineer
Mr. Werner H. Zieger, Environmental Engineer
X-2
-------
DRAFT
SECTION XI
REFERENCES
1. Barker, P.A., "Water Treatment for Steam Generating
Systems", Industrial Water Engineering, March/April
1975.
2. City Council of Roswell, New Mexico, Ordinance No. 933,
Industri al Waste Ordinance of The City of_ Roswel 1 ,
New Mexi co.
3. Dean, John G., Bosqui, Frank L., and Lanouette,
Kenneth H., "Removing Heavy Metals from Wastewater,"
Environmental Science and Technology, Volume 6,
No. 6, June 1972.
4. Duffey, J.G.,Gale, S.B., and Bruckenstein S.,
"Electrochemical Removal of Chromates and Other
Metals," Cooling Towers, Volume 2, pp. 44-50, 1975.
5. Goldstein, Paul, "Control of Chemical Discharges for
the Steam Electric Power Industry" NUS Corporation,
Pitssburg, PA., Presented at Conference on Water
Quality - Considerations for Steam Electric Power
Plants, Atomic Industrial Forum, Inc., Phoenix, AZ,
January 1975.
6. Nail, Douglas E., "The Influence of EPA Guidelines
on Treatment of Power Plant Wastes," Industrial
Water Engineering.
7. Office of Science and Technology, Electric Power
and the Envi ronment, August 1970.
8. Patterson, J.W., et al , Wastewater Treatment Technology.
Illinois Institute for Environmental Quality, Chicago,
Illinois , August, 1971.
9. Scott, David L., Pollution i_n the Power Industry,
D.C. Heath and Co., Lexington, MA, 1973.
10. Stratton, Charles L., and Lee, G. Fred, "Cooling
Towers and Water Quality," Journal of the Water
Pollution Control Federation, Volume 47, No. 7,
July 1975.
11. Teknekron, Inc., Water Pollution Control erf the
Steam Electric Power Industry - Assessment of the
Costs and Capabil ities erf Water Pollution Control
Technology for the Steam Electric Power Industry,
Volume 1, Berkley, CA, December 1975.
XI-1
-------
DRAFT
12. Teknekron, Inc., Water Pollution Control erf the
Steam Electric Power Industry - Economic Impact of
Water Pollution Control in the Steam Electric
Power Industry, Volume 2, Berkeley, CA, December,
1975.
13. Teknekron, Inc., Water Pollution Control for the
Steam Electric Power Industry - Appendix, Volume 3,
Berkeley, CA, December 1975.
14. U.S. Environmental Protection Agency, Development
Document for Proposed Eff1uent Limitations Gui deli nes
and New Source Performance Standards for the Steam
Electric Power Generating Industry, October, 1974.
15. U.S. Environmental Protection Agency, Office of
Water Program Operations, Pretreatment erf Pol 1 ution
Introduced into Pub!ically Owned Treatment Works
October 1973.
16. U.S. Environmental Protection Agency, Office of
Water Program Operations, State and Local Pretreatment
Programs (Draft Federal Guideli nes) Volume 1, August,
1975.
17. U.S. Federal Power Commission, Statistics of
Publicly Owned Electric Utilities in the United
States 1970. Washington, D.C., February 1972.
18. U.S. Environmental Protection Agency, Office of
Planning and Evaluation, Envi ronmental Assessment
of. Al ternati ve Thermal Control Strategies for the
Electric Power Industry, December 1974.
19. Fair, G.M., Geyer, C.G., and Okun, D.A., Water
and Wastewater Engineering, New York, NY, 1968.
XI-2
-------
DRAFT
SECTION XII
GLOSSARY
Absolute Pressure. The total force per unit area measured
above absolute vacuum as a reference. Standard atmospheric
pressure is 101,326 N/H2 (14.696 psi) above absolute vacuum
(zero pressure absolutej.
Absolute Temperature. The temperature measured from a
zero at which all molecular activity ceases. The volume
of an ideal gas is directly proportional to its absolute
temperature. It is measured in °K (°R) corresponding to
°C + 273 (°F + 459).
Ani on. The charged particle in a solution of an electrolyte
which carries negative charge.
Anthracite. A hard natural coal of high luster which
contains little volatile matter.
Approach Temperature. The difference between the exit
temperature of water from a cooling tower, and the wet
bulb temperature of the air.
Ash. The solid residue following combustion of a fuel.
Ash Sluice. The transport of solid residue ash by water
flow in a conduit.
Backwash. Operation of a granular fixed bed in reverse
flow to wash out sediment and reclassify the granular
medi a.
Bag Filters. A fabric type filter in which dust laden
gas is made to pass through woven fabric to remove the
particulate matter.
Base. A compund which dissolves in water to yield
hydroxyl ions (OH-) .
Base-Load Uni t. An electric generating facility operating
continously at a constant output with little hourly or
daily fluctuation.
XII-1
-------
DRAFT
B i o c i d e. An agent used to control biological growth.
Bituminous. A coal of intermediate hardness containing
between 50 and 92 percent carbon.
B1owdown. A portion of water in a closed system which
is wasted in order to prevent a built-up of dissolved
sol ids.
Boiler. A device in which a liquid is converted into its
vapor state by the action of heat. In the steam electric
generating industry, the equipment which converts water
into steam.
Boiler Feedwater. The water supplied to a boiler to be
converted into steam.
Boiler Fireside. The surface of boiler heat exchange
elements exposed to the hot combustion products.
Boiler Scale. An incrustation of salts deposited on the
waterside of a boiler as a result of the evaporation of
water.
Boiler Tubes. Tubes contained in a boiler through which
water passes during its conversion into steam.
Bottom Ash. The solid residue left from the combustion
of a fuel, which falls to the bottom of the combustion
chamber.
Brackish Hater. Water having a dissolved solids content
between that of fresh water and that of sea water,
generally from 1000 to 10,000 mg per liter.
Brine. Water saturated with a salt.
Bus Bar. A conductor forming a common junction between two
or more electric circuits. A term commonly used in the
electric utility industry refer to electric power leaving
a station boundary. Bus bar costs would refer to the cost
per unit of electrical energy leaving the station.
XII-2
-------
DRAFT
Capacity Factor. The ratio of energy actually produced
to that which would have been produced in the same period
had the unit been operated continously rated capacity.
Cation. The charged particles in solution of an electrolyte
which are positively charged.
Carbonate Hardness. Hardness of water caused by the
presence of carbonates and bicarbonates of calcium and
magnesi urn.
Circulating Water Pumps. Pumps which deliver cooling
water to the condensers of a power plant.
Ci rculati ng Water System. A system which conveys cooling
water from its source to the main condensers and then to
the point of discharge. SYnonymous with cooling water
system.
Clarification. A process for the removal of suspended
matter from a water solution.
C1 a r i f i e r. A basin in which water flows at a low velocity
to allow settling suspended matter.
CIosed Circulating Water System. A system which passes
water through the condensers, then through an articial
cooling device, and keeps recycling it.
Coal Pile Drainage. Runoff from the coal pile as a result
of rainfal1.
Condensate Poli sher. An ion exchanger used to adsorb
minute quantities of cations and anions present in
condensate as a result of corrosion and erosion of metallic
surfaces.
Condenser. A device for converting a vapor into its liquid
phase.
Constructi on. Any placement, assembly, or installation of
facilities or equipment (including contractural obligations
to purchase such facilities or equipment) at the premises
where the equipment will be used, including preparation
work at the premises.
XII-3
-------
DRAFT
Convection. The heat transfer mechanism arising from the
motion of a fluid.
Cooling Canal . A canal in which warm water enters at one
end, is cooled by contact with air, and is discharged at
te other end.
Cooling Lake. See Cooling Pond.
Cool ing Pond. A body of water in which warm water is cooled
by contact with air, and is either discharged or returned
for reuse.
Cooling Tower. A configured heat exchange device which
transfers reject heat from circulating water to the
atmosphere.
Cooli ng Tower Basin. A basin located at the bottom of a
cooling tower for collecting the falling water.
Cooling Water System. See Circulating Water System.
Corrosion I h i b i t o r. A chemical agent which slows down
or prohibits a corrosion reaction.
Counterflow. A process in which two media flow through
a system in opposite directions.
Critical Point. The temperature and pressure conditions at
which the saturated-liquid and saturated-vapor states of
a fluid are identical. For water-steam these conditions
are 3208.2 psia and 705.47°F.
Cycling Plant. A generating facility which operates
between peak load and base load conditions. In this
report, a facility operating between 2000 and 6000 hours
per year.
Cyclone Furnace. A water-cooled horizontal cylinder in
which fuel is fired, heat is released at extremely high
rates, and combustion is completed. The hot gases are
then ejected into the main furnace. The fuel and
combustion air enter tangentially, imparting a whirling
motion to the burning fuel, hence the name Cyclone Furnace.
Molten slag forms on the cyclinder walls, and flows off
for removal.
XII-4
-------
DRAFT
Deaeration. A process by which dissolved air and oxygen
are stripped from water either by physical or chemical
methods.
Deaerator. A device for the removal of oxygen, carbon
dioxide and other gases from water.
D e g a s i f i c a t i o n. The removal of a gas from a liquid.
D e i o n i z e r. A process for treating water by removal of
cations and a n i o n s .
Demineralizer. See D e ionizer.
Demister. A device for trapping liquid entrainment from
gas or vapor streams.
Dewater. To remove a portion of the water from a sludge
or a slurry.
Dew Point. The temperature of a gas-vapor mixture at
which the vapor condenses when it is cooled at constant
humi di ty.
Diesel . An internal combustion engine in which the
temperature at the end of the compression is such that
combustion is initiated without external ignition.
Di scharge. To release or vent.
Di scharge Pi pe or Condui t. A section of pipe or conduit
from the condenser discharge to the point of discharge
into receiving waters or cooling device.
Dri ft. Entrained water carried from a cooling device by
the exhaust air.
Dry Bottom .Furnace. Refers to a furnace in which the ash
is collected as a dry solid in hoppers at the bottom of
the furnace, and removed from the furnace in this state.
Dry Tower. A cooling tower in which the fluid to be
cooled flows within a closed system. This type of tower
usually uses finned or extended surfaces.
Dry He!1. A dry compartment of a pump structure at or
below pumping level, where pumps are located.
XII-5
-------
DRAFT
Economizer. A heat exchanger which uses the heat of
combustion gases to raise the boiler feedwater
temperature before the feedwater enters the boiler.
Electrostatic Preci pi tator. A device for removing particles
from a stream of gas based on the principle that these
particles carry electrostatic charges and can therefore
be attracted to an electrode by imposing a potential across
the stream of gas.
Evaporation. The process by which a liquid becomes a
vapor.
Evaporator. A device which converts a liquid into a vapor
by the addition of heat.
Feedwater Heater. Heat exchangers in which boiler
feedwater is preheated by steam extracted from the
turbine.
Filter Bed. A device for removing suspened solids from
water, consisting of granular material placed in
horizontal layers and capable of being cleaned
hydraulically by reversing the direction of the flow.
Fi1tration. The process of passing a liquid through a
filtering medium for the removal of suspned or colloidal
matter.
Fireside Cleaning. Cleaning of the outside surface of
boiler tubes and combustion chamber refractories to
remove deposits formed during the combustion.
Flue Gas. The gaseous products resulting from the
combustion process after passage through the boiler.
Fly Ash. A portion of the non-combustible residue from
a fuel which is carried out of the boiler by the flue gas.
Fossil Fuel. A natural solid, liquid or gaseous fuel such
as coal, petroleum or natural gas.
Generation. The conversion of chemical or mechanical
energy into electrical energy.
Heat Rate. The fuel heat input (in Joules or BTU)
required to generate a KWH.
XII-6
-------
DRAFT
Heating Value. The heat available from the combustion of
a given quantity of fuel as determined by a standard
calorimetric process.
Humidity. Pounds of water vapor carried by 1 Ib of dry air.
Ion. A charged atom, molecule or radical, the migration
oF~which affects the transport of electricity through an
electrolyte.
Ion Exchange. A chemical process involving reversible
interchange of ions between a liquid and a solid but no
radical change in the structure of the solid.
Lignite. A carbonaceous fuel ranked between peat and coal.
Makeup Hater Pumps. Pumps which provide water to replace
that lost by evaporation, seepage, and blowdown.
Mechanical Draft Tower. A cooling tower in which the air
flow through the tower is maintained by fans. In forced
draft towers the air is forced through the tower by fans
located at its base, whereas in induced draft towers the
air is pulled through the tower by fans mounted on top of
the tower.
Mill. One thousandth of a dollar.
Mine-mouth Plant. A steam electric powerplant located
within a short distance of a coal mine and to which the
coal is transported from the mine by a conveyor system,
slorry pipeline or truck.
Mole. The molecular weight of substance expressed in grams
(or pounds).
Name Plate. See Nominal Capacity.
Natural Draft Cooling Tower. A cooling tower through
which air is circulated by natural or chimney effect.
A hyperbolic tower is a natural draft tower that is
hyperbolic in shape.
Neutralizati on. Reaction of acid or alkaline solutions with
the opposite reagent until the concentrations of hydrogen
and hydroxyl ions are about equal.
XII-7
-------
DRAFT
New Source. Any source, the construction of which is
commenced after the publicated of proposed Section 306
regulati ons .
Nominal Capacity. Name plate - design rating of a plant,
or specific piece of equipment.
Nuclear Energy. The energy derived from the fission of
nuclei of heavy elements such as uranium or thorium or
from the fusion of the nuclei of light elements such as
deuterium or tritium.
Once-through Circulating Water System. A circulating
water system which draws water from a natural source",
passes it through the main condensers and returns it to
a natural body of water.
Overflow. (1) Excess water over the normal operating
limits disposed of by letting it flow out through a device
provided for that purpose; (2) The device itself that
allows excess water to flow out.
Osmosis. The process of diffusion of a solvent thru a
semi-permeable membrane from a solution of lower to one
of higher concentration.
Osmotic Pressure. The equilibrium pressure differential
across a semi-permeable membrane which separates a solution
of lower from one or higher concentration.
Oxidation. The addition of oxygen to a chemical compund,
generally, any reaction which involves the loss of
electrons from an atom.
Packing (Cooli ng Towers). A media providing large surface
area for the purpose of enhancing mass transfer, usually
between a gas or vapor, and a liquid.
Precipitation. A pheonomenon that occurs when a substance
held in solution in a liquid phase passes out of solution
into a solid phase.
Preheater (Air). A unit used to heat the air needed for
combustion by absorbing heat from the products of
combustion.
XII-8
-------
DRAFT
Peak-load Plant. A generating facility operated only
during periods of maximum demand, in this report is is a
facility operating less than 2000 hours per year.
Penalty. A sum to be forfeited, or a loss due to some
action.
Plant Code Number. A four-digit number assigned to all
powerplants in the industry inventory for the purpose
of this study.
Plume (Gas). A conspicuous trail of gas or vapor emitted
from a cooling tower or chimney.
Powerplant. Equipment that produces electrical energy,
generally by conversion from heat energy produced by
chemical or nuclear reaction.
Psychrometric. Refers to air-water vapor mixtures and their
properties. A psychrometric charg graphically displays
the relationship between these properties.
Pulverized Coal. Coal that has been ground to a powder,
usually of a size where 80 percent passes through a
#200 U.S.S. sieve.
Pump Runout. The tendency of a centrifugal pump to
deliver more than its design flow when the system
resistance falls below the design head.
Pyri tes. Combinations of iron and sulfur found in coal as
FeS^.
Radwaste. Radioactive waste streams from nuclear power-
pi ants.
Range. Difference between entrance and exit temperature
of water in a cooling tower.
R a n k i n e Cycle. THe thermodynamic cycle which is the basis
of the steam-electric generating process.
Rank of Coal . A classification of coal based upon the
fixed carbon on a dry weight basis and the heat value.
Recirculation System. Facilities which are specifically
designed to divert the major portion of the cooling water
discharge back to the cooling water intake.
XII-9
-------
DRAFT
Reelrculation. Return of cooling water discharge back to
the cooling water intake.
Regeneration. Displacement from ion exchange resins of the
ions removed from the process solution.
Reheater. A heat exchange device for adding superheat to
steam which has been partially expanded in the turbine.
Relative Humidity. Ratio of the partial pressure of the
water vapor to the vapor pressure of water at air
temperature.
Reinjection. To return a flow or portion of flow, into a
process.
Reverse Osmosis. The process of diffusion of a solvent
thru a semi-perable membrane from a solution of higher to
one or lower concentration, affected by raising the pressure
of a more concentrated solution to above the osmotic
pressure.
Reduction. A chemical reaction which involes the addition
of electrons to an ion to decrease its positive valence.
Saline Water. Water containing salts.
Sampling Stations. Locations where several flow samples
are tapped for analysis.
Sanitary Wastewater. Wastewater discharged from sanitary
conveniences of dwellings and industrial facilities.
Saturated Air. Air in which the water vapor is in
equilibrium with the liquid water at air temperature.
Saturated Steam. Steam at the temperature and pressure at
which the liquid and vapor phase can exist in equilibrium.
Seale. Generally insoluble deposits on heat transfer
surfaces which inhibit the passage of heat through these
surfaces.
Scrubber. A device for removing particles and/or objection-
able gases from a stream of gas.
Secondary Treatment. The treatment of sanitary wastes
water by biological means after primary treatment by
sedimentation.
XII-10
-------
DRAFT
Sedimentation. The process of subsidence and deposition
of suspended matter carried by a liquid.
Sequestering Agents. Chemical compunds which are added
to water systems to prevent the formation of scale by
holding the insoluble compunds in suspension.
Service Mater Pumps. Pumps providing water for auxiliary
plant heat exchangers and other uses.
SJUg Tap Furnace. Furnace in which temperature is high
enough to maintain ash (slag) in a molten state until it
leaves the furnace through a tap at the bottom. The
slag falls into the sluicing water whwere it cools,
disintegrates, and is carried away.
SIimicide. An agent used to destroy or control slimes.
Sludge. Accumulated solids separated from a liquid during
processing.
Softener. Any device used to remove hardness from water.
Hardness in water is due mainly to calcium and magnesium
salts. Natural zeolites, ion exchange resins, and
precipitation processes are used to remove the calcium
and magnesium.
Spinning Reserve. The power generating reserve connected
to the bus bar and ready to take load. Normally consists
of units operating at less than full load. Gas turbines,
even though not running, are considered spinning reserve
due to their quick start up time.
Spray Module (Powered Spray Module). A water cooling
device consisting of a pump and spary nozzle or nozzles
mounted on floats and moored in the body of water to be
cooled. Heat is transfered principally by evaporation
from the water drops as they fall through the air.
Station. A plant comprising one or several units for the
generation of power.
Steam Drum. Vessel in which the saturated steam is
separated from the steam-water mixture and into which the
feedwater is introduced.
XII-11
-------
DRAFT
Supercritical. Refers to boilers designed to operate at
or above the critical point of water 22,100 kn/m2 and
374.0°C (3206.2 psia and 705.4°F).
Superheated Steam. Steam which has been heated to a
temperature above that corresponding to saturation at
a specific pressure.
Thermal Efficiency. The efficiency of the thermodynamic
cycle producing work from heat. The ration of usable
energy to heat input expressed as percent.
Thickening. Process of increasing the solids content of
siudge.
Total Dynamic Heat (TDH) . Total energy provided by a
pump consisting of the difference in elevation between
the suction and dischage levels, plus losses due to
unrecovered velocity heads and friction.
Turbidity. Presence of suspended matter such as organic
or inorganic material plantkton or other microscopic
organisms which reduce the clarity of the water.
Turbine. A device used to convert the energy of steam
or gas into rotation mechanical energy and used as prime
mover to drive electric generation.
Unit. In steam electric generation, the basic system for
power generation consiting of a boiler and its associated
turbine and generator with the required auxil'
i uuiier aria its associated
required auxiliary equipment
Utility. Public utility. A company, either investor-
owned or publicly owned which provides service to the
public in general. The electric utilities generate and
distribute electric power.
Volatile Combustion Matter. The relatively light components
in a fuel which readily vaporize at a relatively low
temperature and which when combined or reacted with
oxygen, give out light and heat.
Met Bottom Furnace. See slag-tap furnace.
Wet Bulb Temperature. The steady-state, nonequi1ibriurn
temperature reached by a small mass of water immersed under
adiabatic conditions in a continous stream of air.
XII-12
-------
DRAFT
Wet Scrubber. A device for the collection of particulate
matter from a gas stream and/or absorption of noxious
gases from the stream.
Zeolite. Complex sodium aluminum silicate materials,
which have ion exchange properties and were the
original ion exchange materials before synthetic
resins were processed.
XII-13
-------
DRAFT
APPENDIX A
STATISTICAL ANALYSIS OF HISTORICAL DATA
Effluent pretreatment standards achievable by steam electric
power plants discharging their wastewater effluents into
publicly-owned treatment facilities were determined from
statistical analysis of historical data describing the
pollutants concentration over extended periods of time. Of
the three plants analyzed only one provides partial
pretreatment which includes flow equalization, oil removal,
and settling. The remaining two plants discharge untreated
waste. This appendix describes the statistical approach
used and presents results of that analysis.
The statistical analysis was based on the assumption that
the data are normally distributed, that is, their frequency
of occurrence is fully defined by two statistical parameters:
The mean X and the standard deviation s. Each set of data
representing the variation of concentration of a particular
pollutant in treated effluent was statistically examined to
determine the mode of normal distribution that best describes
its frequency of occurrence. Both arithmetic and logarithmic
modes of normal distribution were considered. The degree of
fit of the data to any particular mode was determined by
calculating the coefficients of skewness and of kurtosis.
The former measures the symmetry of the distribution diagram
and the latter measures the height of the peak of the
diagram relative to that of a normal curve. A perfect fit
to normal distribution is indicated by a zero coefficient
of skewness and a coefficient of kurtosis of three.
If neither the arithmetic nor the logarithmic modes of
normal distribution describe the frequency of occurrence of
a data set, a modified logarithmic mode was employed to
"force" the data into normal distribution. This mode is
referred to as the three-parameters logarithmic type of
normal distribution. It is assumed that deviation from
normal distribution occurs in the tails of the frequency
curve where the probability of occurrence is very low.
Thus, it is assumed that deviation of data from the perfect
logarithmic mode of normal distribution is due to small
sample size. The overall effect of this deviation is to
increase the variance of the data set. The three-parameters
approach is designed to remove this deviation in the tails
by adding or subtracting a constant number, smaller than
the first element of the data set, to each member of the
sample. The exact value of the constant is determined by
A-l
-------
DRAFT
iterating a series of mathematical expressions designed
to generate a zero coefficient of skewness and a value
of approximately three for the coefficient of kurtosis.
The mathematical treatment of data was carried out by a
computer program. Each set of data was initially read by
the computer which sorted elements in ascending order
The computer then calculated the first four moments and
the coefficients of skewness and kurtosis for each of the
three modes of normal distribution. The statistical
coefficients of the three-parameters logarithmic mode of
normal distribution were determined by initially assigning
an arbitrary constant to be added to each element of the
data set. The computer calculated the coefficient of
skewness and determined from its value whether the
diviation from normal distribution occurred at the lower
or upper tail of the diagram. A deviation in the lower
tail was indicated by a negative value and the computer
proceeded to correct it by adding to each of the elements
naif of the arbitary constant. A positive coefficient of
skewness was corrected by subtracting half of the constant
This was_repeated until a zero coefficient of skewness
was obtained. The computer then calculated the percent
cumulative of each element in the series and converted it
to standard deviation expressed as probit (standard
deviation plus five).
Based on the values of the coefficients of skewness and
kurtosis the mode of normal distribution that best described
the distribution of the data set was selected and the data
were subjected to a least squares analysis as a function
of the corresponding probits to determine the coefficients
of regression (slope, intercept, and coefficient of
determination). The regression line was used to determine
the 99 percent confidence upper limits.
Table 1 lists the mathematical expressions used to calculate
the various statistical parameters. These are shown in
lables 2 to 6 for various pollutants discharged from three
pants. Each of these tables shows the calculated values of
the first four moments, and the coefficients of skewness and
kurtosis, for each of the modes of normal distribution Also
shown in these tables are the constants used to normalize
the distribution of the data, the coefficients of regression
(slope, intercept, and coefficient of determination), and
the 99 percent confidence limits. Plots of the best fit
data and their regression lines are shown in Figures 1 to 19
The statistical parameters of the best fit data are summarized
in Table 7. The historical data analyzed are listed in
Table 8.
A-2
-------
DRAFT
Table A-l. MATHEMATICAL EXPRESSIONS FOR DETERMINATION
OF STATISTICAL PARAMETERS _
First moment
m, = ^
(mean)
1=1
Second moment
n
1 ]T x| - X2 (variance)
1=1
Third moment
1=1
2 o _ 2 —3
xi ~ rf X /^ xi + 2X
1=1
Fourth moment
m4= n"
V
"
4 TT
rT x
6 v"2
n
Y2
1
,Tr4
1=1
Coefficient of skewness 7i = m
Coefficient of kurtosis /2 =
X
X « t -
re
dt
'V'f
P = X + 5
A-3
-------
Slope
Intercept
DRAFT
n
= x=
t *; -1 *,'
i=l ' i=l
a2 = P -
n
- E
P = 1M
Coefficient of determination
1=1
n n
V v Vp
L-i A.- X—/ r.-
1=1 ^ 1=1 ]
1=1
xi
n -
Co -
cl -
C2 -
the value of element i of a data set. X1-=X1 for arithmetic mode,
Xi=log X-j for logarithmic mode, and Xi=log (Xj + a) for three-
parameters mode of normal distribution, where a is the added or
subtracted constant.
number of elements in a data set
2.515517 d-\ - 1.432788
0.802853 d2 - 0.189269
0.010328
e(Q)< 4.5 x lO"1
0.001308
A-4
-------
Table A-2; STATISTICAL ANALYSIS OF HISTORICAL DATA (MG/L)
en
Plant No. 7308 Wastewater Source: Retention Pond
Pollutant
Mode of Normal
Distribution
Statistical
Parameter
Mean
Variance .
Third Moment
Fourth Moment
Coeff. of Skewness
Coeff. of Kurtosis
Correction Constant
Slope
Intercept
Coeff. of Determination
992 Confidence Limit
Iron
Arithmetic
4.75
0.68
0.28
0.77
0.49
1.63
1.83
-4.67
0.91
6.67
Logarithmic
4.86
0.005
0.00
0.00
0.4
1.51
Nickel
Arithmetic
2.40
51214.64^
...
—
1.45(1)
3.18(1)
Logarithmic
1.73
0.09^
0.035^
0.026^'
1.21(1)
2.87(1)
Three
Parameters
Logarithmic
1.3
0.60{1)
0.00
0.78(1)
o.oo'O)
2.H.W
-0.92
i.i50)
-4.170)
0.970)
3.1
Silver
Arithmetic
0.04
1.68'1)
-2.53*1)
6.64<]>
-1.15<1>
2.33(1)
1.58(D
-3.52(D
0.33 0)
0.07
Logarithmic
0.04
0.02{1>
-0.005^^
0.002(1)
-1.15(1)
2.33^ )
(1) calculated with data x 100
-------
Table A-3. STATISTICAL ANALYSIS OF HISTORICAL DATA (MG/L)
Plant No. 7308
Pollutant
^^ Mode of Normal
^^Distribution
S ta 1 1 s 1 1 cTl^^s^^
Parameter ^^>^^
Mean
Variance
Third Moment
Fourth Moment
Coeff. of Skewness
Coeff. of Kurtosls
Correction Constant
Slope
Intercept-
Coeff. of Determination
99X Confidence Limit
Mastewater Source: Cooling Tower Basin
Iron
Arith-
metic
5.27
10.55
12.70
255.14
0.37
2.29
4.26
-16.0
0.96
12.83
Loga-
rithmic
3.92
0.12
-0.02
0.03
-0.63
2.05
Copper
Arith-
metic
0.34
2535.43
190480.68
__.
1.49
3.23
Loga-
rithmic
0.64
0.24
0.14
0.17
1.22
2.96
Three
Para-
meters
Loga-
rithmic
0.58
0.72
0.00
1.31
0.00
2.48
-0.04
1.19
-5.21
0.87
0.8
(t) calculated with data x 100
Chromium
Arith-
metic
2.90
605. 02*1'
20240. 16(1>
1.36(1)
3.76(1)
Loga-
rithmic
2.08
0.12(1)
(i)
0.000
0.03<"
0.14W
2.23('>
Three
Para-
meters
Loga-
rithmic
2.03
0.15^
(M
0.00
0.05")
o.oo^ ')
2.29(l>
-0.14
0.507<»
-1.25<"
0.96<"
2.93
-------
Table A-3. STATISTICAL ANALYSIS OF HISTORICAL DATA (M6/L) (CONTINUED
Mocle of Normal
-^^Distribution
StatisticTT^v^^
Parameter ^^N^^^
Mean
Variance
Third Moment
Fourth Moment
Coeff. of Skewness
Coeff. of Kurtosis
Correction Constant
Slope
Intercept
Coeff. of Determination
99% Confidence Limit
Lead
Arith-
metic
0.29
543.1
11025.36
712419.5
0.87
2.41
Loga-
rithmic
0.2
0.15
-0.02
0.04
-0.29
2.02
Three
Para-
meters
Loga-
rithmic
0.33
0.08
0.00
0.01
0.00
2.00
0.05
0.37
-0.41
0.93
0.45
Zinc
Arith-
metic
3.9
359961. 0^)
_».
,.,4(2>
4.6,(2)
Loga-
rithmic
1.38
(2)
0.33
(2)
0.18
(2)
0.26
(2)
10.94
U)
2.34
Three
Para-
meters
Loga-
rithmic
0.8
iW2)
(2)
0.0
(2)
2.51
o.o 12)
2.1 f2>
-0.4
1.39(2>
W2)
0.98(2)
3.5f
pH(D
Arith-
metic
6.4
20.5(3)
(3)
-129.5
1640.0(3)
-,.3,(3)
3.8913>
Loga-
rithmic
6.3
0.001 ,
(3)
0.00
O.OC/3)
-1.5 (3)
-3.43(3>
Three
Para-
meters
Loga-
rithmic
6.4
0.0(3)
0.0^)
0.0^3)
0.0(3)
-4.03(3)
8.02
0.0l(3)
2.07(3)
0.78(3)
6.4
(1) pH units
(2) calculated with data x 100
(3) calculated with data x'10
-------
Table A-4. STATISTICAL ANALYSIS OF HISTORICAL DATA (MG/L)
oo
Want No. 8696
Pollutant
Mode of Normal
^"'-•^nfstrlbutlon
. StatlsticaT^^^
Parameter ^Vs-v^^
Mean
Variance
Third Koment
Fourth Moment
Coeff. of Skewness
Coeff. of Kurtosis
Correction Constant
Slope
Intercept
Coeff. of Determination
991 Confidence Limit
Hastewater Source: Demlnerallzer
Arith-
metic
5.5?
14.13
26.64
319.44
0.50
1.60
PHO)
Loga-
rithmic
4.161
0.10
-0.001
0.02
-0.05
1.78
Three
Para-
meters
Loga-
rithmic
4.26
0.09
0.00
0.015
0.00
1.71
0.204
0.35
-1.09
0.93
9.26
Suspended Solids
Arith-
metic
32.67
4053.73
737828.37
2.86
10.35
Loga-
rithmic
12.02
0,26
0.19
0.27
1.42
3.86
Three
Para-
meters
Loga-
rithmic
8.55
0.70
0.00
1.68
0.00
3.40
-3.54
0.96
-4.09
0.92
97.56
BODy
Arith-
metic
2.53
3.21
3.1
23.98
0.54
2.32
2.07
-7.82
0.94
6.89
Loga-
rithmic
0.2?
0.18
-0.05
0.08
-0.75
2.60
COD
Arith-
metic
28.83
424.58
12699.82
718259.0
1.45
3.98
Loga-
rithmic
23.44=
0.07
0.007
0.015
0.39
2.69
Three
Para-
meters
Loga-
rithmic
22.27
0.11
0.03
0.00
2.95
-3.65
0.38
-0.64
0.94
28.20
(1) pH units
-------
Table A-5. STATISTICAL ANALYSIS OF HISTORICAL DATA (HG/L)
Plant No. 8696 Hastewater Source: Cooling tower blowdown
Pollutant
^^ Mode of Normal
^^^^Distributlon
Statistical^\Ni_^
Parameter ^""--v^
Mean
Variance
Third Moment
Fourth Moment
foeff. of Skewness
Coeff. of Kurtosis
Correction Constant
Slope
Intercept
Coeff. of Determination
995S Confidence Limit
pH
-------
Table A-6. STATISTICAL ANALYSIS OF HISTORICAL DATA (MG/L)
Plant No. 8392 Wastewater Source: Cooling tower Boiler
Pollutant
Mode of Normal
^Distribution
Stati stical^^^
Parameter ^"""••'•^^
Mean
Variance
Third Moment
Fourth Moment
Coeff. of Skewness
Coeff. of Kurtosis
Correction Constant
Slope
Intercept
Coeff. of Determination
99% Confidence Limit
Chroma te
Arithmetic
14.94
7.31
32.69
394.28
1.65
7.37
Logarithmic
14.46
0.05
0.0002
0.0001
0.66
5.63
Three
Parameters
Logarithmic
14.53
0.01
0.00
0.001
0.00
5.37
-5.62
0.12
0.34
0.77
16.24
Phosphate
Arithmetic
17.1
13.98
10.86
569.44
0.20
2.90
Logarithmic
16.59
0.009
-0.0003
0.0002
-0.36
2.82
Three
Parameters
Logarithmic
16.51
0.002
0.00
0.00
0.00
-3.10
19.99
0.05
1.31
0.97
17.18
-------
Table A-7. STATISTICAL PARAMETERS SUMMARY FOR BEST FIT DATA (MG/L)
Cooling Tower Slowdown
Source (Plant 8696)
Parameter
PH
Suspended Solids
BODS
COO
Source
Parameter
Chromate
Phosphate
Statistical
Mode
Arithmetic
3-Parameter
Logarithmic
3-Parameter
Concentration
Mean
7.46
13.59
2.36
26.40
991
Confidence
Limit
8.11
15.39
3.85
27.55
Cooling Tower Slowdown
(Plant 8392)
3-parameter
14.53
16.24
Source Cooling Tower Basin
(Plant 7308)
Parameter
Fe
Cu
Cr
Pb
Zn
pH
Statistical
Mode
Arithmetic
3-parameter
3-parameter
3-parameter
3-parameter
3-parameter
Concentration
Mean
5.27
0.58
2.03
0.33
0.8
6.4
991
Confidence
Limit
12.83
0.60
2.93
0.45
3.23
6.4
Source Retention Pond
Parameter
Fe
N1
Ag
Art thmctlc
3-parameter
Arithmetic
4.75
1.3
.0.04
6.67
3.1
0.03
Demlnerallzer
(Plant 8696)
Statistical
Mode
3-parameter
3-parameter
Arithmetic
3-paraneter
Concentration
Mean
4.26
8.55
2.53
22.27
991
Concentration
Limit
9.26
97.56
6.89
28.20
Boiler
(Plant 8392)
3-parameter
16.51
17.78
o
73
-------
DRAFT
Table A-8. HISTORICAL DATA_(MG/L_
Plant Ho. 8696
Cooling Tower Slowdown
PH
7.98, 7.35
7.27, 7.94, 7.08, 7.4, 7.26, 7.72, 7.14, 7.5, 7
7.72, 7.4, 7.97, 7.14, 7.25, 7.35, 7.23, 7.65,
.33,
7.39,
SS 11.0, 23.0, 23.0, 14.0, 15.6,
16.0, 19.6, 13.5, 17.6, 11.0,
BOD, 2.7, 3.0, 1.0, 2.1, 3.7, 3.7,
5 3.2,2.5,2.2,1.9,1.6,1.3,
COD 24.0, 29.0, 27.0, 12.0, 33.0,
2.2, 24.0, 23.0, 21.0, 20.0
Demineralizer Backwash
12.0,
12.0,
7.2, 13, 11
8.4
3.3, 3.8, 3.9, 2.S
1.4, 1.6
30.0, 30.0, 31.0,
pH
SS
BOD5
COD
Plant No.
1.0,
2.72
96.0
10.8
4.7,
3.0,
22.0
39.0
18.0
8392
5.77
, 10.
, 8.4
, 3.6
0.3,
2.8,
, 19-
, 39.
, 11.
10
-
0
3
0,
0,
0
1 .95
, 9.
11 .0
8.6,
.2,
.3,
21 ,
13.
, 3.23, 2.86, 3.26, 9.52, 2.16,
87, 11 .65, 9.8, 1 .72, 12.0, 2.7
, 9.6, 5.6, 6.4, 4.0, 5.2, 19.0
84.0, 8.0, 264.0, 6.4, 4.8
0.7, 0.9, 1.0, 2.7, 5.8, 6.2, 3
2.1, 3.8, 1.6, 0.8;
0, 7.0, 13.0, 22.0, 22.0, 24. 0-,
0, 71.0, 57.0, 18.0, 20.0, 83.0
6.42,
, 2.78
•
-2,
'
Cool i nq Tower
Chromate
Boiler
Phosphate
Plant No.
Retention
Fe
Ni
Ag
16,0
12.0
14.0
15.0
17.0
7308
Pond
4.0,
1.35
0.05
, 24,
, 10.
, 18.
, 14.
0,
0,
0,
0,
179.0,
, 6.9
,
, 0.05,
18.
14.
16.
12.
4.0
1.1,
0, 14.0, 16.0, 14.0, 14.0, 14.0
0, 14.0, 16.0, 14.0, 14.0, 16.0
0, 26.0, 19.0, 15.0, 18.0, 13.0
0, 10.0, 20.0, 13.0, 21 .0, 19.0
, 6.0, 5.0
1 .72, 0.95
, 14.0
, 16.0
, 20.0
, 18.0
0.05, 0.02
Cooling Tower Basin
Fe 11.4, 7.25, 5.75, 1.0, 7.5, 3.5, 4.5, 1.3
Cu 0.05, 1 .35, 0.12, 0.1 , 0.1
Cr 2.0, 4.0, 4.0, 8.6, 1.1, 0.55, 1.5, 1.5
Pb 0.25, 0.75, 0.05, 0.6, 0.25, 0.25, 0.18, O.Ob
Zn 7.85, 18.75, 0.8, 0.7, 0.45, 1.75, 0.54, 0.41
A-12
-------
DRAFT
500
100
50
en
E
10
Q
•o
0)
N
E
i-
O
10
3.0
4.0
5.0
PROBITS
6.0
7.0
FIGURE A-l. Normal Distribution Diagram for Supsended Solids
Concentration in Wastewaters from Demineralizer
(Plant 8696)
A-13
-------
100
10
•u
o>
s_
o
50
10
3.0
4.0
1
5.0
PROBITS
6.0
o
73
7.0
FIGURE A-2, Normal Distribution Diagram for Phosphates Concentration
In Boiler Slowdown (Plant 8696)
-------
CO
X.
QJ
ts!
"3
E
t.
o
4.0
5.0
PROBITS
6.0
7.0
FIGURE A-3, Normal Distribution Diagram for pH Concentration
In Wastewater from Deminealizer (Plant 8696)
-------
DRAFT
100
50
o>
Q
OJ
•r—
-------
I
»-J
50
id
to
O
to
e-
S-
o
10
3.0
4.0
5.0
PROBITS
o
70
6.0
7.0
FIGURE A-5. Normal Distribution Diagram for Supsended Solids Concentration
In Cooling Tower Slowdown (Plant 8696)
-------
i
..j
00
D)
E
(O
4_>
to
X)
Ol
fsl
(O
E
£-
O
3.0
4.0
O O
5.0
PROBITS
o
73
6.0
7.0
FIGURE A-e. Normal Distribution Diagram for COD Concentration In
Cooling Tower Slowdown (Plant 8696)
-------
50
10
to
Q
0)
N
(O
E
1-
O
o
PO
3*
3.0
4.0
5.0
PROBITS
6.0
7.0
FIGURE A-7. Normal Distribution Diagram for Chromates Concentration In
Cooling Tower Slowdown (Plant 8395)
-------
to
4J
-------
ro
Z- 9.0
c
to
1o 8.0
S_
o
7.0
6.0
3.0
4.0
5.0
PROBITS
6.0
7.0
FIGURE A-9.. Normal Distribution Diagram for pH Concentration In
Cooling Tower Slowdown (Plant 8696)
-------
DRAFT
to
4J
ia
o
•a
-------
DRAFT
10'
~ 10'
(0
ro
•o
01
N
s-
o
10
3.0
4.0
5.0
PROBITS
6.7
7.0
FIGURE A-11-. Normal Distribution Diagram for Normalized Nickel
Concentration in Retention Pond (Plant No. 7308)
A-23
-------
DRAFT
10"
O)
£
03
Q
-a
-------
DRAFT
10"
03
•M
fO
Q
•o
-------
DRAFT
1C
o>
to
4J
TD
0)
N
to
E
10
10
3.0
4.0
5.0
PROBITS
6.0
7.0
FIGURE A-14. Normal Distribution Diagram for Normalized
Zinc Concentration In Cooling Tower Basin (Plant No. 7308)
A-26
-------
DRAFT
8.0
7.0
01
e
(O
6.0
•o
OJ
5.0
(O
£
4.0
3.0
4.0
5.0
PROBITS
6.0
7.0
FIGURE A-15. Normal Distribution Diagram for Iron
Concentration in Retention Pond (Plant No. 7308)
A-27
-------
ro
CO
12.0
10.0
a-.
"O
O)
N
S_
O
2.0
3.0
7.0
FIGURE A-16. Normal Distribution Diagram for Iron Concentration
In Cooling Tower Basin (Plant No. 7308)
-------
200
o
o
150
I
ro
10
-------
DRAFT
8.0
6.0
-------
DRAFT
10'
en
e
(O
•M
ttl
O
•o
O)
10
S-
o
10'
10
3.0
4.0
5.0
PROBITS
6.0
7.0
FIGURE A-19. Normal Distribution Diagram for Normalized
copper Concentration Cooling Tower Basin (Plant No.7308)
A-31
-------
DRAFT
APPENDIX B
WATER GLOSSARY
B-l
-------
DRAFT
WATER GLOSSARY
Acid-washed activated carbon - Carbon which has been con-
tacted with an acid solution with the purpose of
dissolving ash in the activated carbon.
Acidity - The quantitative capacity of aqueous solutions
to react with hydroxyl ions. It is measured by
titration with a standard solution of a base to a
specified end point. Usually expressed as miligrams
per liter of calcium carbonate.
Acre-foot - (1) A term used in measuring the volume of
water that is equal to the quantity.of water required
to cover 1 acre 1 ft deep, or 43,560 cu ft. (2) A
term used in sewage treatment in measuring the volume
of material in a trickling filter. One acre-foot
contains 43,560 cu ft of water.
Activated Carbon - Carbon which is treated by high-tempera-
ture heating with steam or carbon dioxide producing
an internal porous particle structure. The inter-
nal surface area of granular activated carbon is
estimated to be about 3,600 sq ft gr.
Activiated Sludge Treatment Process - (See Sludge, Activated)
Adsorption - The adhesion of an extremely thin layer of
molecules (of gas, liquid) to the surfaces of solids
(granular activiated carbons for instance) or liquids
with which they are in contact.
Adsorption isotherms (activated carbon) - A measurement of
adsorption determined at a constant temperature by
varying the amount of carbon used or the concentration
impurity in contact with the carbon.
Advanced Waste Treatment - Any treatment method or process
employed following biological treatment (1) to increase
the removal of pollution load. (2) to remove substances
that may be deleterious to receiving waters or the
environment. (3) to produce a high-quality effluent
suitable for reuse in any specific manner or for dis-
charge under critical conditions. The term tertiary
treatment is commonly used to denote advanced waste
treatment methods.
B-2
-------
DRAFT
Aerated Pond - A natural or artificial wastewater treatment
pond in which mechanical or diffused air aeration is
used to supplement the oxygen supply.
Aeration - The bringing about of intimate contact between
air and liquid by one of the following methods spraying
the liquid in the air, bubbling air through the liquid
(diffused aeration) agitation of the liquid to promote
surface absorption of air (mechanical aeration).
Aerobic - Living or active only in the presence of oxygen.
Aerobic Biological Oxidation - Any waste treatment or pro-
cess utilizing aerobic organisms in the presence of
air or oxygen, as the agent for reducing pollution load
or oxygen demand or organic substances in waste. The
term is used in reference to secondary treatment of
wastes.
A1 gicide - Chemicals used in the control of phytoplankton
(algae) in bodies of water.
Alkalinity - The capacity of water to neutralize acids, a
property imparted by the water's content of carbonates,
bicarbonates, hydroxides, and occassionally borates,
silicates, and phosphates. It is expressed in mill-
grams per liter of equivalent calcium carbonate.
Anaerobic - Living or active only in the absence of free
oxygen.
Anaerobic Biological Treatment - Any treatment method or
process utilizing anaerobic or facultative organisms
in the absence of air for the purpose of reducing
the organic matter in wastes or organic solids settled
out of wastes commonly referred to as anaerobic diges-
tion or sludge digestion when applied to the treatment
of siudge sol ids .
Anaerobic Waste Treatment - Waste stabilization brought about
through the action of microorganisms in the absence
of air or elemental oxygen. Usually refers to waste
treatment by methane fermentation.
B-3
-------
DRAFT
Anion Exchange Process - The reversible exchange of nega-
tive ions between functional groups of the ion exchange
medium and the solution in which the solid is immersed.
Used as a wastewater treatment process for removal of
anions, e.g., carbonate.
Anionic Surfactant - An ionic type of surface-active sub-
stances that has been widely used in cleaning products.
The hydrophilic group of these surfactants carries a
negative charge in washing solution.
Apparent Density (Activated Carbon) - The weight per unit
volume of activated carbon.
Appurtenances, Sewer - Structures, devices and appliances,
other than pipe or conduit, which are integral parts
of a sewerage system: such as manholes flush tanks,
surface inlets.
Aquifer - A subsurface geological structure that contains
water.
Assimilative Capacity - The capacity of a natural body of
water to receive: (a) wastewaters without deleterious
effects: (b) toxic materials, without damage to
aquatic life or humans who consume the water; (c) BOD
within prescribed dissolved oxygen limits.
Autooxidation - A chemical system which will oxidize auto-
matically when some set of conditions are met such as
temperature, oxygen supply, moisture content, etc.
Backflow Prevention - A system designed to protect potable
water from wastewater contamination which could occur
if wastewater pressure exceeds potable water pressure
over a cross-connection where one or more check valves
fail .
Backsiphonage - The flowing back of contaminated or polluted
water from a plumbing fixture or cross connection into
a water supply line, due to a lowering of the pressure
in such line.
Backwashing - The process of cleaning a rapid sand or mech-
anical filter by reversing the flow of water.
B-4
-------
DRAFT
Bacterial Examination - The examination of water and waste-
water to determine the presence, number, and identifi-
cation of bacteria. Also called bacterial analysis.
Baffles - Deflector vanes, guides, grids, gratings, or
similar devices constructed or placed in flowing water
or sewage to (1) check or effect a more uniform dis-
tribution of velocities; (2) absorb energy; (3) divert
guide, or agitate the liquids; and (4) check eddy
currents.
Banks. Sludge - Accumulations on the bed of a waterway of
deposits of solids of sewage or industrial waste
origin.
Bed Depth (Activated Carbon) - The amount of carbon expressed
in length units which is parallel to the flow of the
stream and through which the stream must pass.
Bioassay - (1) An assay method using a change in biological
activity as a qualitative or quantitative means of
analyzing a materials reponse to industrial wastes and
other wastewaters by using viable organisms or live
fish as test organisms.
Biochemical Oxygen Demand (BOD) - (1) The quantity of oxygen
used in the biochemical oxidation of organic matter in
a specified time, at a specified temperature, and under
specified conditions (2) standard test used in assess-
ing wastewater strength.
B i o c i d e s - Chemical agents with the capacity to kill bio-
logical life forms. Bactericides, insecticides, pesti-
cides, etc. are examples.
Bi odegradable - This part of organic matter which can be
oxidized by bioprocesses, e.g., biodegradable deter-
gents, food wastes, animal manure, etc.
Biological Wastewater Treatment - Forms of wastewater treat-
ment in which bacterial or biochemical action is inten-
sified to stablize, oxidize, and nitrify the unstable
organic matter present. Intermittent sand filters, con-
tact beds, trickling filters, and activated sludge
process are examples.
B-5
-------
DRAFT
Blowoff - A controlled outlet on a pipeline, tank, or
conduit which is used to discharge water or accumu-
lations of material carried by the water.
Branch - (1) A special form of vitrified sewer tile and
cast iron pipe used for making connections to a sewer
or water main. They are called T, Y, T-Y, double Y,
and V branches according to their respective shapes.
(2) Any part of a piping system other than a main.
Broad-Crested Weir - A weir having a substantial width of
crest in the direction parallel to the direction of
flow of water over it. This type of weir supports
the nappe for an appreciable length and produces no
bottom contraction of the nappe. Also called wide-
crested weir.
Buffer - Any of certain combinations of chemicals used to
stablize the pH values or alkalinities of solutions.
Bui king Agent - A fine solid material which is sometimes
added to a wastewater stream to promote clarification
or coagulation by adding bulk to the solids.
Bulking, Sludge - A phenomenon that occurs in activated
sludge plants whereby the sludge occupies excessive
volumes and will not concentrate readily.
Cake, Sludge - The material resulting from air drying or
dewatering sludge (usually forkable or spadable).
Cali brat ion - The determination, checking, or rectifying
of the graduation of any instrument giving quantitative
measurements.
Carbon Column A - A column filled with granular activated
carbon whose primary function is the preferential ad-
sorption of a particular type or types of molecules.
Carbon Tetrachloride Activity - The maximum percentage
increase in weight of a bed of activated carbon after
air saturated with carbon tetrachloride is passed
through it at a given temperature.
Catalyst - A substance which accelerates or retards a
chemical reaction without undergoing any permanent
changes .
B-6
-------
DRAFT
Cation Exchange Process - The reversible exchange of positive
ions between functional groups of the ion exchange medium
and the solution in which the solid is immersed. Used
as a wastewater treatment process for removal of cations,
e.g. calcium.
Cationic Surfactant - A surfactant in which the hydrophilic
group is positively charged; usually a quaternary
ammonium salt such as cetyl trimethyl ammonium bro-
mide (CeTAB), C16H33N + (CHs)3 Br Cationic surfactant
as a class are poor cleaners, but exhibit remarkable
disinfectant properties.
Cesspool - An underground pit into which raw household sewage
or other untreated liquid waste is discharged and from
which the liquid seeps into the surrounding soil or is
otherwise removed. Sometimes called leaching cesspool.
Chamber Detritus - A detention chamber larger than a grit
chamber usually with provision for moving sediment
without interrupting the flow of liquid. A settling
tank of short detention period designed, primarily
to remove heavy settleable solids.
Chamber, Flowing-Through - The upper compartment of a two-
story sedimentation tank.
Chamber, Grit - A small detention chamber or an enlargement
of a sewer designed to reduce the velocity of flow of
the liquid, to permit the separation of mineral from
organic solids by differential sedimentation.
Chelating Agents - A chelating agent can attach itself to
central metallic atom so as to form a heterocyclic
ring. Used to make ion-exchange more selective for
specific metal ions such as nickel, copper, and cobalt.
Chemical Analysis - The use of a standard chemical analyti-
cal procedures to determine the concentration of a
specific pollutant in a wastewater sample.
Chemical Coagulation - The destabi 1 ization and initial
aggregation of colloidal and finely divided suspended
matter by the addition of a floe-forming chemical.
B-7
-------
DRAFT
Chemical Oxygen Demand (COD) - (1) A test based on the fact
that all organic compounds, with few exceptions can be
oxidized to carbon dioxide and water by the action of
strong oxidizing agents under acid conditions. Organic
matter is converted to carbon dioxide and water regard-
less of the biological assimi1abi1ity of the substances,
One of the chief limitations is its ability to dif-
ferentiate between biologically oxidizable and biolo-
gically inert organic matter. The major advantage of
this test is the short time required for evaluation
(2 hr). (2) The amount of oxygen required for the
chemical oxidation of organics in a liquid.
Chemical Precipitation - (1) Precipitation induced by addi-
tion of chemicals, (2) the process of softening water
by the addition of lime and soda ash as the precipi-
tants .
Chemi sorption - Adsorption where the forces holding the
adsorbate to the adsorbent are chemical (valance)
instead of physical (van der Waals).
Chlorination - The application of chlorine to water or waste-
water, generally for the purpose of disinfection, but
frequently for accomplishing other biological or
chemical results.
Chlorination break point - The application of chlorine to
water, sewage, or industrial waste containing free
ammonia to the point where free residual chlorine is
available.
Chlorination, Free Residual - The application of chlorine
to water, sewage or industrial wastes to produce
directly or through the destruction of ammonia, or of
certain organic nitrogenous compounds a free available
chlorine residual.
Chlorine, Available - A term used in rating chlorinated
lime and hypochlorites as to their total oxidizing
power. Also a term formerly applied to residual
chlorine; now obsolete.
Chlorine, Combined Available Residual - That portion of the
total residual chlorine remaining in water, sewage or
industrial wastes at the end of specified contact
period, which will react chemically and biologically as
chloramines or organic chloramines.
B-8
-------
DRAFT
Chlorine Demand - The quantity of chlorine absorbed by
wastewater (or water) in a given length of time.
Chlorine, Total Residual - Free residual plus combined
residual.
Chlorite, High-test Hypo - A combination of lime and
chlorine consisting largely of calcium hypochloride.
Chlorite, Sodium Hypo - A water solution of sodium hydroxide
and chlorine, in which sodium hypochlorite is the
essential ingredient.
Cipolletti Weir - A contract weir of trapezoidal shape, in
which the sides of the notch are given a slope of one
horizontal to four vertical to compensate as much as
possible for the effect of end contractions.
Clari fi er - A sedimentation tank.
Clear Wei 1 - A reservoir containing water which has been
previously filtered or purified before goining into
the standpipes or distribution system.
Coils, digester - A system of pipes for hot water or steam
installed in a sludge digestion tank for the purpose
of heating the sludge being treated.
Collection Systems - Piping and/or channel systems for
gathering storm, domestic or industrial wastewaters.
Can be combined or separate.
Collector, Grit - A device placed in a grit chamber to
convey deposited grit to one end of the chamber for
removal.
Collector, Sludge - A mechanical device for scraping the
sludge on the bottom of a settling tank to a sump
pump, from which it can be drawn by hydrostatic or
mechanical action.
Colloids - A finely divided dispersion of one material
called the "dispersed phase" (solid) in another
material which is called the "dispersion medium"
(liquid). Normally negatively charged.
B-9
-------
DRAFT
Color - A measure of water quality, made by eye or with
proper instrumentation.
Color Bodies - Those complex molecules which impart color
(usually undesirable) to a solution.
Comminution - The process of cutting and screening solids
contained in wastewater flow before it enters the flow
pumps or other units in the treatment plant.
Compatable Pollutant - A specific substance in a waste
stream which alone can create a potential pollution
problem, yet is used to the advantage of a certain
treatment process when combined with other waste
streams.
Complexing - The use of chelating or sequestering agents
to form relatively loose chemical bonding as a means
of treating certain pollutant such as nickel, copper,
and cobalt.
Composite Wastewater Sample - A combination of individual
samples of water or wastewater taken at selected
intervals, generally hourly for some specified period,
to minimize the effect of the variability of the
individual sample. Individual samples may have equal
volume or may be roughly proportioned to the flow at
time of sampling.
Concentration, Hydrogen Ion - The weight of hydrogen ions
in grams per liter of solution. Commonly expressed as
the pH value that represents the logarithms of the
receiprocal of the hydrogen ion concentration.
Conductance - A measure of the conducting power of a solution
equal to the reciprical of the resistance. The re-
sistance is expressed in ohms.
Contact Coagulation - A water clarification process which
involves the addition of a coagulant with appropriate
mixing for the purpose of floe formation within a
filter media, which will be periodically back-flushed
to permit the separation of the resulting solids from
the main wastewater stream.
B-10
-------
DRAFT
Contamination - A general term signifying the introduction
into water of microorganisms, chemicals, wastes or
sewage which renders the water unfit for its intended
use.
Contracted Weir - A V-notch or other shaped cross-section
weir for the purpose of flow measurement, as opposed
to a broad width weir for the purpose of level control.
Contraction - (1) The extent to which the cross-sectional
area of a jet, nappe, or stream is decreased after
passing an orifice, weir, or notch. (2) The reduction
in cross-sectional area of a conduit along its long-
itudinal axis.
Control Section - The cross-section in a waterway which is
the bottleneck for a given flow and which determines
the energy head required to produce the flow.
Corporation Cock -A valve for joining a service pipe to a
street water main; it is generally owned and operated
by the water utility or department. It cannot be
operated from the surface.
Countercurrent Efficiency (Activated Carbon) - The unique
advantage of a carbon column that permits spent anti-
vated carbon to adsorb impurities before the semi-
processed stream comes in contact with fresh carbon.
This allows the maximum capacity of the activated
carbon to be utilized.
Crest - The top of a dam, spillway, or weir, to which
water must rise before passing over the structure.
Critical Bed Depth (Activated Carbon) - In a carbon column
the critical bed depth is the depth of granular
carbon which is partially spent. It lies between the
fresh carbon and the spent carbon and is the zone
where adsorption takes place. In a single-column
system this is the amount of carbon that is not com-
pletely utilized.
Cross Connection - A water supply network and/or wastewater
collection system which as been designed so as to pre-
vent "cross-connections" which could result in func-
tional damage to the system. The simpliest system is
to have two separate systems, but this would not be
justified if intersystems usage occurs only occasionally,
hence back-flow preventers and other means are often
used.
B-ll
-------
DRAFT
Cross-Sectional Bed Area (Activated Carbon) - The area of
activated carbon through which the stream flow is
perpendicular.
Curb Cock - A shutoff valve attached to the water service
pipe from the water basin to the building installed
near the curb, which may be operated by means of a
dye key to start or stop flow in the water supply
lines of a building.
Current Meter - A device for determining the velocity of
moving water.
Curve, Oxygen, Sag - A curve that represents the profile
of dissolved oxygen connect along the course of a
stream, resulting from deoxygenation associated with
biochemical oxidation of organic matter and re-
oxygenation through the absorption of atmospheric
oxygen and through biological photosynthesis.
Data - Records of observations and measurements of physical
facts, occurrences, and conditions, reduced to written,
graphical, or tabular form.
Data Correlation - The process of the conversion of reduced
data into a functional relationship and the develop-
ment of the significance of both the data and the
relationships for the purpose of process evaluation.
Data Reduction - The process for the conversion of raw
field data into a systematic flow which assists in
recognizing errors, omissions and the overall data
quality.
Data Significance - The result of the statistical analysis
of a data group or bank wherein the value or signi-
ficance of the data receives a thorough appraisal.
Dechlorination Process - A process by which excess chlorine
is removed from water to a desired level, eg. 0.1
mg/1 maximum limit. Usually accomplished by chemical
reduction, by passage through carbons beds or by
aeration at a suitable pH.
Degreasing - The process of removing greases and oils from
sewage, waste, and sludge.
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Demand. Biochemical Oxygen (BOD) - The quantity of oxygen
utilized in the biochemical oxidation of organic
matter in a specified time period and at a specified
temperature. It is not related to the oxygen require-
ments in chemical combustion being determined entirely
by the availability of the material as a biological
food and the amount of oxygen by the microorganisms
during the oxidation.
Desorption - The opposite of adsorption. A phenomenon
where an adsorbed molecule leaves the surface of the
adsorbent.
Detention Time - The time allowed for solids to collect in
a settling tank. Theoretically detention time is equal
to the volume of the tank divided by the flow rate.
The actual detention time is determined by the purpose
of the tank. Also, the design resident time in a
tank or reaction vessel which allows a chemical re-
action to go to completion, such as the reduction of
chromium +6 or the destruction of cyanide.
Dialysis - The separation of a colloid from a substance in
true solution by allowing the solution to diffuse
through a semi-permeable membrane.
Diatomaceous Earth - A.filter medium used for filtration
of effluents from secondary and tertiary treatments,
particularly when a very high grade of water for
reuse in certain industrial purposes is required
also used as an adsorbent for oils and oily emulsions
in some wastewater treatment designs.
Differential Gauge - A pressure gauge used to measure the
difference in pressure between two points in a pipe
or receptacle containing a liquid.
Pi ffuser - A porous plate or tube through which air is
forced and divided into minute bubbles for diffusion
in liquids. Commonly made of carborundum, alundum
and silica sand.
Diffusion. Ridge and Furrow Air - A method of diffusing in
an aeration tank of the activated sludge process, where
porous tile diffusers are placed in depressions treated
by the sawtooth construction of the tank bottom, in
rows across the tank at right angles to the direction
of flow.
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DRAFT
Diffusion, Spiral Flow Air - A method of diffusing air in a
aeration tank of the activated sludge process, where
by means of properly designed baffles and the proper
location of diffusers, a spiral helieal movement is
given to both the air and the liquor in the tank.
Digestion - The biochemical decomposition of organic matter
which results in the formation of mineral and simpler
organic compounds.
Pi sinfection - (1) The killing of the larger portion (but
not necessarily all) of harmful and objectionable
microorganisms in or on a medium by means of
chemicals, heat, ultraviolet light, etc. (2) The use
of a chemical additive or other treatment to reduce
the number of bacteria particularly the pathogenic
organisms.
Dissolved Oxygen (DO) - The oxygen dissolved in sewage,
water, or other liquid, usually expressed in miligrams
per liter or percent of saturation. It is the test
used in BOD determination.
Dissolved Solids - Theoretically the anhydrous residues of
the dissolved constituents in water. Actually the
term is defined by the method used in determination.
In water and wastewater treatment the Standard Methods
tests are used.
Diurnal Flow Curve - A curve which depicts flow distribution
over the 24 hour day.
Drinking Water Standards - Standards defined by law and
applied to the quality of drinking water.
Educator (Activated Carbon) - A device with no moving parts
used to force an activated carbon water slurry
through pipes to the desired location.
Eff1uent - (1) A liquid which flows out of a containing
space (2) sewage, water or other liquid, partially
or case may be, flowing out of a reservoir basin, or
the use may be flowing out of a reservoir basin, or
treatment plant or part thereof.
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DRAFT
Electrical Conductivity - The reciprocal of the resistance
in ohms measured between opposite faces of centimeter
cube of an aqueous solution at a specified temperature.
It is expressed as microohms per centimer at tempera-
ture degrees Celsius.
Elutriation - A process of sludge conditioning in which
certain constituents are moved by successive flushing
with fresh water or plant effluent thereby reducing
the need for using conditioning chemicals.
Emergency Procedures - These various special procedures
necessary to protect the environment from wastewater
treatment plant failures due to power outages, chemi-
cal spills, equipment failures, major storms and floods
etc.
Emulsion Breaking - The method of preventing the carryover
of oils from one process to another by eliminating free
oil by flotation, and emulsions by the addition of
aluminum or ferrous sulfate.
End Contraction - (1) The extent of the reduction in the
width of the nappe due to a constriction caused by
the ends of the weir notch. (2) The walls of a weir
notch which does not extend across the entire width
of the channel of approach.
Energy Head - The height of the hydraulic grade line above
the center line of a conduit plus the velocity head of
the mean velocity of the water in that section.
Equalization Tank - A capacity used to equalize wastewater
flows or pollutant concentrations in effluents thus
distributing it more evenly by hours or days.
Euetrophic Conditions - Lake water quality degradation by
enrichment of nutrients resulting in characteristics
undersirable for means use of water. Plant growth
in forms of microscopic algae and rooted aquatic
weeds become prevalent in such situations.
Fats (Wastes) - Triglyceride esters of fatty acids.
Erroneously used as synonomous with grease.
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Faculative - Having the power to live under different
conditions either with or without oxygen.
Feeder, Chemical, Dry- A mechanical device for applying
dry chemicals to water sewage at a rate controlled
manually or automatically by the rate of flow.
Feeder Chemical Solution - A mechanical device for apply-
ing chemicals in liquid to water and sewage at a
rate controlled manually or automatically by the
rate of flow.
Filter, High-Rate - A trickling filter operated at a high
average daily dosing rate. All between 10 and 30
mgd acre, sometimes including recirculation of
effluent.
Filter, Intermittent - A natural or artifical bed of sand
or other fine-grained material to the surface of
which sewage is intermittently added in flooding
doses and through which it passes, opportunity being
given for filtration and the maintenance of aerotic
conditi ons .
Filter, Low-Rate - A trickling filter designed to receive
a small load of BOD per unit volume of filtering
material and to have a low dosage rate per unit of
surface area (usually 1 to 4 mgd/acre). Also called
standard rate filter.
Filter, Rapid Sand - A filter for the purification of water
where water which has been previously treated, usually
by coagulation and sedimentation is passed downward
through a filtering medium consisting of a layer of
sand or prepared anthracite coal or other suitable
material, usually from 24 to 30 in thick and resting
on a supporting bed of gravel or a porous medium such
as carborundum. The filrate is removed by an under-
drain system. The filter is cleaned periodically by
reversing the flow of the water upward through the
filtering medium: sometimes supplemented by mechanical
or air agitition during backwashing to remove mud and
other impurities that are lodged in the sand.
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DRAFT
Filter, Roughing - A sewage filter of relatively coarse
material operated at a high rate as a preliminary
treatment.
Filter, Trickling - A filter consisting of an artifical bed
of coarse material, such as broken stone, clinkers,
slats, or brush over which sewage is distributed and
applied in drops, films, or spray, from troughs,
drippers moving distributors or fixed nozzles and
through which it trickles to the underdrain giving
opportunity for the formation of zoogleal slimes
which clarify and oxidize the sewage.
Filter, Vacuum - A filter consisting of a cylindrical drum
mounted on a horizontal axis, covered with a filter
cloth revolving witha partial sumergence in liquid.
A vacuum is maintained' under the cloth for the larger
part of a revolution to extract moisture and the
cake is scraped off continously.
Filtration, Biological - The process of passing a liquid
through a biological filter containing media on the
surfaces of which zoogleal films develop which absorb
and adsorb fine suspended colloridal and dissolved
solids and which release various biochemical end
products.
Float Gauge - A device for measuring the elevation of the
surface of a liquid, the actuating element of which
is"a buoyant float that rests on the surface of the
liquid and rises or falls with it. The elevation of
the surface is measured by a chain or tape attached
to the float.
Floc - A very fine, fluffy mass formed by the aggregation
of fine suspended particles.
Flocculator - An apparatus designed for the formation of
floe in water or sewage.
Flpeculation - In water and wastewater treatment, the
agglomeration of colloidal and finely divided sus-
pended matter after coagulation by gentle stirring
by either mechanical or hydraulic means. In bio-
logical wastewater treatment where coagulation is not
used, agglomeration may be accomplished biologically.
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Floatation - The rising of suspended matter to the surface
of the liquid in a tank as scum by aeration, the
evolution of gas, chemicals, electrolysis, heat, or
bacterial decomposition and the subsequent removal
of the scum by skimming.
Flowrate - Usually expressed as liters/minute (gallons/
minute) or liters/day (million gallons/day). Design
flowrate is that used to size the wastewater treatment
process. Peak flowrate is 1.5 to 2.5 times design
and relates to the hydraulic flow limit and is
specified for each plant. Flowrates can be mixed
as batch and continuous where these two treatment
modes are used on the same plant.
Flow-Nozzle Meter - A water meter of the differential
medium type in which the flow through the primary
element or nozzle produces a pressure difference or
differential head, which the secondary element, or
float tube then uses as an indication of the rate of
f 1 ow.
Flow-Proportioned Sample - A sampled stream whose pollutants
are attributed to contributing streams in proportion
to the flow rates of the contributing streams.
Frequency Distribution - An arrangement or distribution of
quantities pertaining to a single element in order
of thei r magni tude.
Gauging Station - A location on a stream or conduit where
measurements of discharge are customarily made. The
location includes a stretch of channel through which
the flow is uniform and a control downstream from
this stretch. The station usually has a recording
or other gauge for measuring the elevation of the
water surface in the channel or conduit.
Grab Sample - A single sample of wastewater taken at
neither set time nor flow.
Grease - In wastewater, a group of substances including fats,
waxes, free fatty acids, calcium and magnesium soaps,
mineral oils, and certain other nonfatty materials.
The type of solvent and method used for extraction
should be stated for quantification.
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Grease Skimmer - A device for removing floating grease or
scum from the surface of wastewater in a tank.
Grit - The heavy matter in water or sewage such as sand,
gravel and cinders.
Grit Chamber - A detention chamber or an enlargement of a
sewer designed to reduce the velocity of flow of the
liquid to permit the separation of mineral from
organic solids by differential sedimentation.
Hardness - A characteristic of water, imparted by salts of
calcium, magnesium, and iron such as bicarbonates,
carbonates, sulfates, chlorides, and nitrates that
cause curdling of soap, deposition of scale in boilers,
damage in some industrial process, and sometimes
objectionable taste. It may be determined by a stand-
ard laboratory procedure or computed from the amounts
of calcium and magnesium as well as iron, aluminum,
manganese, barium, strontium, and zinc, and is
expressed as equivalent calcium carbonate.
Heat of Adsorption - The heat given off when molecules are
adsorbed.
Heavy Metals - A general name given to the ions of metallic
elements such as copper, zinc, chromium, and aluminum.
They are normally removed from a wastewater forming an
insoluble precipitate (usually a metallic hydroxide).
Hook Gauge - A pointed, U-shaped hook attached to a gradu-
ated staff or vernier scale, used in the accurate
measurement of the elevation of a water surface. The
hook is submerged, and then raised, usually by means
of a screw, until the point just makes a pimple on
the water surface.
Hydraulic Surge - A pressure increase in a pipeline which
accompanies a sudden decrease in the flow velocity.
In some cases this increased pressure may cause
rupture of the pipe.
Industrial Wastes - The liquid wastes from industrial pro-
cesses as distinct from domestic or sanitary wastes.
Incineration - The combustion (by burning) of organic matter
in wastewater sludge solids after water evaporation
from the solids.
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DRAFT
Index, Sludge - The volume of mi 11 i 11 ters occupied by aerate'd
mixed liquor containing 1 gram of dry solids after
settling 80 min. commonly referred to as the Mohlman
index. The Donaldson index which is also commonly
used is obtained by dividing 100 by the Mohlman index.
Influent - Sewage, water or other liquid, either raw or
partly treated, flowing into a reservoir basin, or
treatment plant or any part thereof.
Invert - The floor, bottom or lowest portion of the internal
cross section of a closed conduit.
Iodine Number (Activated Carbon) - The iodine number is the
mflliliterof iodine adsorbed 1 gram of carbon at a
filtrate concentration of 0.02N iodine.
Ionization - The process of the formation of ions by the
splitting of molecules of electrolytes in solution.
Irrigation Spray - Irrigation by means of nozzles along a
pipe on the ground or from perforated overhead pipes.
Lagoon - (1 ) A shallow body of water as a pond or lake',
which usually has a shallow, restricted inlet from
the sea. (2) A pond containing raw or partially treated
wastewater in which aerobic or anaerobic stabilization
occurs .
Lime - Any of a family of chemicals consisting essentially
of calcium hydroxide made from limestone (calcite)
which is composed almost wholly of calcium carbonate
or a mixture of calcium and magnesium carbonates.
Liquor, Mixed - A mixture of activated sludge and sewage
in the aeration tank undergoing activated sludge
treatment.
Liquor, Supernatant - (1) The liquor overlying deposited
solids. C2) the liquid in a sludge digestion tank
which lies between the sludge at the bottom and the
floating scum at the top.
Loss of Head Gage - A gage on a rapid sand filter which
indicates the loss of head involved in the filtering
operation whereby the operator is able to ascertain
the need for filter backwashing.
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Macropore - The pores in activated carbon which are larger
(diameter) than 1 .OOOA.
Makeup Carbon - Fresh granular activated carbon which must
be added to a column system after a regeneration cycle
or when deemed necessary to bring the total amount of
carbon to specification.
Manometer - An instrument for measuring pressure. It
usually consists of a U-shaped tube containing a
liquid the surface of which is one end of the tube
moves proportionally with changes in pressure on
the liquid in the other end. Also, a tube type of
differential pressure gauge.
Mean Veloci ty - The average velocity of a stream flowing in
a channel or conduit at a given cross section or in a
given reach. It is equal to the discharge divided by
the cross sectional area of the reach. Also called
average velocity.
Mesh Size (Activated Carbon).- The particle size of granular
activated carbon as determined by the U.S. Sieve series.
Particle size distribution within a mesh series is
given in the specification of the particular carbon.
Methylene Blue Number (Activated Carbon) - The methylene
blue number is the milligrams of methylene blue
adsorbed by 1 gram of carbon in equilibrium with a
solution of methylene blue having a concentration
of 1 .0 mg/1 .
Methylorange Alkalinity - A measure of the total alkalinity
of an aqueous suspension or solution. It is measured
by the quantity of sulfuric acid required to bring the
water pH to a value of 4.3 as indicated by the change
in color of methyl orange. It is expressed in mili-
grams CaCOs' per 1 i ter.
Mi cropore - The pores in activated carbon which range in
size (diameter) from 10 to 1,000 A.
Mi 11igrams Per Liter (mg/1) - This is a weight per volume
designation used in water and wastewater analysis.
Mixed Media Filtration - A filter which uses 2 or more filter
materials of differing specific gravities selected so
as to produce a filter uniformly graded from coarse
fine.
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DRAFT
Monitoring - (1) The procedure or operation of locating
and measuring radioactive contamination by means of
survey instruments that can detect and measure, as
dose rate, ionizing radiations. (2) The measurements
sometimes continous, of water quality.
Most Probable Number (MPN) - That number of organisms per
unit volume that, in accordance with statistical
theory, would be more likely than any other number
to yield the obserbed test result with the greatest
frequency. Expressed as the organisms per
100 ml. Results are computed from the number of
positive findings of coliform-group organisms result-
ing from multiple-portion decimal-di1ution plantings.
Nappe - The sheet or curtain of water overflowing a weir
or dam. When freely overflowing any given structure,
it has a well-defined upper and lower surface.
Neutralization - Reaction of acid or alkali with the
opposite reagent until the concentrations of hydrogen
and hydroxyl ions in solution are approximately equal.
Ni tri fication - The conversion of nitrogenous matter into
nitrates by bacteria.
Nonionic Surfactant - A general family of surfactants so
called because in solution the entire molecule
remains associated. Nonionic molecules orient them-
selves at surfaces not by an electrical charge, but
through separate grease-solubi1izing and water-soluble
groups within the molecule.
Nonsettleable Matter - The suspended matter which does not
settle nor float to the surface of water in a period
of one hour.
Nonsettleable Solids - Wastewater matter that will stay in
suspension for an extended period of time. Such
period may be arbitrarily taken for testing purposes
as one hour.
Notch - An opening in a dam, spillway, or measuring weir
for the passage of water.
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DRAFT
Nozzle - (1) A short, cone-shaped tube used as an outlet
for a nose or pipe. The velocity of the merging
stream of water is increased by the reduction in
cross sectional area of the nozzle (2) a short piece
of pipe with a flange on one end and a saddle flange
on the other end.
Nutrients - Materials which are considered to be essential
to support biological life.
Odor Control - The elimination of odor-causing valatile
substances associated with organic matter, living
organisms, and cases. The most common, control
measurement in use are the application of activated
carbon residual chlorination, chlorine dioxide, ozone
and aeration.
Odor Threshold - The point at which after successive dilu-
tions with odorless water, the odor of a water sample
can just be detected. The threshold odor is expressed
quantitatively by the number of times the sample is
diluted with odorless water.
Oil and Grease - Those materials which are extractable from
wastewater with hexane, chloroform if other content of
these specific solvents pollutants in water or waste-
water (in mg/1 or ppm) which can significantly influence
the environment.
Open-Channel Flow - Flow of a fluid with its surface exposed
to the atmosphere. The conduit may be an open channel
or a closed conduit flowing partly full.
Operators Qualifications, Treatment Plant - Usually defined
by a licence issued by local authorities.
Organic Matter - Chemical substances of animal or vegetable
origin, or more correctly of basically carbon struc-
ture, comprising compounds consisting of hydrocarbons
and their deviations.
Organic Nitrogen - Nitrogen combined in organic molecules
such as protein, amines, and amino acids.
Orifice - (1) An opening with closed perimeter, usually of
regular form, in a plate, wall, or partition, through
which water may flow generally used for the purpose
of measurement or control of such water. The edge
may be sharp or of another configuration (2) the end
of a small tube such as a Pitot tube.
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DRAFT
Orifice Plate - A plate containing an orifice. In pipes,
the plate is usually inserted between a pair of
flanges, and the orifice is smaller in area than the
cross section of the pipe.
Orthophosphate - An acid or salt containing phosphorus
as P04.
Outfal1 - The point or location where sewage or drainage
discharges from a sewer, drain, or conduit.
Overflow Storm - A weir, orifice, or other device for
permitting the discharge from .a combined sewer of that
part of the flow in excess of that which the sewer
is designed to carry.
Oxidation - The addition of oxygen to a compound. More
generally, any reaction which involves the loss of
electrons from an atom.
Oxidation Pond - A basin used for retention of wastewater
before final disposal, in which biological oxidation
of organic material is effected by natural or
artifically accelerated transfer of oxygen to the
water from air.
Oxidation Reduction Potential (ORP) - The potential required
to transfer electrons from the oxidant to the reductant
and used as a qualitative measure of the state of
oxidation in wastewater treatment systems.
Oxygen Consumed - The quantity of oxygen taken up from
potassium permananganate in solution by a liquid
containing organic matter. Commonly regarded as an
index of the carbonaceous matter present. Time and
temperature must be specified.
Oxygen Dissolved - Usually designated as DO. The oxygen
dissolved in sewage water, or other liquid usually
expressed in parts per million or percent of satura-
tion.
Ozone - Oxygen in molecular form with three atoms of oxygen
forming each molecule. Atmospheric oxygen is in
molecular form but each molecule contains two atoms
of oxygen. Ozone is formed by passing high voltage
electric charges through dry air. The third atom
of oxygen in each molecule of ozone is loosely bound
to it and is easily released.
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DRAFT
Parshall Flume - A calibrated device developed by Parshall
for measuring the flow of liquid in an open conduit.
It consists essentially of a contracting length, a
throat, and an expanding length. At the throat is
a sill over which the flow passes as critical depth.
The upper and lower heads are each measured at a
definite distance from the sill. The lower head
not be measured unless the sill is submerged more than
about 67 percent.
Pathogenic Bacteria - Bacteria which may cause disease in
the organisms by their parasitic growth.
- The reciprocal of the logarithm of the hydrogen ion
concentration. The concentration is the weight of
hydrogen ions, in grams per liter of solution. Neutral
water, for example, has a pH value of 7 and hydrogen
ion concentration of 10.7.
pH Adjustment - A means of maintaining the optimum pH
through the use of chemical additives. Can be manual
or automatic, or automatic with flow corrections pH
adjustment is not a linear function.
Phenolein Alkalinity - A measure of the hydroxides
plus one half of the normal carbonates in aqueous
suspension. Measured by the amount of sulfuric acid
required to bring the water to a pH value of 8.3,
as indicated by a change in color of phenolphthalein.
It is expressed in parts per million of calcium
carbonate.
Pitot Tube - A device for measuring the velocity of flowing
fluid by using the velocity head of the stream as an
index velocity. It consists essentially of an orifice
held to point upstream and connected with a tube in
which the impact pressure due to velocity head may be
observed and measured. It also may be constructed with
an upstream and downstream orifice, or with an orifice
pointing upstream to measure the velocity head or
pressure and piezometer holes in a coaxial tube to
measure the static head or pressure, in which case the
difference in pressure is the index of velocity.
Pollution Load - A measure of the strength of a wastewater
in terms of its solids or oxygen-demanding characteris-
tics, or in terms of harm ,to receiving waters.
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DRAFT
Pollution Water - The Introduction into a body of water
of substances of such character and of such quantity
that its natural quality is so altered as to impair
its usefulness or render it offensive to the senses
of sight, taste, or smell.
Polyelectrolytes - Used as a coagulant or a coagulant aid
in water and wastewater treatment (activated carbon
is another coagulant aid). They are synthetic poly-
mers having a high molecular weight. Anionic negative-
ly charged. Nonionic carry both negative and positive
charges,(Cationic postively charged (most popular).
Pond, Sewage Oxidation - A pond either natural or artifical
into which partly treated sewage or discharged and in
which natural purification processes take place under
the influence of sunlight and air.
Pooling, Filter - The formation of pools of sewage on the
surface of filters, caused by surface cloggings.
Pore Volume (activated carbon) - The pore volume is the
difference in the volumetric displacement by granular
activated carbon in mercury and in helium at standard
conditions.
Preaeration - A preparatory treatment of sewage consisting
of aeration to remove gases, add oxygen, or promote
flotation of grease and aid coagulation.
Prechlorination - (1) Chlorination of water prior to filtra-
tion. (2) Chlorination of sewage prior to treatment.
Precipitation, chemical - (1) Precipitation induced by
addition of chemicals (2) The process of softening
water by the addition of lime and soda ash as the
precipitants .
Pretreatment - Any wastewater treatment process used to
reduce pollution load partially before the wastewater
is introduced into a main sewer system or delivered
to a treatment plant "for substantial reduction of the
pollution load.
Primary Treatment - A process to remove substantially all
floating and settl eabl esol ids in wastewater and
partially to reduce the concentration of suspended
solids.
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DRAFT
Probability Curve - A curve that expresses the cumulative
frequency of occurrence of a given event, based on an
extended record of past occurrences. The curve is
usually plotted on specially prepared coordinate paper,
with ordinates representing magnitude equal to, or
less than, the event, and abscissas representing the
probability, time, or other units of incidence.
Process Activated Sludge - A biological sewage treatment
process in which a mixture of sewage and activated
sludge is agitated and aerated. The activated sludge
is subsequentlyseparated from the treated sewage
(mixed liquor) by sedimentation, and wasted or returned
to the process as needed. The treated sewage overflows
the weir of the settling tank in which separation from
the sludge takes place.
Process. Biological - The process by which the life activities
of bacteria, and other microorganisms in thesearch for
food break down complex organic materials into simple,
more stable substances. Self-purification of sewage
polluted streams, sludge digestion, and all so-called
secondary sewage treatments result from this process.
Also called biochemical process.
Process, Oxidation - Any method of sewage treatment for the
oxidation of the putrescible organic matter the usual
methods are biological filtration, and the activated
sludge process.
Purification Degree - (1 ) A measure of the completeness of
destruction or removal of objectionable impurities.
such as bacteria and hardness from water by natural
means (selfpurifications)or by treatment (2) A
measure of the removal, oxidation, or destruction of
solids organic matter, bacteria, or other specified
substance effected by sewage treatment processes.
Putrefaction - Biological decomposition of organic matter
~~ accompanied by the production of foul-smel 1 ing as-
sociated with anaerobic conditions.
Rate Oxidation - The rate at which the organic matter in
sewage is stablized.
Ratio Dosing - The maximum rate of application of sewage
to a filter on any unit of area, divided by the average
rate of application on, that area.
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DRAFT
Reactivation (activated carbon) - The removal of adsorbates
from spent granular activated carbon which will allow
the carbon to be reused. This is also called regen-
eration and revivification.
Reaeration Sludge - The continous aeration of sludge after
its intial aeration in the activated sludge process.
Recirculation - The refiltration of all or a portion of the
effluent in a high rate trickling filter for the pur-
pose of incoming flow to reduce its strength.
Reduction Overall - The percentage reduction in the final
effluent as compared with the raw sewage.
Reoxygenation - The replenishment of oxygen in a stream
from (1 ) dilution water entering the stream (2) bio-
logical oxygenation through the activities of certain
oxygen producting plants and (3) atmospheric reaera-
tion.
Reservoir - A pond, lake, tank, basin, or other space
either natural in origin or created in whole or in
part by building of engineering structures. It is
used for storage, regulation, and control of water.
Recorder - A device that makes a graph or other automatic
record of the stage, pressure, depth, velocity, or
the movement or position of water controlling devices,
usually as a function of time.
Recovery Products - Substances regarded as wastewater
pollutants which are recovered for their potential
value through sale or reuse; recovery often is used
•to lower or partially offset treatment (or recovery)
costs.
Rectangular Weir - A weir having a notch that is rectangu-
lar in shape.
Reduction Practices - (1) Wastewater reduction practices
can mean the reduction of water usage to lower the
volume of wastewater requiring treatment and (2) the
use of chemical reductant materials to lower the
valance state of a specific wastewater pollutant.
Reduction Treatment - The opposite of oxidation treatment
where in a reductant (chemical) is used to lower the
valence state of a pollutant to a less toxic form
e.g. the use of S02 to "reduce" chromium +6 to
chromium +3 in an acidic solution.
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DRAFT
Refractory Organics - Organic pollutants which are chemically
quite stable or resistant to treatment or biological
oxidation, e.g. DDT pesticide.
Residual Chlorine - Chlorine remaining in water or waste-
water at the end of specified contact period as
combined or free chlorine.
Salinity - (1) The relative concentration of salts, usually
sodium chloride, in a given water. It is usually
expressed in terms of the number of parts per million
of chloride (Cl ) . (2) A measure of the concentration
of dissolved mineral substances in water.
Sampler - A device used with or without flow measurement
to obtain an aliquot portion of water or waste for
analytical purposes. May be designed for taking a
single sample (grab), composite sample, continous
sample, periodic sample.
Sanitary Sewer - A sewer that carries liquid and water-
carried wastes from residences, commercial buildings,
industrial plants, and institutions together with
minor quantities of ground-storm, and surface waters
that are not admitted intentionally.
Screen - (1) A device with openings, generally of uniform
size, used to retain or remove suspended or floating
solids in flowing water or wastewater and to prevent
them from entering an intake or passing a given point
in a conduit. The screening element may consist of
parallel bars, rods, wires, grating, wire mesh, or
perforated plate, and the openings may be of any
shape, although they are usually circular or rectangular
(2) A device used to segregate granular material such
as sand, crushed rock, and soil into various sizes.
Secondary Settling Tank - A tank through which effluent
from some prior treatment process flows for the
purpose of removing settleable solids.
Secondary Wastewater Treatment - The treatment of wastewater
by biological methods after primary treatment by sedi-
mentation .
Second Stage Biological Oxygen Demand - That part of the
oxygen demand associated with the biochemical oxida-
tion of nitrogenous material. As the term implies, the
oxidation of the nitrogenous materials usually does
not start until a portion of the carbonaceous material
has been oxidized during the first stage.
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DRAFT
Sedimentation - The process of subsidence and deposition
of suspended matter carried by water, wastewater, or
other liquids, by gravity. It is usally accomplished
by reducing the velocity of the liquid below the point
at which it can transport the suspended material.
Also called settling.
Seeding Sludge - The inoculation of undigested sewage solids
with sludge that has undergone decomposition for the
purpose of introducing favorable organisms, thereby
accelerating the intial stages of digestion.
Sewage Combined - A sewage containing both sanitary sewage
and surface or storm water with or without industrial
wastes.
150 ppm of
Sewage Dilute - Sewage containing less than
suspended solids and BOD (weak sewage).
Sewage Industrial - Sewage in which industrial wastes pre-
dominate.
Sewage Raw - Sewage prior to receiving any treatment.
Sewage Settled - Sewage from which most of the settleable
solids have been removed by sedimentation.
Sewage Storm - Liquid flowing in sewers during or following
a period of heavy rainfall and resulting therefrom.
Sewer - A pipe or conduit, generally closed, but normally
not flowing full for carrying sewage and other waste
liquids.
Sewer Intercepting - A sewer which receives dry-weather
flow from a number of transverse sewers or outlets,
and fequently additional, predetermined quantities of
storm water (if from a combined system) and which
conducts such waters to a point for treatment or dis-
posal .
Semipermeable Membrane - A barrier, usually thin, that per-
mits passage of particles up to a certain size or of
special nature. Often used to separate colloids from
their suspending liquid, as in dialysis.
B-30
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DRAFT
Settleabl e Sol ids - (1) That matter in wastewater which will
not stay in suspension during a preselected settling
period, such as one hour, but either settles to the
bottom or floats to the top. (2) In the Imhoff cone
test, the volume of matter that settles to the bottom
of the cone in one hour.
Skimming Tank - A tank so designed that floating matter will
rise and remain on the surface of the wastewater until
removed, while the liquid discharges continously under
certain walls or scum boards.
SIudge - The solids (and accompanying water and organic
matter) which are separated from sewage or industrial
wastewater in treatment plant facilities. Sludge
separation and disposal is one of the major expenses
in wastewater treatment.
Sludge Conditioning - A process employed to prepare sludge
for final disposal can be thickening, digesting, heat
treatment etc.
Sludge Digestion - The process by which orqanic or volatile
matter in sludge is gasified, 1iquified , mineralized,
or converted into more stable organic matter through
the activities of either anaerobic or aerobic organisms
Sludge Disposal - The final disposal of solid wastes includ-
ing the use of sewage sludges as fertilizers and soil
builders; dumping sludge at sea; and filling low-
lying lands.
Sludge thickening - The increase'in solids concentration
of sludge in a sedimentation or digestion tank.
Spills - A chemical or material spill is an unintentional
discharge of more than 10 percent of the sewage daily
usage of a regularly used substance. In the case
of a rarely used (one per year or less) chemical or
substance, a spill is that amount that would result
in 10% added loading to the normal air, water or solid
waste loadings measured as the closest equivalent
pollutant.
Stabilization Lagoon - A shallow pond for storage of waste-
water before discharge. Such lagoons may serve only
to detain and equalize wastewater composition before
regulated discharge to a stream, but often they are
used for biological oxidation.
B-31
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DRAFT
Stabilization Pond - A type of oxidation pond in which
biological oxidation of organic matter is effected
by natural or artifically accelerated transfer of
oxygen to the water from air.
Staff Gauge - A graduated scale, vertical unless otherwise
specified, on a plank, metal plate, pier, wall etc.,
used to indicate the height of a fluid surface above
a specified point or datum plane.
.Stage Discharge Relation - The relation between gauge height
and discharge of a stream or conduit at a gauging
station. This relation is shown by the rating curve
or rating table for such stations.
Static Head - (1) The total head without reduction for
velocity head or losses; for example, the difference
in the elevation of headwater and tail water of a
power plant. (2) The vertical distance between the
free level of the source of supply and the point of
free discharge or the level of the free surface.
Steady Flow - (1} A flow in which the rate or quantity of
water passing a given point per unit of time remains
constrant. (2) Flow in which the velocity vector does
not change in either magnitude or direction with
respect to time at any point or section.
Steady Uniform Flow - A flow in which the velocity and the
quantity of water flowing per unit remains constant.
«
Stilling Well - A pipe, chamber, or compartment with com-
partively small inlet or inlets communicating with a
main body of water. Its purpose is to dampen waves
or surges, while permitting the water level within
the well to rise and fall with the major fluctations
of the main body of water. It is used with water-
measuring devices to improve accuracy of measurement.
Submerged Weir - A weir that when in use, has the water
level on the downstream side at an elevation equal
to or higher than, the weir crest. The rate of dis-
charge is affected by the tail water. Also called
drowned weir.
Suppressed Weir - A weir with one or both sides flush with
the channel of approach. This prevents contraction
of the nappe adjacent to the flush side. The suppres-
sion may occur on one end or both ends.
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DRAFT
Surveys - The gathering of numerical and other forms of
data from the field, or plant site for the subsequent
purpose of data reduction, correlation and analysis
leading to improve water supply, treatment, use and
wastewater treatment, described in total as a Water
Management Program.
Suspended Matter - (1) Solids in suspension in water,
wastewater or effluent. (2) Solids in suspension
that can be removed readily by standard filtering
procedures in a laboratory.
Suspended Sol ids - (1) Solids that either float on the
surface of, or are in suspension in water, wastewater,
or other liquids, and which are largely removable by
laboratory filtering. (2) The quantity of material
removed from wastewater in a laboratory test, as
prescribed in "Standard Methods for the Examination
of Water and Wastewater" and referred to as non-
filterable residue.
Tertiary Treatment - A process to remove practically all
solids and organic matter from wastewater. Granular
activated carbon filtration is a tertiary treatment
process. Phosphate removal by chemical coagulation
is also regarded as a step in tertiary treatment.
Threshold Odor - The minimum odor of the water sample that
can just be detected after successive dilutions with
odorless water. Also called odor threshold.
Titra.tion - The determination of a constituent in a known
volume of solution by the measured addition of a solu-
tion of known strength to completion of the reaction
as signaled by observation of an end point.
Total Organic Carbon (TOG) - TOC is a measure of the amount
of carbon in a sample originating from organic matter
only. The test is run by burning the sample and
measuring the CO produced.
Total Solids - The total amount of solids in a waste water
in both solution and suspension.
Tracer - (1) A foreign substance mixed with or attached to
a given substance for the determination of the loca-
tion or distribution of the substance. (2) An element
or compound that has been made radioactive so that it
can be easily folio-wed (traced) in biological and
industrial processes. Radiation emitted by the
radioisotope pinpoints its location.
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DRAFT
Treatment Efficiency - Usually refers to the percentage
reduction of a specific or group of pollutants by a
specific wastewater treatment step or treatment plant.
Turbidmeter - An instrument for measurement of turbidity, in
which a standard suspension usually is used for
reference.
Turbidity - (1) A condition in water or wastewater caused
by the presence of suspended matter, resulting in the
scattering and absorption of light rays. (2) A measure
of fine suspended matter in liquids. (3) An analytical
quantity usually reported in arbitrary turbidity units
determined by measurements of light diffraction.
Turbulent Flow - (1) The flow of a liquid past an object
such that the velocity at any fixed point in the fluid
varies irregularly. (2) A type of liquid flow in which
there is an unsteady motion of the particles and the
motion at a fixed point varies in no definite manner.
Sometimes called eddy flow, sinuous flow.
Ultimate Biochemical Oxygen Demand - (1) Commonly, the total
quantity of oxygen required to satisfy completely the
first-stage biochemical oxygen demand. (2) More strickly,
the quantity of oxygen required to statisfy completly
both the first-stage and the second-stage biochemical
oxygen demands.
Velocity Area Method - A method used to determine the dis-
charge of a stream or any open channel by measuring
the velocity of the flowing water at several points
within the cross section of the stream and summing up
the products of these velocities and their respective
fraction of the total area.
Velocity Meter - A water meter that operates on the prin-
ciple that the vanes of the wheel move at approximately
the same velocity as the flowing water.
Velocity of Approach - The mean velocity in a conduit im-
mediately upstream from a weir, dam, venturi tube,
or other structure.
Vena Contracta - The most contacted sectional area of a
stream jet, or nappe issuing through or over an orifice
or weir notch. It occurs downstream from the plane
of such notch or orifice.
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DRAFT
Venturi Flume - A open flume with a contracted throat that
causes a drop in the hydraulic grade line. It is used
for measuring flow.
Venturi Meter - A differential meter for measuring flow of
water or other fluid through closed conduits of pipes,
consisting of a venturi tube and one of several pro-
prietary forms of flow-registering devices. The dif-
ference in velocity heads between the entrance and the
contracted throat is an indication of the rate of
flow.
Venturi Tube - A closed conduit or pipe, used to measure
the rate of fluids, containing a gradual contraction
to a throat, which causes a pressure-head reduction
by which the velocity may be determined. The con-
traction is usually, but not necessarily, followed by
an enlargement to the original size.
Volatile Sol ids - The quantity of solids in water, waste-
water or other liquids, lost on ignition of the
dry sol ids at 600°C.
Wastewater Survey - An investigation of the quality and
characteristics of each waste stream, as in an industrial
plant or municipality.
Water Level Recorder - A device for producing, graphically
or otherwise, a record of the rise and fall of a water
surface with respect to time.
Water Meter - A device installed in a pipe under pressure
for measuring and registering the quantity of water
passing through it.
Water Renovation - Wastewater treatment of sufficient degree
to allow the reuse of water for one or more purposes
in a given water supply/treatment system.
Neir - (1) A diversion dam. (2) A device that has a crest
and some side containment of known geometric shape,
such as a V, trapezoid, or rectangle and is used to
measure flow of liquid. The liquid surface is exposed
to the atmosphere. Flow is related to upstream height
of water above the crest, to position of crest with
respect to downstream water surface, and to geometry
of the weir opening.
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DRAFT
APPENDIX C
EFFECT OF POLLUTANT PARAMETERS ON
TREATMENT WORKS
pH, ACIDITY AND ALKALINITY
Most bacteria (and other protists) that are essential to the
operation of a biological treatment system cannot bear pH
levels above 9.5 or below 5.0. The pH range for optimum
growth generally lies between 6.5 and 7.5. Depending on the
volume of a particular waste and the acidity or alkalinity
of the waste in the treatment unit, an incoming waste of
extreme pH could have a substantial adverse effect on a
treatment unit.
Acidity
Highly acid wastes can exhibit
on microorganisms as wastes of
incoming waste is particularly
anaerobic digesters, where the
6.6 to 7.6. An incoming waste
the pH of an anaerobic system
the same detrimental effects
low pH. The acidity of an
important in operation of
pH for optimum operation is
of high acidity that causes
to drop below 6.2 will severely
upset operation of the unit. Wastes of high acidity are
also corrosive to the metals and concrete that make up the
structure of any treatment unit.
Alkalini ty
A waste of high alkalinity can have a severe effect on the
operation of a treatment unit, not only causing the death of
microorganisms, but also causing the corrosion of structural
materials.
OIL AND GREASE
Oils and grease can cause problems with scum formation in
wet wells and clarifiers. Mineral oils in particular can
coat solid particles that are present in wastes. The
particles hinder biological activity and increase maintenance
problems. Free oil (as measured by CCH extraction) has
reportedly interfered with aerobic biological treatment
at concentrations of 50-100 mg/1 (1).
C-l
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DRAFT
CHEMICAL OXYGEN DEMAND (COD)
Since the COD analysis is sensitive to compounds that are
toxic to biological life as well as those that are not, a
waste of high COD can be potentially harmful to treatment
systems if toxins are present. The potential for harm of a
high COD waste would remain unknown without either detailed
chemical analysis of the waste or experimentation with the
waste on a laboratory-scale biological treatment system.
CHROMIUM (Cr)
Moore, et. aj_ (2)> nave studied the effects of hexavalent
chromium (in the form of potassium chromate) on
laboratory-scale activated sludge systems and laboratory
scale anaerobic digesters. Their results for activated
sludge systems showed that continuous Cr+6 concentrations
at and below 15 mg/1 in the sewage feed had no significant
effect on overall BOD and COD removal. A continuous dose
of 50 mg/1 of Cr+6_ reduced BOD removal efficiency by
three percent over that of a control unit and COD removal
efficiency by four percent, but the authors attach limited
significance to this result. Continuous doses of chromium
containing primary and secondary sludge from the activated
sludge system to the anaerobic digesters had no effect on
anaerobic gas production at concentrations of Cr+6 in the
sludge of 3.0 mg/1, 5.8 mg/1, and 30 mg/1.
The authors also studied the effects of slug doses of Cr+6
on the aforementioned .systems. The sludge doses were fed
to the activated sludge systems over a four hour period of
time in the amounts of 10 mg/1, 100 mg/1 and 500 mg/1. No
effect on performance was noted with the 10 mg/1 dose. The
100 mg/1 dose caused a drop of three percent in the BOD removal
efficiency and a greater drop in the COD removal efficiency,
with a rapid recovery. The 500 mg/1 dose caused a drop in
BOD removal efficiency of 11 percent and a drop in the
COD removal efficiency of 13 percent. The decreased
efficiency lasted for 32 hours, and was followed by a gradual
recovery. Slug doses were also added to digesters that had
previously received chromium containing sludge. A slug dose
of 300 mg/1 caused gas production to cease for seven days,
followed by gradual recovery. A slug dose of 500 mg/1
ceased gas production permanently. The authors point out
that the likelihood of digesters receiving slug doses of
these magnitudes is extremely remote.
C-2
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DRAFT
The authors' results also show that the removal efficiency
of chromium by the activated sludge process can vary greatly,
depending on the chromium concentration in the influent.
Reported Cr+6 removals varied from approximately 78 percent
to 17 percent when the Cr+6 influent concentration was
50.0 mg/1 to 0.5 mg/1 respectively.
Other researchers have performed studies on nitrification.
Whiteland, ejt aj_ (1), in a study of the effects of
hexavalent chromium on the nitrification process, have
reported that the process was severely affected at Cr+6
concentrations in raw sewage on the order of 2 mg/1 to
5 mg/1.
COPPER (Cu)
McDermott, e_t aj_ (2), have investigated the effects
of copper in the form of copper sulfate and in the form of
a copper cyanide complex (Nan. Cu(CN)n_) on bench scale
activated sludge systems and bench scale anaerobic digesters.
Studies were conducted on the effects of both continuous
and slug doses of these two forms of copper on BOD and COD
removal efficiency of the activated sludge systems, and on
the effects of continuous doses of copper sulfate, continuous
doses of copper cyanide complex, and slug doses of copper
sulfate on gas production from the anaerobic digesters.
The results for continuous doses to activated sludge systems
showed that 10-25 mg/1 of copper sulfate in the influent
reduced BOD and COD removal efficiency by an average of
four percent, and that 5-10 mg/1 of the copper cyanide
complex reduced BOD and COD removal efficiency by as much as
six percent. Differences in effects of the two forms of
copper disappeared after the system acclimated to the copper
and cyanide. Slug doses of copper sulfate to the activated
sludge system of 66 mg/1 over a four-hour period had only
a small effect on BOD and COD removal efficiency, but doses
of 100 mg/1 caused a 50 percent reduction in BOD removal
efficiency and larger doses up to 410 mg/1 had somewhat
greater effects. All of the systems recovered after a
maximum of 120 hours. Smaller slug doses of the copper
cyanide complex had a much more severe initial effect than
the copper sulfate, but the systems recovered in only 24 hours
with doses up to 25 mg/1. Anaerobic digesters that were fed
combined primary and secondary sludge from activated sludge
units that were receiving 10-25 mg/1 of copper sulfate and
10 mg/1 of the copper cyanide complex experienced subnormal
gas production. Slug doses of copper sulfate of as much as
410 mg/1 had no effect on digester performance. The authors
also report that the activated sludge process is 79 to 50
percent efficient in the removal of both forms of copper when
C-3
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DRAFT
the copper concentration in the influent is 0.4 to 25 mg/1.
Studies on the effect of copper on the nitrification process
have been conducted by Kalabina, e_t aj_ (1). The authors
report that copper at concentrations of 0.5 mg/1 inhibited
nitrification when the copper was fed in the form of copper
sulfate.
CYANIDE (CN)
It has been reported that 1.0-2.0 mg/1 of cyanide (as HCN)
in influent sewage had an effect on the performance of
activated sludge units, trickling filters, and anaerobic
digesters, and that 2.0 mg/1 of cyanide inhibited the
nitrification process. Higher levels of tolerance of
activated sludge units and trickling filters have been
reported by other authors. Interference with the activated
sludge process has been reported at cyanide concentrations
in raw sewage of 5 mg/1. Studies on trickling filter
performance have reported that 30 mg/1 of cyanide in the
influent to trickling filters produced an effluent of poor
quality, but that cyanide concentrations of 10 mg/1 can be
destroyed almost completely. Other studies have reported
that secondary biological treatment processes, if acclimatized
to cyanide, can effectively oxidize it (1).
IRON (Fe)
Iron is a necessary nutrient for microbial growth, and has no
effect on the activated sludge process except at very high
concentrations (on the order of 1000 mg/1). The effect of
iron on the sludge digestion process has been reported (to be
much greater. Iron levels above 5 mg/1 in digesters have
caused interference with the process, due to the release of
acidity when the iron is hydrolyzed (3).
NICKEL (Ni
McDermott, et_ al (2) have conducted studies on the
effect of nickel sulfate additions to bench scale activated
sludge units and anaerobic digesters. Continuous doses of
nickel to activated sludge units ranging from 2.5-10
mg/1 reduced BOD removal efficiency by a maximum of five
percent and increased the turbidity of the effluent. A
200 mg/1 slug dose of nickel seriously reduced treatment
efficiency for a few hours, but the activated sludge process
recovered completely within 40 hours. Combined primary and
secondary sludge from an activated sludge process receiving
C-4
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DRAFT
10 mg/1 of nickel digested satisfactorily in anaerobic
digesters, and primary sludge from a unit receiving
40 mg/1 continously digested satisfactorily. It was
reported that the activated sludge process is approximately
30 percent efficient in the removal of nickel.
With respect to nitrification, it has been reported that
severe inhibition of the process is experienced at a
nickel concentration of 0.5 mg/1 (1).
PHOSPHORUS (P)
Phosphorus is not harmful to treatment works, and is
actually a necessary nutrient for adequate bacterial
growth. If phosphorus is not completely removed during
wastewater treatment, however, it can have harmful effects
upon the receiving water (as discussed under Section VI).
ZINC (Zn)
McDermott, e_t_ aj_ (2), have reported the effects of
zinc on activated sludge treatment and anaerobic digestion.
Zinc sulfate and zinc complexed with cyanide had similar
effects when fed continously to a laboratory-scale
activated sludge process. At concentrations ranging from
2.5 to 20 mg/1 both substances reduced BOD removal
efficiency by a maximum of two percent after the activated
sludge became acclimated. The maximum zinc concentration
that will produce no significant effect on treatment
efficiency was reported as greater than 2.5 mg/1 and less
than 10 mg/1. A 160 mg/1 slug dose of zinc fed to the
activated sludge unit over a period of four hours caused
a drastic reduction in treatment efficiency for about one
day, but the unit recovered completely after 40 hours.
Combined primary and secondary sludge from activated
sludge units receiving 10 mg/1 of zinc continuously (as
Zn_S04.) digested suitably in anaerobic digesters. Sludge
from activated sludge units that were fed 20 mg/1 caused
rapid failure of the digestion units. The activated
sludge process is reported as being from 95 to 74 percent
efficient in removing zinc when fed sewage with zinc concen-
trations from 2.5 mg/1 to 20 mg/1 respectively.
Other authors have reported that the concentration of zinc
in influent sewage should be less than 5 mg/1 to prevent
decreases in gas production in anaerobic digestion,
and that zinc concentrations of 0.5 mg/1 will inhibit the
nitrification process (1).
C-5
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DRAFT
SYNERGISM AND ANTAGONISM
Synergism
The increase in the toxic effect of one substance caused by
the presence of another substance is called synergism.
Synergistic effects are particularly important when con-
sidering metals, since most metals are soluble at low pH
values and insoluble at high pH values. Thus acidity can
exert a synergistic effect by contributing to the release
of metals into solution, where they can be ingested by
mi croorganisms.
Reference 3 contains a discussion of the synergistic
effects of cadmium, chromium, copper, iron, and zinc,
which is summarized below:
Cadmi urn - Zinc and manganese have been reported to have
synergistic effects with cadmium. It is certain that acidity
would also have a synergistic effect.
Chromium - Iron, copper, and acidity have been reported to
have synergistic effects with chromium.
Copper - Synergism with cyanide, acidity, and other heavy
metals has been reported.
Iron - Synergism of iron with chromium has been reported
and synergistic effects with other metals may also occur.
Zi nc - Synergistic effects have been reported with the
following: 10 mg/1 of cadmium with 1 mg/1 of zinc, 10 mg/1
of cadmium with 10 mg/1 of zinc, and 100 mg/1 of manganese
with 10 mg/1 of zinc.
Antagoni sm
Antagonism is the opposite of synergism, and is thus the
decrease in the toxic effect of one substance caused by
the presence of another. Dramatic antagonistic effects
on metals are caused by chelating agents, of which EDTA
(disodium salt of ethylene diamine tetracetic acid) and
HEDTA (disodium salt of hydroxyethylenediamine triacetic
acid) are examples.
Sulfide can exhibit antagonistic effects with metals in
sludge digesters. This effect is probably responsible for
much of the ambiguity in the literature of the effects of
metals on sludge digestion. The, antagonistic effect
is due to the fact that sulfide precipitates metals, thus
taking them out of solution, and preventing their assimilation
by microorganisms. Other ions have similar effects on
C-6
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DRAFT
metals; examples are: hydroxide (high pH), chromate,
ferrocyanide, phosphate, carbonate, and arsenate (17).
A summary of the antagonistic effects of cadmium, copper,
and i ron follows: (3).
Cadmium - Sulfide and high pH (8 and higher) are antagonistic
wth cadmium.
Copper - Sulfide, high pH and certain chelating agents (such
as EDTA) are antagonistic with copper.
Iron - Sulfide and high pH are antagonistic with iron.
Additionally, an antagonistic effect would be expected with
cyanide, since the ferrocyanide complex is very stable.
C-7
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DRAFT
REFERENCES
U.S. Environmental Protection Agency, "Pretreatment
of pol1utants introduced i nto publicly-owned
treatment works, Office of Water Program Operations,
Washington, D.C., (October, 1973).
U.S. Department of Health, Education and Welfare,
Interaction of Heavy Metals and Biological Sewage
Treatment Processes, Public Health Service, Division
of Water Supply and Pollution Control, Cincinnati,
Ohio (May, 1975).
U.S. Environmental Protection Agency, State and Local
Pretreatment Programs, (Draft Federal Guidelines),
Office of Water Program Operations, Washington, D.C.,
(August, 1975).
r Q
0 - o
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APPENDIX D
METRIC UNITS
CONVERSION TABLE
MULTIPLY (ENGLISH UHITS)
ENGLISH UNIT ABBREVIATION
by TO OBTAIN (METRIC UNITS)
CONVERSION ABBREVIATION METRIC UNIT
ac
ac ft
BTU
acre
acre - feet
British Thermal
Unit
British Thermal
Unit/pound
cubic feet/minute
cubic feet/second
cubic feet
cubic feet
cubic inches
degree Fahrenheit
feet
gallon
gallon/minute
horsepower
Inches
inches of mercury
pounds
million gallons/day
mile
pound/square
inch (gauge)
square feet
square inches
tons (short)
yard
* Actual conversion, not a multiplier
0.405
1233.5
0.252
ha
cu m
kg cal
BTU/lb
cfm
cfs
cu ft
cu ft
cu in
F°
ft
gal
gpm
hp
in
in Hg
Ib
mgd
ml
pslg
sq ft
sq In
t
y
0.555
0.028
1.7
0.028
28.32
16.39
0.555(°F-32)*
0.3048
3.785
0.0631
0.7457
2.54
0.03342
0.454
3,785
1.609
(0.06805 psig +1)*
0.0929
6.452
0.907
0.9144
kg cal/kg
cu m/min
cu m/min
cu m
1
cu cm
°C
m
1
I/sec
kw
cm
atm
kg
cu m/day
km
atm
sq m
sq cm
kkg
m
hectares
cubic meters
kilogram - calories
kilogram calories/kilogram
cubic meters/minute
cubic meters/minute
cubic meters
liters
cable centimeters
degree Centigrade
meters
liters
liters/second
killowatts
centimeters
atmospheres
kilograms
cubic meters/day
kilometer
atmospheres (absolute)
square meters
square centimeters
metric tons (1000 kilograms)
meters
*U.S. GOVERNMENT PRINTING OFFICE:l
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