Environmental Protection Technology Series
COSTS OF RADIUM REMOVAL FROM
POTABLE WATER SUPPLIES
Municipal Environmental Research Laboratoi,
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to develop and
demonstrate instrumentation, equipment, and methodology to repair or prevent
environmental degradation from point and non-point sources of pollution. This
work provides the new or improved technology required for the control and
treatment of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-77-073
April 1977
COSTS OF RADIUM REMOVAL FROM
POTABLE WATER SUPPLIES
by
J. E. Singley1, B. A. Beaudet2,
W. E. Bolch1, and J. F. Palmer1
Department of Environmental Engineering Sciences
University of Florida
Gainesville, Florida 32611
2Water and Air Research, Inc.
Gainesville, Florida 32602
Grant No. EPAR803864-01
Project Officer
Gary S. Logsdon
Water Supply Research Division
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Municipal Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publica-
tion. Approval does not signify that the contents necessarily reflect the
views and policies of the U.S. Environmental Protection Agency, nor does men'
tion of trade names or commercial products constitute endorsement or recom-
mendation for use.
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FOREWORD
The Environmental Protection Agency was created because of increasing
public and government concern about the dangers of pollution to the health
and welfare of the American people. Noxious air, foul water, and spoiled
land are tragic testimony to the deterioration of our natural environment.
The complexity of that environment and the interplay between its components
require a concentrated and integrated attack on the problem.
Research and development is that necessary first step in problem
solution and it involves defining the problem, measuring its impact, and
searching for solutions. The Municipal Environmental Research Laboratory
develops new and improved technology and systems for the prevention,
treatment, and management of wastewater and solid and hazardous waste
pollutant discharges from municipal and community sources, for the preserva-
tion and treatment of public drinking water supplies, and to minimize the
adverse economic, social, health, and aesthetic effects of pollution. This
publication is one of the products of that research; a most vital communica-
tions link between the researcher and the user community.
This report estimates the capital and operating costs of removing radium
from public water supplies by lime-soda softening, ion exchange, and reverse
osmosis treatment methods. Cost of waste stream handling and ultimate
disposal are considered as well as treatment costs.
Francis T. Mayo, Director
Municipal Environmental Research
Laboratory
iii
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ABSTRACT
This report presents the results of an analysis of existing data from
various sources on the removal of radium from potable water supplies by lime-
soda softening, ion exchange, and reverse osmosis treatment methods. Remo-
val efficiency models are proposed for each process based on the compiled
data. These models are used to estimate the capital and annual operating
and maintenance costs for each water treatment process over a wide range of
raw water quality, raw water radium, and population conditions.
The radiological consequences of common methods of waste sludge and
brine disposal are discussed and waste volumes and activity levels of radium
in waste streams are estimated. The costs of ultimate disposal of the waste
streams produced by each process are estimated over the same raw water
quality and population ranges used to determine treatment costs.
This report is intended as a guide for planners and water utility
personnel in areas where the radium activity of potable water sources ex-
ceeds the limits set by EPA Drinking Water Regulations.
IV
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TABLE OF CONTENTS
Foreword •
Abstract iv
List of Figures vii
List of Tables xi
Acknowledgments xii
I. Introduction 1
Purpose of Report 1
Radium in Water Supplies ' . . . 1
Health Effects of Ingested Radium 2
Standards for Radium in Drinking Water 3
Removal of Radium from Water " 3
II. Conclusions 5
General. . . 5
Lime-Soda Softening 5
Ion Exchange 5
Reverse Osmosis 6
III. Recommendations 7
IV. Problems at Ultra-Low-Level Radioactive Wastes 8
V. Procedure and Cost Bases 12
Assumptions and Parameters 12
Source of Data 12
Assumed Radium Levels in Finished Waters 12
Raw Water Quality Parameters 13
Raw Water Radium and Water Quality 15
Required Removal Fraction for Radium 15
Population Ranges Studied 15
Cost Determinations 15
General 15
Basis of Cost Estimates 17
VI. Lime Soda Softening 20
General 20
Radium Removal in the Lime-Soda Process 21
Required Total Hardness Removal 26
Waste Streams., 26
Lime Sludge Production 30
Backwash Production 33
Methods for Lime Sludge Disposal 34
Discharge to Sewers 36
Discharge to Watercourse 37
Discharge to Sanitary Landfill 37
Permanent Lagoons 37
Temporary Lagoons 38
Mechanical Dewatering 39
Application to Man-made Depressions 39
v
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Methods of Lime Sludge Disposal (Continued) Page
Application to Farmland 39
Utilization as Raw Material 40
Disposal 41
Methods of Backwash Disposal 41
Discharge to Sewers 41
Discharge to Receiving Water 42
Holding Tanks, Lagoons, and Recycle 45
Treatment as a Nuclear Waste 47
Costs of Lime-Soda Treatment 47
Costs of Lime-Soda Waste Stream Disposal 47
Lagoons. 52
Gravity, Thickening. . 52
Mechanical Sludge Dewatering 55
Landfill 55
VII. Ion Exchange Softening 62
General ...... 62
Radium Removal in the Ion-Exchange Process 67
Required Treatment Fraction . 67
Brine Production. 69
Brine Disposal 72
Discharge to Sewers 74
Discharge to Watercourse 74
Evaporation Lagoons 74
Landspreading. . 76
Recycle of Brine 76
Brine Injection Wells 78
Treatment as a Nuclear Waste 79
Cost of Ion Exchange Softening 79
Cost of Brine Disposal 79
VIII. Reverse Osmosis 90
General 90
Radium Removal in Reverse Osmosis 94
Required Treatment Fraction 95
Radium in Reverse Osmosis Brines 99
Brine Disposal. 102
Discharge to Sewers 103
Discharge to Watercourse 103
Evaporation Lagoons 103
Landspreading 105
Brine Injection Wells 105
Treatment as a Nuclear Waste 105
Cost of Reverse Osmosis Softening 105
Brine Disposal Costs 108
IX. Unit Cost Curves 112
X. References ....... 116
Appendices
A. Blank. Computation Sheets 118
B. Sample Calculations - New Lime-Soda Plants 122
C. Sample Calculations - New Ion Exchange Plants 125
D. Sample Calculations - New Reverse Osmosis Plants 130
E. Sample Calculations - Upgrading Existing Facilities .... 133
107
F. Farmland Calculations -1--3'
vi
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FIGURES
Number Page
1 Required removal fraction for radium 16
2a Diagram of typical lime-soda treatment plant - Horizontal
flow plant 22
2b Diagram of typical lime-soda treatment plant - Solids
contact or upflow plant 23
3 Lime soda process, total hardness removal fraction vs.
radium removal fraction 24
4 Total hardness removal fraction as a function of raw
water radium content required to meet limit of 5.0 pCi/1
finished water 27
5 Finished water radium concentration versus raw water
radium concentration for lime-soda softening 28
6 Radium removal fraction vs. pH of treatment, lime-soda
process 29
7 Lime sludge production versus hardness removal for various
total dissolved solids 31
8 Backwash radium concentration, with lime-soda softening. . . 35
9 Radium in wastewater plant effluent if backwash or lime-
soda process is discharged to sanitary sewers 43
10 Approximate dilution requirements for backwash water,
lime-soda plants 46
11 Capital costs for lime-soda treatment 48
12 Annual operating costs, lime-soda process, RWR 7.5 pCi/1 . . 49
13 Annual operating costs, lime-soda process, RWR - 20 pCi/1. . 50
14 Annual operating costs, lime-soda process, RWR - 50 pCi/1. . 51
15 Unit cost of permanent lagoons, lime-soda plants 10 MGD
and under 53
vii
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FIGURES - Continued
Number Page
16 Unit cost of gravity thickening, lime-soda sludge
17 Unit cost of transporting 10 percent solids lime-soda
sludge by truck over a 5-mile one-way haul
18 Relative transportation cost for liquid organic sludges18. .
19 Unit cost of sanitary landfill, 10 percent solids lime-soda
sludge
20 Unit cost of sanitary landfill, 50 percent solids lime-soda
sludge 60
21 Diagram of typical ion exchange unit .....
22 Radium removal fraction vs. total hardness removal fraction
in ion exchange plants (before blending)
23 Mass balance for determining fraction of raw water to be
treated. . . ........... 66
24 Fraction of water needed to be treated as a function of
raw water radium concentration - ion exchange. .......
25 Generation of wastewater volumes with ion exchange
7 o
26 Radium in ion exchange waste waters (brine plus backwash). .
27 River water flow required to dilute ion exchange brine
to 5 pCi/1 75
28a Average rainfall - includes all forms of precipitation ...
28b Rate of evaporation indicates ability to evaporate, not
actual evaporation ....
80
29 Capital costs of ion exchange process, RWR = 7.5 pCi/1 . . .
ft 1
30 Capital costs of ion exchange process, RWR = 20 pCi/1. . . .
R?
31 Capital costs of ion exchange process, RWR = 50 pCi/1. . . .
32 Annual operating and maintenance costs of ion exchange,
RWR = 7.5 pCi/1
33 Annual operating and maintenance costs of ion exchange,
RWR = 20 pCi/1
viii
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FIGURES - Continued
Number Page
34 Annual operating and maintenance costs of ion exchange,
RWR = 50 pCi/1 85
35 Unit costs of waste disposal by lined evaporating ponds,
ion exchange
36 Unit cost of waste brine transmission; per mile of
pipeline, ion exchange
37 Unit cost of waste disposal by subsurface injection, ion
exchange
38a Osmosis - normal flow from low-concentration solution to
high-concentration solution.
38b Reverse osmosis - flow reversed, by application of pressure
to high-concentration solution27
9 7 92
39 Typical reverse osmosis system^'
40a Spiral-wound membrane configuration27 ^3
9 7 Q"}
40b Hollow fiber membrane configuration^' ..... 7J
41 Mass balance for determining fraction of raw water to be
treated
42 Fraction of water needed to be treated as a function of
98
97
raw water radium concentration - reverse osmosis
43 Detailed schematic of reverse osmosis process ........
44 Brine to finished water, reverse osmosis ...........
45 Radium concentration in brine, reverse osmosis
46 River water flow required to dilute reverse osmosis
brine to 5.0 pCi/1 ..................... 104
47 Capital costs of reverse osmosis treatment ......... 106
48 Annual operating and maintenance costs, reverse osmosis
Treatment ......................... 107
49 Unit cost of waste disposal by lined evaporating ponds,
reverse osmosis ...................... 109
ix
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FIGURES - Continued
Page
Number
50 Unit cost of waste brine transmission per mile of
pipeline, reverse osmosis 110
51 Unit cost of waste disposal by subsurface injection:
reverse osmosis Ill
52 Comparison of unit costs of water treatment, waste
disposal costs excluded, to meet radium standard of
5.p pCi/1 for RWR = 7.5 pCi/1 113
53 Comparison of unit costs of water treatment, waste
disposal costs excluded, to meet radium standard of
5.0 pCi/1 for RWR = 20 pCi/1 114
54 Comparison of unit costs of water treatment, waste
disposal costs excluded, to meet radium standard of
5.0 pCi/1 for RWR = 50 pCi/1 115
x
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TABLES
Number Page
1 Radiation Protection Standards Recommended by the
Federal Radiation Council 3
2 Raw Water Quality Concentrations Assumed for
Calculations 13
3 Correlation of Raw Water Quality Parameters with Radium. . . 14
4 Population and Flow Range Investigated 15
5 Chemical Prices Used in Calculations 18
6 Radium226 and Total Hardness Removal Efficiencies
Lime-Soda Softening 25
7 Lime-Soda Sludge Calculations 32
8 Typical Values of Lime Sludge Production and Radium
Concentration 33
9 -Ra content of selected rivers in the United States 44
10 The relationship of dewatering to other sludge treatment
processes for typical municipal sludges18 56
11 Radium removal in ion exchange plants 68
12 Radium removal in reverse osmosis plants 95
13 Brine volumes in reverse osmosis 102
xi
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ACKNOWLEDGMENTS
The authors would like to gratefully acknowledge the enthusiasm,
guidance, and encouragement of the many individuals who helped make this
project successful.
H. "Pete" Petry of R.E. Burton and Associates and Gary W. Kingzett of
Calgon Corporation were instrumental in providing important cost data and
assistance in writing the ion exchange section of the report. Paul L. Culler
of Basic Technologies, Inc., Manuel Vilaret of Black, Crow and Eidsness,
Inc. , and Tim Brodeur of Russell and Axon donated much of their time in the
seemingly endless search for technical and cost data.
Mr. Jimmy Ward prepared all the figures for the report and Pat Lee,
Shirley Johnson, Mary Ann Hester, Peggy Paschall, Kitty Hinton and Jeanne
Dorsey typed the final manuscript.
A special acknowledgment goes to the EPA Project Officer, Dr. Gary
Logsdon, for his technical and administrative direction, encouragement,
and unwavering enthusiasm throughout the project.
xii
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SECTION I
INTRODUCTION
PURPOSE OF REPORT
The purpose of this report is three-fold:
(1) to assemble existing data on the removal of radium from
public water supplies;
(2) to determine the costs of reducing radium to the proposed
interim standard of 5.0 pCi/1, including both capital and
operating costs for treatment, waste stream handling, and
ultimate waste disposal; and
(3) to identify areas in which further research will be required
in order to assist utilities in implementing the proposed
interim standard.
RADIUM IN WATER SUPPLIES
Radium is the element with atomic number eighty-eight and is the most
massive member of the alkaline earth metals or group IIA of the Periodic
Table. Other members of the alkaline earth metals are beryllium, magnesium,
calcium, strontium, and barium; these have a chemical behavior similar to
radium. Thus, radium will be transported in a manner similar to magnesium
and calcium; also, their destinations will be similar. For example, ingested
calcium and radium concentrate in the bones of humans.1
Radium is present in water as a naturally occurring element, primarily in
groundwaters and to a lesser extent in surface waters. Studies by Hursh2 on
the water supply sources of 41 cities in the U.S. showed that the average
22^Ra concentration of those municipal water supplies which utilized surface
sources was less than 0.3 pCi/1, ranging from 0.002 to 3.7 pCi/1. Numerous
studies on groundwater supplies in areas of radium bearing deposits have
demonstrated 226Ra concentrations in the range of about 0.5 pCi/1 to concen-
trations exceeding 50 pCi/1. The EPA3 has estimated that as many as 500
public water supplies exceed the 5.0 pCi/1 radium concentration.
Elevated levels of radium in groundwaters are thought to be caused by the
leaching of radium from radium-bearing rock strata into the deep sandstone
aquifers in Iowa and Illinois, and by leaching of radium from phosphate-rock
deposits found in parts of Florida into the Floridan Aquifer. Elevated radium
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levels have also been associated with surface run-off water in the vicinity of
uranium-rich deposits in Colorado and New Mexico.
Radium and other alkaline earth metals are not necessarily found in the
same place or in the same abundance. This is because radium that is found in
nature is a daughter or decay product in all three of the naturally occurring
radioactive series, each series eventually decaying to a stable isotope of
lead. For example, the 226Ra isotope is the fifth series progeny of 238U
(half-life, 4.51 billion years). Similarly, 228Ra and 224Ra are daughters
and the fourth series progeny of 232Th (half-life, 14.1 billion years). Both
224Ra and the 223Ra from the 235U chain are of little importance because of
their short half-lives, 3.64 days and 11.43 days, respectively. Because of
half-life differences in the parent, all daughters in equilibrium with a
•microgram of 238U will be at 0.334 picocuries. Similarly, all daughters in,
equilibrium with a microgram of 232Th will be 0.111 picocuries.
The importance and concentration of 226Ra and 228Ra in groundwaters can
be intuitively understood by simple examination of the distribution of uranium
and thorium in underground strata. Sedimentary rocks such as sandstones,
shales, and limestones have average uranium concentrations of 1.2-1.3 yg/g,
whereas thorium concentrations vary from 1.3 yg/g in limestones to 6 yg/g in
sandstones to 10 yg/g in shales. Thus, for example, a sandstone with 1.3 yg/g
of uranium and 6 yg/g of thorium would contain 0.434 pCi/g of uranium daugh-
ters at equilibrium. It should be evident that radium dissolved out of sedi-
mentary rocks could be about equally divided between 226Ra and 228Ra. However,
if transport is involved and the time scale is on the order of tens of years,
the 228Ra contribution would be greatly reduced by decay because of its 5.75
year half-life.
HEALTH EFFECTS OF INGESTED RADIUM
From the point of view of ionizing radiation delivered to man, the
isotopes 226Ra and 228Ra have about equal significance.4 226Ra, a member of
the uranium series, is an alpha particle emitter that decays with a half-life
of 1622 years, to 222Rn, a noble gas with a half-life of 3.82 days. The decay
of 222Rn is followed by a number of short-lived alpha and beta emitting daugh-
ters. 228Ra is a member of the thorium series. It is a 3-particle emitter
with a half-life of 5.75 years and decays through 228Ac to the alpha emitting
228Th. 228Th decays through a series of short-lived alpha and beta transi-
tions to 208Pb.
Both 226Ra and 228Ra concentrate primarily in the bones and skeletal
tissues and have been linked to increased human fatalities due to malignant
neoplasma , leukemia6 and other carcinomas6.
In 1961, the Federal Radiation Council published Radiation Protection
Guides (RPG) which set guidelines for total intake (from all sources, includ-
ing food and water) for 226Ra as follows7:
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TABLE 1. RADIATION PROTECTION STANDARDS RECOMMENDED BY THE FEDERAL RADIATION
COUNCIL
Nuclide Intake levels, pCi/day
Range I*Range litRange I11+
226Ra 0-2 2-20 20-200
* Calculations based on source information. Surveillance adequate to confirm
calculations.
t Surveillance adequate to demonstrate levels. Control at source to avoid
excess exposure as levels increase to top of Range II. Intakes do not
exceed the recommended Radiation Protection Guides (RPG).
+ Surveillance to check effect of control actions. Control designed to
reduce levels to Range II or lower. Intakes in Range III will result in
exposures exceeding RPG if continued for a sufficient period. .-. *
STANDARDS FOR RADIUM IN DRINKING WATER
The 1962 U. S. Public Health Service Drinking Water Standards listed a
maximum concentration of Ra in water used on interstate carriers of 3.0
pCi/18. Recognizing the health effects of ingestion of both 226Ra and 228Ra,
the U.S. Environmental Protection Agency has published Interim Primary Drink-
ing Water Regulations9, which include limits on radium as listed below:
Radionuclides Maximum Contaminant Level
226Ra + 228^ 5 pci/1
Gross Alpha Activity 15 pCi/1
(including 226Ra but
excluding radon and uranium)
If gross alpha activity exceeds 2 pCi/1 in those locations where 228Ra may be
present in drinking water, 226Ra analysis is required.
If 226Ra exceeds 3 pCi/1, analysis for 228Ra is required. Recommended
analytical techniques for each radionuclide of interest in the Interim Stand-
ards are published in Interim Radiochemical Methodology for Drinking Water,
Environmental Monitoring and Support Laboratory, EPA-600/4-75-008, U.S.E.P.A.,
Cincinnati, Ohio 452681°.
REMOVAL OF RADIUM FROM WATER
The water treatment plant is the point of control between radium
dissolved or suspended in raw water supplies and the consumer. In order to
meet the proposed interim standard of 5 pCi/1 in the most cost-effective
manner, it is important to understand how the treatment process affects the
level of radium in potable water.
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The major problem of concern in public water supplies is soluble radium
in groundwater supplies. Soluble radium exists in water as a divalent ion,
similar in chemical behavior to calcium and magnesium. Softening treatment
methods have been shown to be effective in removing 59-99 percent of dissolved
radium, as have membrane desalting methods. Coagulation without softening
may remove up to 25 percent of radium, however, the results are variable and
difficult to control.
The three methods selected for analysis in this report are:
(1) Lime and Lime-Soda Softening
(2) Ion Exchange Softening
(3) Reverse Osmosis
Radium removal efficiencies and associated operating data from water
treatment plants in Illinois, Iowa and Florida have been compiled and ana-
lyzed in this report. Removal efficiencies for each of the three treatment
methods, generalized plant flow diagrams, waste stream handling and disposal
methods, as well as associated costs of treatment and waste disposal are
reported for each type of plant in following sections of this report.
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SECTION II
CONCLUSIONS
GENERAL
No statistically significant correlation vas found between raw water
radium activity levels and other raw water quality parameters investigated,
although a trend toward significance was noted between radium and the heavy
metals,iron, barium, and boron.
LIME-SODA SOFTENING
Radium removal efficiencies of the six lime-soda softening plants in-
vestigated varied from 59-96 percent removal, averaging 80 percent. Radium
removal was found to vary with removal of total hardness according to a non-
linear relationship.
The majority of the radium activity removed during lime-soda treatment
appears in the waste sludge. The activity in the dry sludge approaches 105
pCi/kg and special consideration must be given to safe disposal of the con-
taminated sludge. Disposal of filter backwash water poses no particular
problem since the activity levels in this waste stream were found to be only
slightly higher than levels found in the raw water.
Lime-soda softening was shown to be a cost-effective method of treat-
ment for reducing radium levels to meet Federal Drinking Water Standards,
particularly for plants larger than 10 MGD capacity.
ION EXCHANGE
Investigation of radium removal at eight ion exchange plants demonstra-
ted that 95 percent or greater efficiencies can be expected from a well-
operated plant. Plants operated past the normal breakthrough point or
plants which were incompletely regenerating their exchange media continued
to remove 65-85 percent of the influent radium activity.
The majority of radium activity removed in the ion exchange process
appears in the regenerant brine effluent at levels approaching 103 pCi/1.
Approximately 9 percent of the radium activity remains in the exchange
medium and is not regenerated by normal means. Disposal methods for spent
brine may more often be limited by considerations of salinity rather than
radium activity levels.
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Ion exchange was shown to be a cost-effective method of reducing radium
levels to meet EPA Drinking Water Regulations, particularly at plant
capacities below 10 MGD.
REVERSE OSMOSIS
Investigation of radium removal at two reverse osmosis plants demon-
strated that 95 percent or greater efficiencies can be expected from a well-
operated plant. Radium activity levels in reject brine from reverse osmosis
plants are lower than those of ion exchange plants, however, reject brine
volumes are much higher. Disposal techniques may more often be limited by
considerations of salinity rather than radium activity levels.
Costs of reverse osmosis treatment were higher than for the other
methods investigated and it is expected that reverse osmosis will be limited
to applications in which the raw water is quite brackish or where the raw
water radium is extremely high.
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SECTION III
RECOMMENDATIONS
The radium removal models presented in this report are based on radium
analyses of raw and finished water taken during normal plant operation. The
radium removal efficiencies reported are incident to operation of the plant
to meet other water quality criteria. The present data, therefore, do not
reflect any attempt to optimize radium removal by relating radium removal
efficiency with other operating parameters, such as pH of treatment, deten-
tion time in clarification during lime-soda softening, optimum brine con-
centration of regenerating salt in ion exchange, etc. This is particularly
true for the lime-soda softening process. The range of radium removal ef-
ficiencies of the lime-soda plants studied in this report ranged from 59-96
percent. Pilot plant or full scale plant testing could establish the opti-
mum operating characteristics for consistent removal of radium nearer the
upper limit of the range.
Ion exchange and reverse osmosis are better defined in terms of relat-
ing removal efficiency of radium to removal of total hardness or total
solids. There are, however, some unresolved questions which further study
could help to answer.
In ion exchange, for instance, what are the long term effects of radium
upon the media? Is the radium completely regenerated from the media or is
there a build-up of radioactivity? If there is a build-up of radioactivity,
can it be periodically removed by regeneration with acid or other chemicals?
Since the radium removal model for reverse osmosis was formulated from
the operating data from only two plants, more full scale studies of this
process should be conducted before its use in radium removal is completely
endorsed.
Radiological implications of waste stream disposal were arrived at in
this report by calculating activities developed from a mass balance of radium
reported by investigators in radium removal studies of the three treatment
processes. On-site investigations at landfills, sludge lagoons, brine hold-
ing ponds, reclaimed land, and other sites where radium-rich wastes have
been disposed of for long periods of time should be carefully conducted to
determine the accuracy of the generalizations made in this report.
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SECTION IV
PROBLEMS OF ULTRA LOW-LEVEL RADIOACTIVE WASTES
In the evolution of the nuclear industry a convenient rule-of-thumb
classification of radioactive wastes developed. High level radioactive
wastes were those that contained curies per liter, intermediate level
wastes were those that contained millicuries per liter, and low level
wastes were those that contained microcuries per liter. It was very
obvious that high-level wastes needed very special treatment, normally in
the form of concentration before complete containment. These wastes were
often handled at a site remote from where they were generated. Historically,
intermediate-level wastes may have received treatment of some form at the
site of production and often the underlying principle was delay for decay.
Lastly, low-level wastes were "treated" by the principal of dilute and dis-
pense. Often the transport phenomena was mathematically considered in order
to predict the final environmental concentration.
Wastes which contained activites on the order of nanocuries per liter or
less were considered ultra-low level wastes and often were released without
consideration. These rules-of-thumb and treatment principals have subsequent-
ly experienced changes in philosophy.
Because each radioactive isotope has a unique combination of radiologi-
cal properties and because the effects on man are a function of these proper-
ties, standards evolved for each isotope. For example, the International
Committee for Radiation Protection (ICRP) gave maximum permissible concentra-
tions (MFC) for soluble and insoluble 226Ra for both occupational and non-
occupational groups. For a 168-hour week, those exposed as a result of their
occupations were permitted 100 pCi/1 for soluble 226Ra; correspondingly, the
general population was allowed 1/30 of this concentration; i.e. 33 pCi/1 for
soluble 226Ra.
The American Standards Association (ASA) would classify wastes into four
classes which are based on MPC and maximum permissible quarterly intake
(MPQI). Their concentrations for both the soluble 226Ra and a solid matrix
with 226Ra are the following: Class A, liquid <_ 3.3 pCi/1 and solid £ 6.7 x
102 pCi/kg; Class B, liquid > 3.3 pCi/1 but <_ 100 pCi/1 and solid > 6.7 x 102
pCi/kg but £ 2 x 104 pCi/kg; Class C, liquid > 100 pCi/1 but <_ 1 Ci/1 and
solid > 2 x 104 pCi/kg but <_ 200 Ci/kg; Class D, liquid > 1 Ci/1 and solid
> 200 Ci/kg. It is notable that radium wastes do not fit the rule-of-thumb
classification. The ASA classification would place any concentration of
radium into some class.
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Preparation of both potable water from groundwater in sections of Iowa
and Illinois and fertilizer from phosphate-rich regions of Florida are prime
examples of the potential for generating ultra-low radium-containing wastes.
These operations produce wastes between the range of nanocuries per liter and
picocuries per liter and would often be Class B or Class C wastes. Even
if concentrated, most would not exceed Class C. More importantly, however,
the natural matrix from which these wastes are generated are originally Class
B Wastes! Therefore, the simple act of pumping deep-well water for irrigation
in some areas of Iowa and Illinois would be considered as releasing a Class B
waste. The radium problem is further confounded by the ubiquitous and vari-
able nature of radium in almost all environmental media. If many of the
wastes in this study can experience a dilution factor of 100 upon their re-
lease to the environment, they would essentially be at background concentra-
tions .
Wastes which are not radioactive are often a combination of organic and
inorganic material. The organic material is catabolized by living organisms
unless man converts it to carbon dioxide and water by combustion. The inor-
ganic material, though also utilized by living organisms, is subject to other
processes such as chemical changes and weathering. When volume is used as a
measurement criteria, such wastes are usually retained in the biosphere even
though many of the original constituents may have been obtained from deep
within the earth. A prime example of such wastes would be those domestic
solid wastes that end up in sanitary landfills. Such wastes are thought of
as "disposed" since they require little or no maintenance and little if any
monitoring is performed unless groundwater is easily contaminated.
However, radioactive wastes, being essentially all inorganic, are
never thought to be "disposed" of under equivalent conditions because of
their radioactivity. Factors which necessitate a different philosophy when
dealing with radioactive wastes include the following: (1) the "life times"
during which they can exert their deleterious effects are a function only of
time, (2) the "life times" are incapable of being modified (except by artifi-
cially induced transmutation), (3) the long "life time" of many of the radio-
nuclides, (4) the ever-changing chemical states resulting from natural trans-
mutations or decay, (5) the possible change of physical state, as for example
in solid 226Ra. to gaseous 222Rn, and (6) the biological effects. For these
reasons radioactive wastes necessitate long-term protection over and above
that normally used for organic and other wastes.
Concentration and confinement of ultra-low level effluents are desirable
if there were no considerations other than safety. This would be true dis-
posal. Disposal is the best means for ensuring long-term protection since by
definition it is not only for an effective infinite time but also provides
for no interaction with the biosphere. Disposal requires neither maintenance
nor legal controls once accomplished; it is strategy, not a tactic. An ideal
disposal method would be by returning the radioactive matrix to the general
area from which it was obtained; this is especially true if the radioactive
waste matrix is chemically similar to the original matrix. Returning a back-
wash to an aquifer (possibly the original one) is such an example.
-------
As would be expected, the lower the activity level of wastes, usually the
more there is of it. The expense of concentrating large volumes of material
can quickly become excessive and the cost-benefit equation begins to be out
of balance.
The second alternative for ultra-low level waste is delay for decay. In
general these are surface facilities such as evaporation lagoons. When the
radioactive waste has a short half-life this is an excellent solution. For
radium, the expected lifetime of such facilites is insignificant in com-
parison to that of the radionuclide. Ultra low-level effluents released from
storage facilities to the uncontrolled portion of the biosphere may, through
fundamental natural processes of redistribution and transformation, be physi-
cally or biologically accumulated to undesirable levels in the environment.
Delay for decay will usually imply some type of environmental monitoring and
this expense must be factored into the cost-benefit equation.
Dilution and dispersion of ultra low-level radium wastes into either the
aquatic or terrestrial environment must remain an alternative. Radium is
rather widespread in nature,and many of man's endeavors, such as the nuclear
fuel cycle, release radium. When the diluted waste will not make a signifi-
cant impact on the environmental concentration or the ultimate consequence of
an elevated environmental concentration is expected to be insignificant, then
the cost (risk) - benefit equation would suggest using this least expensive
procedure. Of course, if these radioactive substances are to remain in the
biosphere in diluted form, their transport pathways and biological effects
should be well understood.
The aforementioned discussion points out the dilemma of radium-containing
ultra low-level wastes generated from potable water treatment facilities. The
best solution from a radiological health point of view is concentration and
containment, however, the expense involved for a water treatment facility will
likely be inordinate in comparison to the value of the product.
Delay for decay will probably not be acceptable from either cost consid-
eration or protection. The radium half-life is too long, the potential for
eventual release in a rather concentrated form is high. Monitoring will be
required.
Dilution and dispersion may be the only alternative that has a small
enough economic impact to be considered. However, the radiological health
implications will have to be seriously examined. Some important factors are
(1) the natural or background concentrations of radium in the dispersing
medium, (2) the assimilative capacity and volume of the dispersing medium, (3)
the immediate utilization of the dispersing medium, (4) the potential for
reconcentration, transport or other environmental changes, and (5) the future
use of the dispersing media or other locations where the waste may eventually
reside. Potential for transport to man is the key issue. The variables are
almost too numerous to list but include aspects of geography, geology, land
use, hydrology, etc.
One can conclude that a "best" solution to the waste problem generated
by water treatment plants handling radium bearing wastes does not exist. The
10
-------
solution for each plant may lie in an environmental analysis where the com-
plete benefit versus costs (risk) balance is evaluated. This should include
an analysis of alternatives to the use of the ground-water.
Bottled water for consumption is one alternative. Surface waters re-
sources should be examined. It should be pointed out that surface waters
have a great potential for contamination by other man-made or natural hazards,
some of which are as relatively carcinogenic as the radium concentrations
considered in this report. The final analysis should consider all these
aspects.
11
-------
SECTION V
PROCEDURE AND COST BASES
ASSUMPTIONS AND PARAMETERS
Source of Data
Although it has been known for many years that several geographical
areas of the United States have levels of radium in their raw and finished
water supplies which exceed the 1962 USPHS limit for 226Ra of 3.0 pCi/1,
there is relatively little information in the literature about radium removal
or reduction in potable-water supplies. In 1974 and 1975 the Environmental
Protection Agency funded two research projects in order to determine radium-
removal efficiences in water treatment processes. One project was conducted
by the Iowa Department of Environmental Quality11, and the other by the
Illinois Environmental Protection Agency12. These projects studied the
removal efficiencies of lime-soda softening, Ion-exchange, reverse osmosis
and iron removal in an attempt to determine typical removal efficiencies for
these processes. The removal efficiencies, radium-removal models, and waste
stream radium concentrations assumed or calculated in this report were based
largely on a compilation and analysis of data presented in the two afore-
mentioned reports, along with supplemental data from the literature.
Data collected by state agencies on radium levels in Florida waters, as
well as radium removal in several Florida water treatment plants, have also
been included where applicable.
Assumed Radium Level in Finished Water
In order to arrive at specific treatment costs it was necessary to assume
the level of radium which would remain in the finished water. This report
assumes that level to be equal to proposed interim standard for 226Ra plus
Ra of 5 pCi/1. It is recognized that many municipalities may set stricter
standards for themselves and design their processes to reduce radium levels
well below this limit. To do so will increase the costs of treatment above
the costs reported in this report. In some cases, the operation of a plant
will not be effective from a chemical water quality point of view unless a
minimum removal of total hardness is effected by the process. This minimum
total hardness removal may effect removal of radium to levels in the finished
water below the proposed interim standard of 5.0pCi/1. When radium is removed
in the finished water below the limit of 5.0 pCi/1 due to operationally required
minimum hardness removals, the reported treatment costs are for the resulting
lower radium level and not the 5.0 pCi/1 level.
12
-------
All radium removal data reported, analyzed and modeled in this report are
based on measurements of the isotope 226Ra. It is assumed in this report that
the chemical behavior of 228Ra will follow closely the observed behavior of
226Ra in water treatment processes. Municipal water treatment plants (pro-
posed or in operation) must determine the total radium level (22SRa plus 228R4>
and enter the design curves in this report for the total activity (pCi/1)
observed. This procedure will ensure that the proposed interim standard will
be satisfied.
Raw Water Quality Parameters
It was necessary to assume certain raw water quality parameters in order
to calculate treatment costs. Table 2 contains the assumed values of three
typical raw waters which represent the best compromise effectively spanning
the range of water qualities found in the literature for waters in Iowa,
Illinois, and Florida. The total dissolved solids range from a high of 2,000
mg/1 to a low of 400 mg/1. The primary operational variable will be total
hardness. Here the high, medium, and low levels will be 750, 300»and 150 mg/1
as CaC03, respectively.
TABLE 2. RAW WATER QUALITY CONCENTRATIONS ASSUMED FOR CALCULATIONS
High Level Solids mg/1 as CaC03 mg/1 as Ion
TDS 2000
TH 750
Ca++ 500 20C
Mg++ 250 60
ALK 300 360
Medium Level Solids
TDS 1000
TH 300
Ca** 200 80
Mg++ 100 24
ALK 200 244
Low Level Solids
TDS 400
TH 150
Ca++ 100 40
Mg^- 50 12
ALK 100 122
13
-------
TABLE 3. CORRELATION OF RAW WATER QUALITY PARAMETERS WITH RADIUM
DCI, IL
Peru , IL
Herscher, IL
Elgin, IL
Lynwood, IL
Greenfield, IA
Adair , IA
Stuart, IA
Eldon, IA
Estherville, IA
Grinnel, IA
Holstein, IA
Webster City, IA
West Des Moines, IA
Sarasota, FL
Venice, FL
Englewood, FL
Mean
r*
ra = 0.05**
K.»6-
3.26
5.82
14.3
5.55
14.7
14.0
6.30
16.0
50.0
5.2
6.2
14.0
7.1
9.6
4.30
8.73
1.69
11.0
— — — —
THb
286
298
404
246
849
630
710
640
400
915
368
920
530
376
460
570
360
527
0.057
0.606
Cab
153
188
226
142
620
400
450
375
246
600
205
600
275
210
__ _
335
0.036
0.532
Mgb
133
110
178
104
229
230
260
265
154
315
163
320
255
166
_._
206
0.048
0.532
FeC
0.44
0.44
0.12
0.04
0.60
1.6
0.58
0.94
1.9
1.6
1.1
1.8
0.69
0.36
0.87
0.518
0.532
TDSC
1220
890
1426
350
1766
2160
1905
1770
1228
1350
784
1510
1010
1200
1327
0.176
0.532
ALKb
286
318
259
303
215
190
158
182
252
367
298
288
294
260
262
0.252
0.532
Bac
0.13
0.13
0.10
8.7
0.09
<0.10
<0.10
<0.10
<0.10
<0.10
<0.10
<0.10
<0.10
<0.10
1.80
0.335
0.878
Bxc
1.1
0.63
1.4
0.23
1.2
0.91
0.628
0.878
Correlation coefficient for bivariate linear regression of 226Ra with associated chemical parameter
**Correlation coefficient for significance at a = 0.05 level
* pCi/1
b mg/1 CaC03
c mg/1
-------
Raw Water Radium and Water Quality
The raw water data available have been analyzed with respect to a
possible correlation between raw water quality parameters and raw water
radium concentration. Table 3 contains a compilation of raw water data
identified by location. A bivariate linear regression analysis of the data
demonstrates that no significant correlation exists between raw water radium
and any other raw water quality parameter tested at the 95 percent confidence
level. A trend toward significance is noted for the presence of the heavy
metals }iron, barium, and boron along with radium. This trend is not suffi-
ciently useful to predict the concentration of raw water radium and thus it
will be assumed that the radium concentration in raw waters is a random vari-
able with respect to all other raw water quality parameters.
Required Removal Fraction for Radium
Since the limit in the finished water is set and the concentration in the
raw water is a random variable with respect to water quality, the required
removal fraction for radium is a direct function of the raw water radium
content. This can be expressed by the following equation:
f = 1 - (5/RWR) (Eq. 1)
where f = radium removal fraction required and RWR = raw water radium concen-
tration. Figure 1 is a graphical representation of this equation.
Population Ranges Studied
Treatment costs are reported according to the population served by the
water system. Table 4 shows the population range investigated for each
treatment process and the hydraulic flow range assuming a per capita water
consumption of 150 gallons per capita per day (gpcd), or 0.568 cubic meters
per capita per day.
TABLE 4. POPULATION AND FLOW RANGE INVESTIGATED
Population Range Flow Range
Cubic Meters/Day
Lime-Soda Softening 2000 - 1,000,000 1140 - 568,000
Ion Exchange 100 - 50,000 56.8 - 28,400
Reverse Osmosis 100 - 50,000 56.8 - 28,400
COST DETERMINATION
General
Costs reported here have been developed from published data, information
15
-------
60
50
o
Q.
s-
O)
40
1 30
O)
_i
E
20
10
,20
.40
.60
.80
.100
Fraction of Radium Removal Required
to Meet Limit of 5 pCi/1
FIGURE 1. REQUIRED REMOVAL FRACTION FOR RADIUM
16
-------
obtained from equipment manufacturers and suppliers, and data obtained from
actual construction costs of existing plants.
The costs developed in this report are intended as a guide in the devel-
opment of planning estimates only and not in the preparation of bid documents
or detailed cost estimates. Exact capital and operating costs are highly
variable from location to location within the United States, even for plants
of the same size and design. Variables such as local costs of land, materials,
and labor; state or regional differences in building codes; availability of
and existing facilities suitable for modification may accentuate the differ-
ences in treatment costs for similar plants.
The cost data, along with sample calculations which appear in the appen-
dix, are of sufficient flexibility to enable the planner to make adjustments
to the reported costs, when local information is available. For example,
operation and maintenance cost curves can be reduced if the locally delivered
cost of chemicals is less than the assumed cost upon which the estimates are
based. In addition, cost indices are used to provide a baseline for project-
ing costs, and for estimating escalation due to inflation. The indices used
in this report are national indices, readily available to the user. These
indices are often available for major U.S. cities or on a regional basis and
these local or regional indices may be substituted, if desired.
Basis of Cost Estimates
(1) The cost indices used in this report are:
a. Engineering News-Record-Building Cost Index (ENR BCI). This index
was introduced in 1938 in order to measure the effects of wage and
materials price trends. The Building Cost Index has skilled labor
and materials components and is used for cost estimates for buildings,
site development, utilities, and general civil construction. The
national average ENR BCI appears weekly in the "Scoreboard" section
of Engineering News-Record Magazine. City-by-city Building Cost
Indices for 22 U.S. cities appear monthly in the second ENR issue of
the month. The ENR BCI used in the report for all appropriate
curves unless otherwise noted is 1351 for October, 1975.
b. Bureau of Labor Statistics - Labor Costs Index. The index used in
this report is for personnel in Standard Industrial Category (SIC)
494.7, or Water, Steam and Sanitary Systems Non-Supervisory workers.
The base BLS Labor Cost Index for October 1975 is 5.02, the index
has been modified to 7.28 to include overhead and payroll expense
(30% overhead, 15% payroll expense). This information can be ob-
tained from Employment and Earnings Statistics on the Labor Force,
published monthly by the U.S. Department of Labor, Bureau of Labor
Statistics.
c. U.S. Bureau of Labor Statistics - Chemical Index. The index used in
this report to indicate chemical price trends is 209, which is the
October, 1975 Industrial Chemicals (Index; Code 061). This informa-
tion can be obtained from the Wholesale Prices and Price Indexes
17
-------
Data, published monthly by the U.S. Department of Labor, Bureau of
Labor Statistics.
(2) Chemical costs used in this report are reported in Table 5.
TABLE 5. CHEMICAL PRICES USED IN CALCULATIONS
Chemical Price Per Ton Source
Soda Ash (Na_C00) $87,00 February 19, 1976
57% as Na202 3 ENR
Lime (CaO) 48.00 Delivered at Gainesville, FL
(Quicklime) 96% Average of two suppliers 2/76
Salt (NaCl) 40.00 Delivered at Gainesville, FL
(Rock Salt) 99% Average of two suppliers
(3) Costs reported as capital Costs include:
a. Construction for Site Preparation including—
Grubbing, Cleaning, Grading
Roads
Fences and Gates
Utilities
Service Buildings
Design and Specifications
Construction Supervision
b. Plant Construction including—
Piping and Controls
Civil Construction
Mechanical Equipment
Design and Specifications
Construction Overhead
c. Land Costs - assumed to be $750/hectare ($1850/acre)
d. Interest During Construction at 8 percent per annum
e. Start Up Costs - 1/12 or 1/6 of annual operating costs, depending on
plant size.
f. Owners General Expense - 12 percent of total construction costs
(a + b), 9 percent for large plants.
g. Working Capital, 1/16 or 1/12 of annual operating costs, depending on
plant size.
18
-------
(4) Costs reported as Operating and Maintenance Costs Include:
a. Chemical Costs
b. Labor
c. Operation and Maintenance Costs, such as utilities, annual replace-
ment of expendable items, etc.
(5) Total annual costs are based on amortization at 8 percent compound
interest for depreciating capital, 8 percent simple interest for non-
depreciating costs, unless otherwise specified. The useful life of
lime-soda plants was assumed to be 40 years, 20 years for ion exchange
and reverse osmosis.
The major source and method of determining treatment plant costs were
derived from "Monograph for Determining Costs of Removing Specific Contami-
nants from Water," prepared for the EPA by David Volkert and Assoc.13 Sample
calculations for each of the three treatment processes are shown in the appen-
dix.
It should be noted that the cost curves for radium removal derived in
this report are costs associated with construction and installation of entire-
ly new treatment facilities. It has been assumed for the purposes of this
report that the only existing water supply facilities are:
(1) Developed raw water source such as a deep well field, infiltration
gallery, impounded surface supply, etc., and
(2) Water transmission and distribution system.
Many municipalities or water supply utilities in areas where radium
levels exceed the interim standard have treatment facilities which, with pro-
cess modifications, or construction of additional facilities, can be upgraded
to deliver finished water meeting the radium standard at substantially less
cost than that presented in this report.
The real cost of treatment facilities associated only with removal of
radium to acceptable levels can span the continuum between the utility whose
existing facilities already meet the radium standard to the utility which
presently distributes .chlorinated raw water and must construct entirely new
treatment facilities.
An illustrative example of estimating costs associated with upgrading
existing facilities for increased radium removal is shown in Appendix E.
19
-------
SECTION VI
LIME-SODA SOFTENING
GENERAL
The hardness of almost all water supplies is caused by the presence in
solution of calcium and magnesium ions. Other divalent ions such as stron-
tium, ferrous iron and manganese may contribute to the hardness to a much
lesser degree.1"4 The lime-soda process is a precipitative softening process
which uses the addition of lime (CaO-quicklime, or Ca(OH)2-slaked or hydra-
ted lime) to convert the soluble bicarbonates of calcium and magnesium into
insoluble calcium carbonate and magnesium hydroxide. This is the removal
of "carbonate hardness", or the calcium and magnesium ions associated in
solution with the bicarbonate ion. Calcium and magnesium associated with
the sulfate, chloride or other ions, ("non-carbonate hardness"), are re-
moved by the addition of both lime and soda ash (Na2C03) which provides the
carbonate ion necessary for formation of calcium carbonate. Since magnesium
removal occurs only above a pH of about 11 at normal water temperatures,
excess lime sufficient to raise the pH to -11 must be added prior to re-
moval of magnesium as magnesium hydroxide.
The precipitated compounds are flocculated, settled, and removed as
sludge while the clarified effluent is usually filtered in order to polish
the effluent by removing residual floe particles.
The chemistry of water softening is probably best explained or illus-
trated by showing the chemical reactions that take place when lime and
soda ash are added to water containing calcium and magnesium salts. The
reactions in the lime-soda process, then are: 14
C02 + Ca(OH)2 = CaC034- + H20 (1)
Ca(HC03)2 + Ca(OH)2 = 2CaC03i + 2H,,0 (2)
Mg(HC03)2 + Ca(OH)2 = CaCO^ + MgCOg + 2H20 (3)
MgC03 + Ca(OH)2 = CaC03+ + Mg(OH)2+ (4)
2NaHC03 + Ca(OH)2 = CaC034- + Na2C03 + 2H20 (5)
+ Ca(OH)2 = Mg(OH)24- + CaSO^ (6)
+ Na2C03 = CaC03l + Na2SOtf (7)
20
-------
These equations show all of the reactions taking place in softening a
water containing both carbonate and noncarbonate hardness by the lime-soda
process. It should be noted that, in Equation 1, the carbon dioxide is not
hardness as such, but in proportion to its content in the water will consume
lime and must therefore be considered in calculating the amount of lime re-
quired. Similarly, in Equation 5, the sodium bicarbonate or sodium alka-
linity, if present, is not part of the hardness but, since it is included in
the total alkalinity, it will consume lime. Equations 2 and 4 show the re-
moval of carbonate hardness by lime. Whereas only one molecule of lime is
required for one molecule of calcium bicarbonate, Equation 2, two molecules
of lime are required for the removal of one molecule of magnesium bicarbonate,
Equations 3 and 4. Equation 6 shows the removal of magnesium noncarbonate
hardness, shown as magnesium sulfate, by lime. No softening is effected by
this reaction because, for each molecule of magnesium noncarbonate hardness
removed, an equivalent amount of calcium noncarbonate hardness is formed.
Equation 7 shows the removal of calcium noncarbonate hardness, shown as
calcium sulfate, either originally in the water or formed as shown in
Equation 6.
From these reactions it is apparent that the amounts of lime and soda
ash required to soften a water may be calculated from the concentrations of
free carbon dioxide, bicarbonate (usually the total alkalinity), magnesium
hardness, and noncarbonate hardness.15
Figure 2 shows a diagram of the two typical types of lime-soda softening
plants. In the horizontal flow plant of Figure 2a, chemical mixing, floc-
culation, and sedimentation are usually carried out in separate basins as
separate unit operations. Upflow OF' solids contact units, shown in Figure
2b, combine the three above-mentioned processes in one physical unit. Upflow
clarification is less expensive due to the obvious reduction in the number
of process units and smaller area required for plant layout; however,
horizontal flow units provide more positive control of the overall process
and are better able to absorb peaks in plant loading by allowing greater
detention time in the plant.
RADIUM REMOVAL IN THE LIME-SODA PROCESS
Soluble radium, a divalent alkaline earth metal ion similar to calcium
and magnesium is also removed in the lime-soda softening process. Table 6
shows the radium and total removal hardness efficiencies of six lime-soda
softening plants in the United States. The data from Iowa and Illinois are
the most reliable, in that radium and hardness analyses were performed on
water samples taken at the same time. The hardness data from Florida, on
the other hand, were reconstructed from plant operating records on the same
day that the radium samples were taken by another agency. This means that
the two samples may have been taken as much as eight hours apart. It can
be seen from Table 6 that radium removal varied from plant to plant and
ranged from 59-96 percent removal, averaging 80 percent. Figure 3 shows a
plot of total hardness removal versus radium removal based on the data pre-
sented inTable 6. If the two points from Florida plants are discounted, the
line y = x2-86 fits the data reasonably well and serves as the basis for a
radium removal model in lime-soda plants.
21
-------
FIGURE 2a. HORIZONTAL FLOW PLANT
LIME AND/OR
SODA ASH
cn
RAW WATER
INFLUENT
RAPI D MIX
WATER LINE
BACKWASH
WATER WITH
FINE SOLIDS
FLOCCULATION TANK
RAPID
SAND FILTER
SLUDGE
(a) 4% DRY
SOLIDS BY
WEIGHT
WATER
1% Of TOTAL
FLOW BY VOLUME
EFFLUENT
TO CLEAR
WELL
FIGURE 2. DIAGRAM OF TYPICAL LIME-SODA TREATMENT PLANT
-------
FIGURE 2b. SOLIDS CONTACT OR UPFLOW PLANT
DRIVE
Effluent to
Rapid Sand
Filters
SECONDARY MIXING
AND REACTION ZONE
PRIMARY MIXING AND REACTION ZONE
RAW WATER
SLURRY POOL INDICATED BY SHADED AREAS
BLOW-OFF AND DRAIN
-------
1.00
.80
o
4->
O
.60
03
>
o
O)
CO 4Q
cu • ^u
c
(O
-l->
o
.20
x =
+-
0 =
Q-
#-
West DesMoines, 1A
Webster City, 1A W/0 Soda Ash
Webster City, 1A W Soda Ash
Peru, 111 (3 dates)
Elgin, 111 (3 dates)
Englewood, Fl
Venice, Fl
,20
.40 .60 .80
Radium Removal Fraction
1.00
FIGURE 3. LIME SODA PROCESS, TOTAL HARDNESS REMOVAL FRACTION VS
RADIUM REMOVAL FRACTION.
24
-------
TABLE 6. RADIUM226 AND TOTAL HARDNESS REMOVAL EFFICIENCIES LIME-SODA SOFTENING
MKIATION
W. Di/n HiilncH, IA
8/1/7/1
WclmtiT filly, IA.
r;l;ir If I.T //I
8/1 J/7/i
Wfl.Mlcr filly, IA
8/13/7/,
Wi-hslcr f.'lly, IA
ChiririiT ll\
2/20//5
Wi'hnl IT fll 1 y, IA
ci.iriiiiT in
2/20//5
IV.-II, II,
2/20/75
r,.in, II,
,'/25//5
I'crn, II, I//I//5
Mf.-in
Klr, In, II. 3/7/75
Klr,ln, II, 3/1/1/75
Kip, In, II. 3/21/75
Mi-.-iu
Vrnli c, Kl, R/7/75
K.np, 1 runnel, Kl.
H///75
CI-ARIKIKKS
Kn In
1'CI /I
9. 1
6. 1
h. I
7.H
7.8
6 . /i 9
5./i'l
5. /ill
5.82
7 . /i 5
5.7
3 . 5 1
5.55
8.73
1 . 69
Ra mil.
pCl/l
2.6
1 .9
2.6
0.9
0.3
7, RA
Ki'imiwi 1
72
69
57
88
96
Til In
mi:/] <;.-i<:<>3
376
507
507
/i82
/.H2
32'l
278
286
289
2'ifi
2/i 3
242
2/,/i
570
360
Til Dul
mp/1 C.iCO
215
1 ) 1
282
150
1 50
"/„ Til
RKM
/i 3
34
V,
69
69
pll Trr.-il -
m t , 1 1 1
1 0 . /i
10.05
10.1
10.95
10.95
8. /i
H./i
B./i
10.2
10.2
1.0.2
'). 7
8.5
FI 1,'IF.KS
RA In
|>CI/ 1
2.6
1 .9
2.6
0.9
0. 3
KA Out
l'CI/1
2. 15
0. 9
0.9
.J.'J
0. i
0.5!
1 .62
1 .33
1.15
.75
.80
. 71
. 75
2.19
.69
"/.. Hn
Prninv.-i 1
10
53
65
67
n
Til In
mr./KI.KIMj
21 5
3 n
282
I r,0
1 50
Til Dul
m p. /I C.-iCd.
190
262
262
106
106
J 7/1
180
122
l/i7
99
1 12
95
102
100
166
-/. Til
II W
12
21
1
29
29
dVKRAKI,
7. R.i
K KM
75
85
85
96
96
92
70
76
79
90
86
80
85
75
59
"/, Til
H KM
/i 9
/i 8
/,8
78
78
/i 7
35
57
/i 9
60
5/j
61
59
82
5/i
-------
The data experience considerable scatter; however, a reasonable model
for the lime-soda process is given in Equation 2:
Total Hardness Removal Fraction = (f)2-86 (Eq. 2)
It is obvious that many plants will not operate at total hardness re-
movals much below 45 percent. A lower limit of 35 percent total hardness
removal has been chosen. This limitation places a lower limit upon the
radium removal fraction of 69 percent.
REQUIRED TOTAL HARDNESS REMOVAL
The project will consider raw water radium concentrations from 7.5 to
50 pCi/1. By substitution of Equation 1 into Equation 2, the total hardness
removal can be expressed as a function of the raw water radium concentration.
Total Hardness Removal Fraction = [1 - (5/RWR]2'86 (Eq. 3)
This function is graphically presented in Figure 4.
Because of the 35 percent lower limit on total hardness removal all the
waters containing 16 pCi/1 or less of radium will receive a 69 percent radium
removal. Figure 5 shows the finished water radium concentrations for the
lime-soda process as a function of raw water radium concentration.
Figure 6 is a plot of radium removal efficiency versus pH from plant
data. This plot was made in order to determine if radium removal was depen-
dent on pH of treatment. This figure shows a clear trend toward higher
radium removal efficiencies as increased pH. The number of data points is
insufficient to establish the statistical significance of this relationship
and so it is presented here for illustrative purposes. It is, of course,
generally true that total hardness removal increases with pH in the lime-
soda process. The adjustment of the pH over and above that normally used in
hardness removal is not considered to be a viable operational parameter to
effect increased radium removal.
WASTE STREAMS
There are two effluents to be considered: lime sludge and backwash
waters. The lime sludge is a combination of the chemicals used, hardness
removed, and other contaminants, such as radium, that will settle within the
time frame of the clarifier design. The clarified overflow then goes to a
sand filter to remove those particles and materials that were not removed
in the sedimentation unit. Periodically the sand filter must be backwashed
to clean and remove these carry-over particles.
The sludge solids are principally CaC03 and Mg(OH)2 with varying amounts
of other cations, clay, sand, and other trace metal contaminants such as
26
-------
c
o
o
-------
5.00
o
o
0.00
4-
_L
j
16.00
26.00 36.00
Raw Water Radium, pCi/1
46.00
56.00
FINISHED WATER RADIUM CONCENTRATION VERSUS RAW WATER RADIUM CONCENTRATION FOR
I.TMF-SnDA SnFTFNTNG
-------
1.00
0.80
o 0.60
ra
rO
>
O
E
ZJ
0.40 ,_
0.20
X=
0=
Q] =
West DesMonies, la
Webster City, 1A W/0 Soda Ash
Webster City, 1A W Soda Ash
Peru, 111
'.= Englewood, Fl
1= Venice, Fl
J I
8.0 9.0 10.0 11.0
pH of Treatment
FIGURE 6. RADIUM REMOVAL FRACTION VS pH OF TREATMENT, LIME SODA PROCESS.
-------
radium. The exact characteristics depend upon the raw water quality. In this
report the settled sludge will be assumed to be 4 percent solids. The amount
of sludge produced per day is a direct function of the total hardness re-
moved and the plant capacity. Radium concentration in the sludge will depend
upon the total hardness removed as well as the raw water radium concentra-
tion. The best available data11 indicate that about 97 percent of the radium
removed by the plant will appear in the lime sludge.
Backwash water is normally settled and the supernatant recirculated to
the head of the plant and its quality will be degraded by the fine particles
accumulated on the filter since the previous washing. These fine particles
will normally be on the order of 3 percent of the lime sludge production.
The best available data11 indicate that about 2 percent of the finished
water flow is used for backwash purposes:
Backwash flow, gal/day = (0.02) (150) (Pop.) = 3 (Pop.) (Eq. 4)
Normally a holding tank is provided to achieve some sedimentation prior to
discharge. Radium concentration in the backwash is considered to be about 3
percent of the radium removed by the plant. Newer plants have recirculated the
holding tank effluent to the head end of the plant whereas older plants
primarily discharge the backwash to a sanitary sewer.
Lime Sludge Production
The production of lime sludge in terms of dry sludge per million gallons
of plant capacity is primarily a function of the total dissolved solids and
the total hardness removal fraction.
Table 7 shows the pounds of dry sludge per million gallons produced at
the various input conditions. The sludge production is based upon a factor
of 3.5 pounds of dry sludge produced per pound of hardness removed as calcium
carbonate. The theoretical sludge production would be 2.0 pounds of dry
sludge produced per pound of hardness removed. The difference is due to
water of hydration in the calcium carbonate and magnesium hydroxide sludge
matrix which cannot be removed by dewatering or heating to 105°C. The factor
3.5 pounds of dry sludge per pound of hardness removed is based upon exten-
sive experimental work by Burgess and Niple, Ltd. on lime-soda softening
sludges in the state of Ohio1". The sludge production versus total hardness
removal is graphed in Figure 7. Analysis of the curve indicates the expres-
sions:
Dry Sludge Production = 21,900 (Total Hardness Removal at
2000 mg/1 TDS) (Eq. 5)
or
Dry Sludge Production = 8760 (Total Hardness Removal Fraction at
1000 mg/1 TDS) (E(l- 6)
30
-------
O
=tt=
OJ
cn
cu
18000.0
16200.0
14400.0
12600.0
10800.0
9000.0
7200.0
5400.0
3600.0
1800.0
0.0
0.0 0.1
I
0.9
1.0
0.2 0.3 0.4 0.5 0.6 0.7 0.8
Total Hardness Removal Fraction
FIGURE 7. LIME SLUDGE PRODUCTION VERSUS HARDNESS REMOVAL FOR VARIOUS TOTAL DISSOLVED SOLIDS
-------
or
Dry Sludge Production = 4400 (Total Hardness Removal Fraction
at 400 mg/1 IDS)
where the dry sludge production is in pounds per million gallons.
(Eq. 7)
This report will assume that the lime sludge will exit these sedimenta-
tion units at 4 percent solids. Therefore, the wet sludge production rate
will be 25 times greater than the dry production rate (DSP) . Since 9 per-
cent of the radium removed by the plant will be contained in the lime
sludge, it is possible to predict the radium concentration as follows:
Radium Concentration,
Wet Lime Sludge,
Picocuries/Kg
For RWR >16 pCi/1 and
Radium Concentration,
Wet Lime Sludge
Picocuries/Kg
= ,1.42 x 10-
RWR - 5
Dry Sludge
Production, Ib/MG
(Eq. 8)
= 1.01 x 10-
RWR
Dry Sludge
Production, Ib/MG
(Eq. 9)
For RWR <16 pCi/1.
TABLE 7. LIME-SODA SLUDGE CALCULATIONS
Solids
TDS, Mg/1
2000
2000
2000
1000
1000
1000
400
400
400
RWR
pCi/1
7.5
20
50
7.5
20
50
7.5
20
50
Ra Removal
%
69
75
90
69
75
90
69
75
90
THR
%
35
44
74
35
44
75
35
44
75
Amt. TH
Mg/1 as CaC03
262
330
555
105
132
222
52
66
111
Dry wt. sludge
Ib/MG
7648
9633
16200
3065
3853
6480
1518
1927
3240
However, the total hardness removal is not allowed to fall under 35 percent
even at low raw water radium concentration. Therefore, the dry sludge pro-
duction is a constant for each of the three water qualities for all RWR's less
32
-------
than 16 pCi/1. Typical values for radium concentration are shown in Table
8 as calculated for the plants with the indicated size at various RWR and
TDS values. As one would expect, the concentration of removed radium in-
creases as the TDS decreases, but remains constant with changes in population
for a given raw water radium concentration. The highest radium concentration
in the table is associated with 50 pCi/1 RWR and a low TDS of 400 mg/1. The
value here is about 4,500 pCi/kg wet weight. If this sludge is dewatered to
a "dry" state of about 70 percent solids, the concentration would increase to
about 78,880 pCi/kg. Normal surface soils may average some 700 pCi/kg. Dis-
posal methods must therefore look to either containment or dilution with soil
or other material such as municipal solid waste, at a volume ratio of approxi-
mately 100 to 1. At the lower raw water radium concentration of about 16
pCi/1 and high TDS (2000 mg/1) the radium concentration in the sludge drops
by an order of magnitude. The "soil" dilution necessary to reduce the con-
centration to "background" levels is then lowered to a 10 to 1 ratio.
TABLE 8. TYPICAL VALUES OF LIME SLUDGE PRODUCTION
AND RADIUM CONCENTRATION
Parameters
RWR
pCi/1
50
16
50
16
50
16
50
16
50
16
50
16
TDS mg/1
2000
2000
2000
2000
1000
1000
1000
1000
400
400
400
400
Pop. millions
1.0
1.0
0.02
0.02
1.0
1.0
0.02
0.02
1.0
1.0
0.02
0.02
Prod, of Wet
Sludge Ib/day
6.08 x 107
2.87 x 107
1.22 x 106
5.74 x 105
2.43 x 107
1.15 x 107
4.86 x 10 5
2.30 x 105
1.22 x 107
5.69 x 106
2.43 x 105
1.14 x 105
Concentration
pCi/kg wet
8.96 x 102
4.65 x 102
8.96 x 102
4.65 x 102
2.24 x 103
1.16 x 102
2.24 x 103
1.16 x 103
4.48 x 103
2.35 x 10 3
4.48 x 103
2.35 x 103
Backwash Production
The settling tank effluent in a horizontal flow tank or the unit
effluent in a solids contact or upflow plant is routed to a rapid sand
filter. These filters remove fine particles that did not settle in the
previous unit. Filters are normally backwashed once each 24 hours to re-
move the accumulated material. Generally, about 2 percent of the total water
softened is used for this purpose. Under normal conditions, backwash water
is extremely dilute, but the solids concentration can be appreciable at
times when processes preceding filtration are not functioning properly11.
Under normal conditions when radium contamination is not a probljem,
33
-------
backwash water should be held briefly for rough settling and recirculated
to the head end of the plant.
The quality of backwash water is generally good if solids are allowed
to settle out. Therefore, if holding facilities are installed, it is practi-
cal to recirculate this effluent through the waterworks rather than dis-
charge it. Several statements indicate a potential problem with this pro-
cedure when radium is a contaminant: "Settling efficiency in the waterworks
can also be expected to improve due to recirculation of calcium carbonate
particles" and "should there be a build-up of fines in the mixed untreated
water." The obvious conclusion is that there is a potential for recircula-
tion of radium also. Radium would be expected to be in an insoluble form
and accompany the fate of the solids. The only facilities required for re-
circulation are a waste holding tank and pumps. Initial investment is low
and maintenance and operating costs are minimal.1
If the raw water radium is greater than 16 pCi/1, the amount of radium
removed per day will be equal to 5 less than the effluent concentration
multiplied by the flow in liters per day. The amount of radium that will
show up in the backwash will be approximately 3 percent of that value. The
best available data on the amount of water used in backwashing the filter in-
dicates that about 2 percent of the flow is used. If these factors are com-
bined, the flow parameters cancel out and the expression follows:
Backwash Radium Concentration, pCi/1 = 1.5 (RWR-5) (Eq. 10)
If the raw water radium is below 16 pCi/1, the expression changes to
that shown in Equation 11;
Backwash Radium Concentration, pCi/1 = 1.035 RWR (Eq. 11)
These two expressions are shown graphically in Figure 8.
METHODS FOR LIME SLUDGE DISPOSAL
Alternatives for disposal of lime sludges are quite numerous and varied.
The feasibility of many alternatives depends upon the population (plant
capacity). Others may be limited by capital cost considerations. The
approach in this report will be to consider the alternative, its practical-
ity, and cost, initially without regard to the radium concentration. Then
at various critical steps and at the end point, the radiological implications
will be considered. Changes in limitations,precautions, or complete aban-
donment of the alternatives can then be addressed.
Several of the more important disposal alternatives are listed below.
I. Discharge
A. Discharge to sanitary sewers
34
-------
100.00
90.00
80.00
S 70.00
Q-
r>
o 60.00
to
4->
§ 50.00
o
o
ra
CO
ra
40.00
30.00
20.00
10.00
0.00
6.00
16.00
26.00 36.00 46.00
Raw Water Radium Concentration, pCi/1
56.00
FIGURE 8. BACKWASH RADIUM CONCENTRATION, WITH LIME-SODA SOFTENING
-------
B. Discharge to local receiving water
C. Wet pumping or trucking to local sanitary landfill
II. Storage
A. Permanent lagooning
B. Sanitary landfill
1) With prior temporary lagooning
2) With prior mechanical dewatering
a) Vacuum filtration
b) Centrifugation
c) Others
C. Other natural or man-made depressions (all with some dewatering
prior to transportation)
1) Strip mine areas
2) Borrow pits and quarries
3) Others
III. Utilization
A. Direct without drying
1) Farmland and pasturelands
B. With Prior Dewatering
1) Farmland and pastureland
2) Road Stabilization
3) Calcination and recycle
IV. Disposal
A. Direct - recharge to aquifers
B. With prior dewatering
1) Salt mines, coal mines, etc.
C. As a nuclear waste
Discharge to Sewers
A report by Burgess and Niple16 has an excellent discussion of discharge
of lime sludge to sanitary sewers. Important points to be considered from a
physical-chemical point of view are as follows:
(1) Pilot plant studies are needed to determine the tolerance of wastewater
treatment processes to lime sludge at a particular facility.
(2) Primary settling tanks are required at the wastewater treatment plant
to prevent lime sludge from being discharged to the secondary treat-
ment processes.
(3) Holding tanks are needed so that lime sludge is discharged from the
water treatment plant at a uniform rate.
(4) Provisions must be made for flushing and cleaning wet wells.
(5) Digester capacity must be provided for the additional sludge and
digester design must include additional mixing and provision for with-
drawing more dense sludge.
36
-------
(6) Lime sludge should not be discharged to installations having Imhoff
tanks or similar units.
Since the sewer flow is on the order of 100 gpcd, the radium concentra-
tion in the sewer when the lime sludge is discharged to a sanitary sewer,
will be nearly equal to the original raw water concentration. However, it is
expected that the form of the radium will now be insoluble and wastewater
treatment plants should remove over 95 percent of this insoluble radium.
These factors lead to two basic conclusions: (1) the effluent of the waste-
water treatment plant will have a radium concentration near that of the
finished product of the water treatment plant regardless of the raw water
radium concentration, and (2) the digested sludge will have a radium con-
centration on the same order of magnitude as the original lime sludge since
the dry weight production of domestic sewage sludge is probably no greater
than 1000 to 2000 Ib/MG. Compare these values to the lime sludge produc-
tion in Table 8.
The fate of the digested sewage sludge would therefore have to be
controlled to the same degree as the original lime sludge. One should con-
clude, therefore, that discharge of lime sludge from a high radium water
treatment facility to a sanitary sewer is not an attractive solution.
Discharge to Watercourse
Discharge of water treatment plant lime sludges into a watercourse has
historically been a widespread practice in the industry. Recent Federal and
State regulations now prohibit the discharge of waste sludges into streams.
With the additional hazard of elevated radium concentrations, this practice
should be discouraged.
Discharge to Sanitary Landfill
Lime sludge mixed with refuse reportedly aids in compaction of refuse
in a landfill15. Some leachant will be produced if the sludge is not first
dewatered to at least 20 percent solids. The behavior of radium under these
conditions is not understood. It may remain insoluble and remain fixed
within the sludge matrix during the early periods of leaching. On the other
hand, its solubility may increase as the pH of the landfill decreases with
age. Burgess and Niple16 suggests that unless the lime sludges are de-
watered, a town could not absorb, without leaching, more than 16 percent
of its lime sludge in the size landfill the town would generate if the
sludge were 4 percent solids.
Permanent Lagoons
A permanent lagoon can be designed for long term storage of lime
sludges. Lagoons of about five to ten feet of depth and about 2.0 acres
per million gallons per day per 100 milligram per liter of hardness removed
are required15. The area is divided into at least six sections. Wet sludge
is added in layers no more than 2 inches thick. This allows drying to about
70 percent solids, before the next layer is applied. Permanent lagoons may
be reclaimed as useful land after the lagoon is filled. It may be paved or
given an earth cover depending upon the expected use. Parking lots,
37
-------
playgrounds, golf courses, industrial parks, and recreational parks are more
suggested uses.
Because of the radon daughter hazard potential, home building on re-
claimed lagoons should be discouraged. Concentrations in the compacted
sludge may approach 105 pCi/kg. Working Level (WL) is a measure of the
alpha emitting radon daughters in an atmosphere. Starting with a "soil"
concentration of 105 pCi/kg 226Ra, one can estimate a working level of 0.2
in homes if they were built over this land.
This would also result in 340 yR/hr or about 3R/year outside over the
land, a value much higher than the average occupationally exposed worker
receives. Concentrations on the order of lO4 pCi/kg can be expected to
occur frequently; this is equivalent to about 0.02 WL or O.SR/year^ a magni-
tude triple the average national radiation background for the United States.
With sludge particle size on the order of 3 to 8 microns, the smaller
particles present a definite potential health hazard to the lung from both
radium and its daughters. Because these particles adhere to each other as
drying proceeds and also because of compaction, the air concentration poten-
tial should be reduced. However, the information necessary to assess this
potential is not known.
If sludges are covered with overburden, shielding from gamma radiation
results in addition to a concomitant reduction in potential airborne parti-
culates of radium or its daughters.
Permanent lagoon design concepts could be used as foundations for
sanitary landfills. This would (1) provide a water barrier and retard
leachate transport, (2) neutralize acid effects, and (3) utilize less land.
This is expecially important for Florida with its high water table and sandy
soil.
Temporary Lagoons
Temporary lagoons may be used for thickening and dewatering a sludge
before transport to another treatment method. Lagoons of 0.7 acres per
million gallons per day per 100 milligrams per liter hardness removed are
required, based on a depth of five feet16. Alternate filling of one of
three sections to about one foot is suggested. With decanting and drying
the section should achieve about 25 to 40 percent solids before the next ap-
plication. Concentrations of 226Ra will be on the order of 103 to 10^
pCi/kg. "Dust" problems should be much less severe than the drier permanent
lagoons. After sufficient build-up and dewatering, the sludge must be trans-
ported to another treatment site; however, the weight has now been signifi-
cantly reduced.
When the percent solids in the sludge exceeds 20, it can be mixed with
the refuse in a sanitary landfill without expecting leachant . Dump trucks
or power spreaders disperse the dewatered sludge during the fill or on top
of the fill just prior to the dressing of the tppsoil.
38
-------
Mechanical Dewatering
Mechanical dewatering can reduce volume and increase solids content.
Vacuum filtration and centrifugation are well known mechanical dewatering
processes. Solids may exceed the 20 percent value with ordinary equipment
and cycle times. Then the sludge would be suitable for mixing with refuse
in a sanitary landfill. 225Ra values would parallel those of the product
from temporary lagoons. The primary disadvantage of the mechanical dewater-
ing processes is its high capital and high operating costs, especially for
small plants.
Application to Man-made Depressions
Burgess and Niple15 have presented an excellent discussion of the
application of lime sludge to strip mine areas. Here the sludge would aid
in the reclamation of the soils and reduce the problem of acid mine drainage.
The acidity, however, may eventually convert the stored radium to a more
soluble form. Large quantities of sludge could be handled in the mined area,
but the distances involved may make transportation costs excessively high.
The costs would have to be weighed against the benefit from the reclaimed
lands or reduction of the problem acid mine drainage. The fate of possible
radium leachates will depend upon the characteristics of the deposits and
the hydrology of the area. Use of reclaimed land would depend greatly upon
the final concentration in the soil cover and the potential for radium uptake
in the cover vegetation or the potential hazard of uptake if it were to
exist. For example, forestry would be more favorable than cropland or
pasture. The difference between the latter two choices may not be evident
without further investigation.
Other man-made depressions should be considered. Abandoned quarries,
for example, limestone or aggregate, may provide excellent storage. De-
watered lime sludges along with other material may provide reclamation of
these areas. Another type of storage would be borrow pits, although volume
and accessibility may be limiting factors.
Application to Farmland
Application of "waste" lime sludges to farmland is a sensitive issue to
some farmers. Application of the same sludges containing measurable quanti-
ties of "radioactive" materials will be an even more sensitive issue.
Burgess and Niple16 present a thorough discussion of the need, value and
disadvantages of the concept of liming farmlands, however, there is no
consideration of the case where the sludge may come from high radium raw
waters. Without regard to radium, the major advantages and disadvantages
are listed below.
Advantages—
(1) Liming of vast area of farmland would be desirable.
(2) Lime sludge has more neutralizing power than marketed lime.
(3) Lime sludge has an excellent size distribution
(4) Lime sludge provides calcium and magnesium, both essential for
plant growth.
39
-------
(5) Liming increases the availability of phosphorus, molybdenum, and
magnesium.
(6) Liming reduces harmful concentrations of aluminum, manganese, and
iron.
(7) Liming increases favorable microbial activity in many soils.
(8) Liming results in better soil structure.
Disadvantages —
(1) Farmer acceptability of the concept is low.
(2) Transportation costs limit radius.
(3) Application methodology needs investigation.
(4) Competition with commercial lime producers.
(5) Application times are limited to certain seasons and to dry soil
conditions.
(6) Other methods must be found to handle excess.
(7) There will certainly be public opposition to use of radium bearing
sludges on farmland.
Farmers in Ohio have purchased 1.87 tons of commercial lime/acre limed/
year.16 Many lands in the same area could utilize 2.7 to 3.5 tons/acre.
Liquid sludge (1 to 6 percent solids) could be spread with tank trucks or
sprayed; thickened sludge (7 to 15 percent solids) may require pressurized
tank trucks; dewatered sludge (20 to 40 percent solids) can be spread by
hopper bed trucks.
Uptake of radium by crops is not well understood. If the soil/sludge
ratio exceeds 100 to 1, then the added concentration in the soil may approach
natural levels of 226Ra in soils. Another consideration would be the future
development of farmlands into homesites. A possible concern here would be
the build-up of radon daughters in structures built over such lands. The
hazard potential would be measured in Working Levels (WL). A home should
not exceed 0.01 WL. Appendix F calculates that the worst possible 1 year
case, assuming no uptake by vegetation or weathering loss, results in
approximately 0.0004 WL. Succeeding years would require less for increasing
pH. Most likely, hundreds of years would be required before WL to farmers
in their homes reached 0.01 WL.
Utilization as Raw Material
If the lime sludge is dewatered and dried to 20 percent or more solids,
other uses could be considered. Several possibilities exist. Dried lime would
provide impervious material to stabilize roads, embankments or other con-
sequences of earth moving. Radium content would be a minor problem in those
uses. Proposals for use in building materials should be carefully considered
in light of the possible release of radon into the environment that the
materials will enclose. Mixing with sewage sludge as a disinfectant and
deodorant may be very acceptable. Utilization as a neutralizing agent for
acid waste would have to be considered in light of the fate of the effluent.
Calcination for reuse should be discouraged whenever high radium concentra-
tions are involved.
40
-------
Disposal
Recharge of deep aquifers with diluted lime sludge was considered.
Recharge wells are extremely expensive. Utilization time of recharge well,
because of rapid loss of porosity, may be very short.
With prior dewatering of sludges, salt mines would provide the safest
method of solving the waste problem. The prevalence of salt mines over
large areas of the U.S. makes this an attractive alternative. Salt mines
are inherently stable with almost no possibility of leaching by ground
waters since any groundwater would have dissolved the salt.
Abandoned mines of other types may be considered. Many problems are
immediately evident. Items such as distance, location, depth, safety,
ownership, future mining, geology, groundwater, etc. are some of the key
words of problems that would have to be addressed.
Treatment of the lime sludge as a nuclear waste was considered. The
process would involve some method of dewatering, drying, solidification
with cement or other material in 55-gal±Dn drums, shipping, and burial in
a controlled site. Cost beyond dewatering, drying and shipping would be
expected to exceed $0.04 per 1000 gallons of finished water.
METHODS FOR BACKWASH DISPOSAL
Alternatives for disposal of filter backwash are less than for
the lime sludges. Some methods will depend upon location, plant capacity
and perational factors. Several of the more important alternatives are
listed below.
I. Discharge
A. Discharge to sanitary sewer
B. Discharge to local receiving water
II. Storage
A. Tanks or lagoons
1) for settling and decanting into receiving water
2) for settling and pumping supernatant back to plant
III. Disposal as a Nuclear Waste.
Discharge to Sewers
If the backwash from the lime-soda process filters is released to
sanitary sewer systems in the same city, the flow will be diluted into the
approximately 100 gallons per person per day of sanitary sewage. Therefore,
the concentration of radium in the sanitary sewer system prior to treatment
would be a function of the radium concentration in the backwash flow. Assume
that no settling tanks are provided. The radium concentration in the back-
wash is a function of the raw water radium concentration (RWR) and whether
it exceeds 16 pCi/1. No specific information has been located on the ability
of a sewage treatment plant (secondary treatment) to remove radium. However,
41
-------
there are strong indications in the literature that non-essential elements
are not removed much greater than 40 percent. This effect is probably more
of an absorptive mechanism rather than an assimilative mechanism of uptake.
In order to be conservative, the 40 percent removal is used as a model,
the equations for the radium concentration in the sewage treatment effluents
become as follows:
Sewage treatment plant effluent, radium concentration, pCi/1 = 0.027
(RWR-5)
for RWR >16 pCi/1 and (Eq. 16)
Sewage treatment plant effluent, radium concentration,pCi/1 = 0.0186
(RWR)
for RWR <16 pCi/1. (Eq. 17)
Equation 16 and 17 are combined graphically on Figure 9.
It is obvious from this analysis that the concentration in the sewage
treatment effluent will be much less than the guideline of 9 pCi/1 discharge
limit. If there are any complications caused by putting the backwash
materials into the sewage treatment plant, these should be considered from a
chemical point of view. The discharge of this effluent to the sewage treat-
ment plant is a viable alternative. The remaining 40 percent of the radium
that enters the sewage treatment plant will, of course, exit the plant via
whatever means of sludge handling and disposal is utilized. In comparison
to the lime-soda sludge, this is not expected to be a serious problem. In
most cases, it will probably go to the same location or another sanitary
landfill.
Discharge to Receiving Water
The second alternative to be considered for release of backwash is to
allow the water to be discharged into a local watercourse. If we assume
that the EPA would apply a guideline similar to that imposed upon the
phosphate industry, a discharge limit of 9 pCi/1 of radium would only allow
plants with influent concentrations of 8.7 pCi/1 or less to use this alter-
native. It would be very important to know the current levels of radium in
the proposed watercourse. If the river contains radium at about the same
magnitude or has the ability to dilute the discharge by an order of magni-
tude, then this may become a viable procedure. It may also be necessary to
make a determination as to whether the river water is used as a drinking
water source somewhere downstream and of impact of releases upon that use.
Table 9 lists some river water radium concentrations in the U.S.A.
The average concentration is about 0.3 pCi/1 with a low of 0.002 and a high
at 3.70 pCi/1. It is obvious that in many cases the backwash from a lime-
soda process will exceed the concentration in the river. Therefore it is
42
-------
1.75
1.50
e
1 1-25
O)
Z3
LU
c
fd
O)
1.00
.75
CD
? .50
.25
.00
I
10
15
20
25 30 35 40
Raw Water Radium pCi/1
45
50
55
60
FIGURE 9. RADIUM IN WASTEWATER PLANT EFFLUENT IF BACKWASH OF LIME-SODA PROCESS IS DISCHARGED
TO SANITARY SEWERS.
-------
TABLE 9. -Ra CONTENT OF SELECTED RIVERS IN THE UNITED STATES
City Supply
Source
Ra Concentration
pCi/liter H20
Raw-
Water
Atlanta, Ga.
Baltimore, Md.
Birmingham, Ala.
Bismarck, ND
Boston, Mass.
Charleston, S.C.
Charleston, W. Va.
Cincinnati, Ohio
Denver, Colo.
Detroit, Mich.
Indianapolis, Ind.
LaVerne, Calif.
Louisville, Ky.
Oklahoma City, Okla.
Omaha, Neb.
Philadelphia, Pa.
Phoenix, Ariz.
Pittsburg, Pa.
Portland, Ore.
Raleigh, N.C.
Richmond, Va.
Sacramento, Calif.
Salt Lake City, Utah
San Francisco, Calif.
St. Louis, Mo.
Tacoma, Wash.
Washington, D.C.
Chattahoochee R.
Gunpowder R.
Cahaba R. and L. Purdy
Missouri R.
Nashua R.
Edisto R.
Elk R.
Ohio R.
South Platte R.
Detroit R.
Fall Cr. and White R.
Colorado R.
Ohio R.
N. Canadian R.
Missouri R.
Delaware R.
Along Verde R.
Allegheny R.
Bull Run R.
Walnut Cr.
James R.
Sacramento R.
Cottonwood Cr.
Calaveras Res.
Mississippi R.
Green R.
Potomac R.
0.017
0.020
0.024
0.243
0.014
Q.181
0.041
0.061
0.077
0.026
0.137
0.100
0.084
0.106
1.770
0.048
0.027
3.700
0.014
0.022
0.033
0.018
0.034
0.018
1.080
0.002
0.033
Hursh C1953)2
44
-------
necessary to consider the river flow required for dilution.
The river water flow required will be based upon reducing the concen-
tration in the receiving water to 5 pCi/1. Using a mass balance and ne-
glecting the concentration in the river, then
River Flow Required, MGD =0.9 (RWR-5) (Pop.) (Eq. 18)
for RWR >16
and
River Flow Required =0.62 (RWR) (Pop.) (Eq. 19)
for RWR <16.
Figure 10 shows these equations graphically and demonstrates that there
should be little difficulty in finding a receiving water with the necessary
dilution.
Holding Tanks, Lagoons and Recycle
The filter backwash flow may be routed to a holding tank or lagoon in
order to settle the solids. Holding tank volume should be slightly greater
than the volume of backwash water used for filter recycle. Holding tanks
are usually about 8' deep. Pump capacity (for discharge or reclamation)
will be on the order of twice the average rate of backwash.
The amount of sedimentation achieved in these tanks and lagoons depends
upon many factors, including surface area, inlet-outlet design, detention
period, agitation, bottom design, and characteristics of the solids.
A large fraction of the solids enter the tank in the first few minutes of
backwash. The behavior of removed radium in the system is not documented.
It is likely that the radium will be fractionated in the same manner as the
suspended solids.
Many plants return the settled backwash to the head end of the plant.
Without consideration of radium solubility effects, a simple mass balance
model would indicate that effluent radium concentrations would initially
increase slightly if more than 2 percent of the removed radium is returned
to the head end of the plant with a backwash flow of 2 percent of the
finished water. The equilibration time is about 5 cycles (or days). The
project has assumed that 3 percent of the removed radium will appear in the
backwash. Therefore, a holding tank need only to settle one-third of the
solids (and radium) in order that recycle will keep the effluent radium :
concentration equal to the design value. No credit was given for the fact:
that the radium returned to the head end via this method may be in an in-
soluble form.
If the holding tank removes more than 33.3 percent of the incoming
solids, the concentration of radium in the finished water or the recycle will
45
-------
100
o
o
o
X
-o
oo
1°
S-
ai
a:
-a
cu
0.1
cr
O)
D;
0.01
100
10
1.0
0.10
O)
TD
0)
i.
CT
-------
theoretically decrease slightly (about 1 percent) and maintain that value
after the first five cycles. It is likely that most holding tanks will
achieve greater than 50 percent removal of suspended solids. The settled ma-
terial will have to be handled in the same manner chosen for the lime sludge.
In a few cases the material in the holding tank may be deliberately
agitated in order to provide a uniform concentration of solids or radium to
discharge into a receiving water. This practice should be weighed against
the advantage of including the holding tank sludge with the treatment method
chosen for the lime sludge.
Treatment as a Nuclear Waste
If the lime sludge of a plant were treated as a nuclear waste as pre-
viously discussed, the backwash could be included in the process for an
additional cost of about 3 to 5 percent of the overall cost. Holding tank
capacity could be expanded to a size necessary to achieve 85 to 95 percent
removal. Coagulation aids would be used. The product sludge would then be
routed to the same processes designed for the lime sludge, i.e. dewatering,
drying, fixation, transportation, and burial.
COST OF LIME-SODA TREATMENT
Figure 11 shows the capital cost for lime-soda treatment plants, both
horizontal flow and upflow solids contact units. Capital costs of such
plants are primarily a function of hydraulic design capacity and are not
sensitive to the radium or hardness content of the raw water. The range
indicated by the figure includes capital costs for all raw water conditions
assumed in Table 1. These costs include costs of waste stream handling
but not waste stream disposal which are estimated later in this chapter.
Figures 12 through 14 show the annual operating and maintenance costs
of lime-soda treatment plants. Those operating costs are a function of raw
water quality, both hardness and radium, as well as plant capacity. Annual
and operating costs are shown for each of three raw water radium levels
over the range of raw water total hardness presented in Table 1; upflow
solids. These costs include costs of waste stream handling but not ultimate
disposal, which will be considered separately. Unit costs of treatment are
discussed in the unit costs section, Section IX.
COST OF LIME-SODA WASTE STREAM DISPOSAL
The dilemma facing the water industry today, and the design engineer
in particular, is that the best practicable control technology currently
available does not provide reasonable solutions for all water plant waste
treatment situations. These solutions are not reasonable for plants in
certain water production categories and for plants with unusual raw water
characteristics, since the available waste treatment methods could impose
extreme changes in treatment operations, or inordinate increases in water
production costs.
47
-------
10,000
o
o
o
O
O
1,000
100
o.i
Upflow,
Solids Contact
i i i
I i i ill
I I I I I I I I I i I I il
1.0 10
Plant Capacity MGD
100
10 100
Plant Capacity cm/day x 1,000
1,000
FIGURE 11. CAPITAL COSTS FOR LIME-SODA TREATMENT
48
-------
o
o
o
10,000
I
(/I
-^->
to
O
o
1 ,000
S-
O)
Q.
O
rd
100
10
Raw Water TH 750
300
150
pCi/1
I I I I I I I • I I I i I I i 1 11 I I 1 1 I I I l I I I I
0.
1.0
10
Plant Capacity MGD
100
1000
1.0
10 100
Plant Capacity m3/day x 1000
1000
FIGURE 12. ANNUAL OPERATING COSTS, LIME-SODA PROCESS, RWR7.5pCi/l.
49
-------
10,000
o
o
o
1000
o
o
en
c:
rd
OJ
Q.
O
c
c
<
100
10
Raw Water
TH
i i i 11
0.1
1.0
10
Plant Capacity MGD
100
1000
1.0
10 100
Plant Capacity m3/day x 1000
1000
FIGURE 13. ANNUAL OPERATING COSTS LIME-SODA PROCESS, RWR - 20 pCi/1
50
-------
10,000
o
o
o
431,000
o
o
rO
S_
O)
O-
o
100
10
0.1
Raw Water
TH
i i i i i 11 il i i i i i 1111 i i i i i 111
1.0 10
Plant Capacity MGD
100
1000
1.0
10
100
Plant Capacity nr/day x 1000
1000
FIGURE 14. ANNUAL OPERATING COSTS LIME-SODA PROCESS, RWR - 50 pCi/1
51
-------
Given the wide range of raw water characteristics, sludge production
rates, physical-chemical sludge characteristics, and numerous other variables
and constraints which face community water treatment planners, it is diffi-
cult to make meaningful cost estimates for treatment and disposal of lime-
soda sludges.
The main problem facing small plants, 10 MGD (37,850 m3/day) or less,
is the high cost of mechanical dewatering equipment. This equipment is
usually economically out of reach to these small plants. Lagoons are their
most frequently used solution.
The main problem facing large plants, above 10 MGD or 37,850 m3/day, is
the problem of finding sufficient landfill facilities to accommodate the
large volume of waste solids produced by the lime-soda process.
Lagoons
There are two types of lagoons which can be utilized for disposal of
lime-soda sludges, thickening and storage lagoons, and permanent lagoons.
Thickening and storage lagoons are used to concentrate the liquid sludge
solids by long term gravity settling to 25-40 percent dry solids by weight. The
dried sludge is then removed by draglines or other loading equipment to a
landfill or other ultimate disposal location. Permanent lagoons are used
for final disposal of sludge. In permanent lagoons the liquid sludge is
spread in thin layers and allowed to concentrate to an ultimate solids
concentration of about 70 percent.
The permanent lagoons are allowed to fill up over a period of years;
when full, they are covered with fill and the land reclaimed for limited
purposes.
Based on a loading rate of 100 Ibs solids/sq. ft./cycle (.45 hectares
per 1000 m3) , a lagoon depth of 5 feet, a construction cost of $14,000 per
acre including land, and a three-year cycle time for thickening and storage
lagoons, the unit costs of thickening and storage lagoons are very small,
for plants of 10 MGD capacity or less, being approximately $.01/1000 gallons.
Cost of ultimate disposal of the dried sludge after its removal from tem-
porary storage is discussed later in the report. Figure 15 gives the unit
costs of a permanent lagoon for ultimate disposal of lime-soda sludge as a
function of plant capacity. This estimate is based on a loading rate of 3.0
pounds solids/sq. ft./ft. of lagoon depth/year, depth of 8 feet, fill time
of 20 years, and a construction arid land cost of $14,000 per acre.
Gravity Thickening
Thickening calcium carbonate sludges by gravity alone can result in
considerable increase in solids content. The typical gravity thickener
consists of a round holding tank usually provided with rotating sludge-
scrapers and is designed to provide sufficient detention time to allow
solids to concentrate to the desired level. Economically achievable con-
centrations of dry solids for a lime-soda sludge range from about 7 to 15 per-
cent as dry solids. Figure 16 shows the unit costs for a typical gravity
52
-------
1.0
O.lOr-
0.01
to
O
O
0.001
0.0005
0.1
fO
en
1 o
o
CD
-bO-
cn
o
o
0.01
0.001
RWR 50 pCi/1
O O RWR 20 pCi/1
RWR 7.5 pCi/1
O—
J^ . . .. ...I
0.1 0.2 0.5 1 235
Plant Capacity, MGD
I I
10
1.0 10
Plant Capacity, 1000 m /day
Raw Water
TH
750
750
750
300
300
150
300
150
150
I I I I I I 11 I III
50
100
FIGURE 15. UNIT COST OF PERMANENT LAGOONS, LIME-SODA PLANTS 10 MGD
AND UNDER.
53
-------
0.50
0.10
0.01
oo
E
te-
to
o
O
0.001
0.0005
0.10
en
O
O
O
-0.01
(/I
O
0.001
0.10
— RWR 50 pCi/1
-O RWR 20 pCi/1
RWR 7.5 pCi/1
Raw Water
TH
750
750
750
300
150
150
III I I I 11
I I I I I I 11
i i i I i §1
1.0 10
Plant Capacity, MGD
I
100
500
1.0
10
100
1000
Plant Capacity 1000 m /day
FIGURE 16. UNIT COST OF GRAVITY THICKENING, LIME-SODA SLUDGE
-------
thickener. The low unit cost of gravity thickening makes this process quite
cost effective if the sludge is to be transported or mechanically dewatered
later on in the sludge handling process.
Mechanical Sludge Dewatering
The methods used to remove sufficient water from liquid sludges so as
to change the physical form to that of a damp solid are best described in
terms of the particular type of dewatering device used. The commonly used
devices include:
(1) Rotary vacuum filters
(2) Centrifuges
(3) Filter presses
(4) Horizontal belt filters.
The relationship of the various dewatering methods to those processes which
immediately precede and follow them are summarized in Table 10.
An ideal dewatering operation would capture practically all the solids
in the dewatered cake at minimum cost. The resultant cake would have the
physical handling characteristics and moisture content optimal for subse-
quent processing. Process reliability, ease of operation, and compatibility
with the plant environment would also be optimum.
Dewatering costs are extremely variable due to differences in sludge
characteristics, plant size, and location. Table 10 lists the cost range
for mechanical dewatering systems in $/ton of dry solids. As previously
mentioned, mechanical dewatering is usually limited to plants over 10 MGD
in capacity for reasons of scale economics. The unit cost of mechanical
sludge dewatering is a function of daily sludge production as well as cost of
equipment and conditioning chemicals. The unit cost can be quite variable
and no attempt will be made here to graphically portray this cost due to the
very limited amount of cost data available on the subject. Unit cost of
mechanical sludge dewatering equipment ranges between $.02 and $.15 per 1000
gallons of finished water depending upon raw water hardness and raw water
radium content. A good average figure for rough estimation would be
$.05 per 1000 gallons.
The technology and design of all available dewatering methods has been
constantly under development, particularly in the past five years. Each
type, therefore, should be given careful consideration. The applicability
of a given method should be determined on a case-by-case basis with the
specifics of any given situation being carefully evaluated, preferably in
pilot tests. 19 For further discussion of the theory and design of mechan-
ical dewatering methods see the Environmental Protection Agency Process
Design Manual, Sludge Treatment and Disposal, Chapter 7.18
Landfill
Ultimate disposal by landfill involves two major cost elements: the cost
of transportation of the sludge to the landfill and the cost of landfill
55
-------
Ln
TABLE 10. THE RELATIONSHIP OF DEWATERING TO OTHER SLUDGE TREATMENT
PROCESSES FOR TYPICAL MUNICIPAL SLUDGES18
Pretreatment
Normally Provided
Method
Rotary Vacuum Filter
Centrifuge
(Solid Bowl)
Centrifuge
(Basket)
Thickening
Yes
Yes
Variable
Conditioning
Yes
Yes
Variable
Normal Use of
Dewatered Cake
Landfill
Yes
Yes
No
Land Spread
Yes
Yes
Yes
Approximate
Cost $/ton
Dry Solids
12
20
20
- 25
- 30
- 30
Filter Presses
Yes
Yes
Yes
Variable 18 - 27
Horizontal Belt
Filters
Yes
Yes
Yes
Yes
20 - 30
-------
0.10
0.01
co
o
c:
ID
0.001
0.0005
0.2
0.1
.05
S .03
.02
CO
O
O
.01
.005
.004
.003
.002
.001
RWR 50 pCi/1
O RWR 20 pCi/1
RWR 7.5 pCi/1
—O —
Raw Water
TH
750
750
750
300
300
150
300
150
150
I I I I 8 I I
I I I I
0.1 0.2
0.5 1.0 2.0 5.0 10 20 30
Plant Capacity, MGD
50 100 200
500
1.0
1000
10 100
3
Plant Capacity, 1000 m /day
FIGURE 17. UNIT COST OF TRANSPORTING 10% SOLIDS LIME-SODA SLUDGE BY TRUCK OVER A 5-MILE ONE-WAY HAUL
-------
600
400
oo
ro
03
£200
oo 60
o
o
c:
O
o
CL
00
E
n3
S-
40
20
Tank Truck
Railroad Tank Car
-Pi peline
I
I
I
1
20
40 60 100 200
Distance to Disposal Point, miles
400
FIGURE 18. RELATIVE TRANSPORTATION COST FOR LIQUID ORGANIC
SLUDGES 18
58
-------
1.0
1.00
0.10
oo
O
o
fd
en
O
O
O
So.10
0.01
0.005
0.01
0.10
. . . . . ..1
i i i i i i 11
.— RWR 50 pCi/1
—O RWR 20 pCi/1
RWR 7.5 pCi/1
1.0
10
Plant Capacity, MGD
i ii i i 1 1
1
00
Raw Water
TH
750
750
750
300
300
150
300
150
150
500
1.0
10
100
Plant Capacity 1000 m /day
1000
FIGURE 19, UNIT COST OF SANITARY LANDFILL, 10% SOLIDS LIME-SODA SLUDGE
-------
0.50
0.10
0.10
oo
0.01
to
O
to
en
O
O
O
-M
co
O
50.01
0.001
0.0005 L
0.001
0.1
1.0
10
Plant Capacity, MGD
RWR 50 pCi/1
—O RWR 20 pCi/1
—. RWR 7.5 pCi/1
f » I t » 8 1
IOC
Raw
Water
TH
750
750
750
300
300
150
150
. ,_ I
500
1.0
10
100
Plant Capacity 1000 m /day
1000
FIGURE 20. UNIT COST OF SANITARY LANDFILL, 50% SOLIDS LIME-SODA SLUDGE.
-------
operation itself. Sludge can be transported by truck, rail, or pipeline in
liquid form (up to about 6 percent solids), thickened condition (up to
about 15 percent solids), or dewatered condition (above 25 percent solids -
truck or rail only).
Generally speaking, the economics of sludge disposal improve (1) if
sludge volume is reduced by removing water, (2) per unit basis as volume of
sludge increases, and (3) if sludge can be sold to reduce operating costs.
Figure 17 shows the unit costs of transporting thickened sludge (10 per-
cent solids) by truck over a five mile (one-way) haul, based on a typical
hauling cost of $6.00 per ton solids. Figure 18 is a comparison of transportation
costs of pipeline, tank truck, and rail hauling for long distance hauls of
liquid sludge (about 5 percent solids). It can be seen from this figure
that railroad hauling becomes more economical than truck hauling at a distance
of about 150 miles. Pipeline transportation is the least expensive of all the
transportation methods up to a distance of about 200 miles, however, the
large capital cost of pipeline and their inherent lack of flexibility in
terms of disposal location makes this alternative less favorable for most
applications.
The unit costs for construction and operation of sanitary landfills are
shown in Figures 19 and 20. Figure 19 is for sludge of 10 percent solids
and Figure 20 is for sludge of 50 percent solids.
Costs of spreading sludge on farmland, disposal in strip mine areas, etc.
are extremely variable and can best be estimated by the planner using trans-
portation costs from Figures 17 and 18, and sanitary landfill costs from
Figure 19 and 20. Adjustments can be made to the construction cost of the
landfill if development costs of farmland, spreading, and strip mine disposal
are known.
61
-------
SECTION VII
ION EXCHANGE SOFTENING
GENERAL
Water softening by the ion-exchange process depends upon the ability of
certain insoluble substances to exchange cations with other cations dissolved
in water. When a hard water is passed through a sodium cation exchanger,
the calcium and magnesium in the hard water are replaced by sodium for the
exchanger; and because this reaction is reversible, after all of the readily
replaceable sodium has been exchanged for calcium and magnesium from the
hard water, the "exhausted" cation exchanger can be regenerated with a
solution of sodium chloride (common salt). In the regeneration process, the
calcium and magnesium of the exhausted cation exchanger are replaced with a
fresh supply of sodium from the regenerating brine solution. Then, after a
washing with water to free it from brine, the regenerated exchanger is ready
to soften a fresh supply of hard water23.
Various materials with cation exchange properties, some naturally
occurring and some synthetic, are used as exchange media for softening by ion
exchange. The most widely used materials, however, are the various forms of
synthetic styrene divinyl benzene copolymer resins which possess large
exchange capacities, resistance to dissolution over a wide pH range, and
great mechanical strength. The typical polystyrene type resin has an ex-
change capacity in the range of 18,000 to 30,000 grains of hardness per cubic
foot of material. The capacity of the resin is a function of the amount of
salt used in regeneration. For example, a resin with a capacity of 24,000
grains of hardness per cable foot when regenerated with 0.25 Ib. of salt per
1,000 grains of hardness removed will have an increased capacity of 30,000
grains when regenerated with twice the amount of salt. Economic considera-
tions are the controlling factor when balancing capacity with amount of salt
used in regeneration. The concentration of the salt solution used in re-
generation also plays an important role in determining the exchange capacity
of the media. Media regenerated with sea water or connate brines are not as
high in capacity as when regenerated with a concentrated salt solution.
The generalized chemical reactions of the cation-exchange process are as
follows:
a) Softening
Ca"1"1" + 2NaR -> CaR2 + 2Na+
Mg*4" + 2NaR -> MgR + 2Na+
62
-------
b) Regeneration
CaR2 + 2Na -*•• Ca + 2NaR
MgR2 + 2Na+ -v Mg44" + 2NaR (Eq. 19-A)
Hardness removal in an ion-exchange unit is essentially complete (ap-
proaching 100 percent) . High sodium, levels in the raw water, incomplete rinsing
of the media during regeneration, and other practical considerations can
cause "leakage" of a few parts per million calcium and magnesium ions so
that hardness removal is usually somewhat less than 100 percent.
Polystyrene resin exchange media are also capable of being regenerated
by strongly acid solutions. The exchanger is then said to operate in the
hydrogen cycle. In the hydrogen cycle the hardness cations exchange with
a hydronium ion, thereby neutralizing some of the alkalinity of the treated
water and decreasing pH. Water treated by the hydrogen cycle is usually
blended with raw water in "split treatment" in order to adjust the pH of the
treated water. Split treatment is used in only a few specialized locations
in the United States and will not be discussed further in this report.
The advantages of ion-exchange softening are:
1) Ease of operation and control. Many I/X plants are completely
automated reducing need for labor.
2) Finished water hardness can be closely controlled by blending
treated water with raw water in varying amounts.
3) Costs can be held quite low for small plants.
4) Treated water alkalinity is not affected by sodium cycle operation.
5) Trace amounts of heavy metals, as well as radium, are easily
removed.
Some disadvantages of the I/X process are:
1) Finished water shows an actual increase in total dissolved solids
since one calcium ion of atomic weight 40 is replaced by two
sodium ions of total atomic weight 46.
2) Sodium concentrations can be elevated above recommended concentra-
tions for control of hypertension and cardiovascular diseases.
3) Raw water requires pretreatment if considerable amounts of turbidity
and suspended solids, iron and manganese, or bacterial slimes are
present.
4) Finished water may be corrosive in distribtuion lines unless some
form of stabilization is practiced.
63
-------
5) Disposal of spent brines can be problematic. Regulatory agency
approval is often difficult to obtain.
An ion-exchange water softening unit resembles an ordinary mechanical
sand filter with ion exchange mineral substituted for sand. This filter may
be the pressure type device or the open gravity type similar to those used
at large water purification plants. The pressure softener consists of a
closed steel cylinder which may be of the vertical or horizontal type. If
tanks are to be shipped assembled, the diameter must be limited to about 10
to 11 feet because of shipping regulations. There are a number of 14-foot
steel welded units in operation. Gravity or open-top softeners usually are
built of concrete and are rectangular in shape, although some round steel
units have been built. The pressure type has one advantage over the open-
type softener in that it is possible to pump the water to be softened directly
from the source of supply through the softener into the distribution system,
thus obviating double pumping. Gravity filters have an advantage in that it
is possible to observe their condition readily, and to see whether or not
there is any channeling of the water or brine through the bed, or any mineral
being washed out.24 Figure 21 shows a typical ion-exchange softening system.
RADIUM REMOVAL IN THE ION EXCHANGE PROCESS
Table 11 lists radium removal efficiencies and associated hardness
removal efficiencies for ion-exchange plants. Figure 22 portrays this
information graphically. It is readily seen that radium is removed with
high efficiency by the ion-exchange process. The plants whose radium removal
efficiencies were less than 90 percent were • those whose plant operation was
characterized by either operation past normal breakthrough or incomplete
regeneration of the resin. It should be noted that some of the plants listed
in Table 11 included iron and manganese removal as pretreatment prior to ion
exchange. This was usually accomplished by aeration and filtration.
Although these processes were successful in reducing iron and manganese,
reduction of radium in pretreatment was insignificant and will not be further
discussed.
It is interesting to note that radium is removed with greater efficiency
than calcium or magnesium. There also appears to be a built-in safety factor
in that radium continues to be removed with a fairly high efficiency, -85
percent removal, even after hardness breakthrough occurs.
For purposes of this report, a 95 percent radium efficiency removal at
95 percent total hardness removal was chosen at the practically achievable
result in a well designed and operated ion exchange plant.
REQUIRED TREATMENT FRACTION
Figure 23 indicates the overall schematic of an ion-exchange plant. The
basic design considers a bypass fraction and a treated fraction which are re-
blended to achieve the required water quality. When both total-hardness remo-
val and radium removal are assumed to be 95 percent, the fraction of raw water
to be treated in the ion exchanger to achieve a finished-water concentration
of 5 pCi/1 can be calculated as a function of raw water radium concentration
64
-------
WASH-WATER
COLLECTOR
OUTLET
REGENERANT TANK
FIGURE 21. DIAGRAM OF TYPICAL ION EXCHANGE UNIT
65
-------
TABLE 11. RADIUM REMOVAL IN ION EXCHANGE PLANTS
Plant
Eldon, IA
Estherville, IA
Grinnell, IA
Holstein, IA
Dwight Corr.
Ins t . , IL
Herscher, IL
Lynwood , IL
Sarasota, FL
Ra in
pCi/1
49
5.7
6.7
12
3.26
14.31
14.69
4.3
Ra out
pCi/1
1.9
0.3
0.2
0.5
0.36
1.31
0.41
0.70±
% Ra
Rem.°
96
95
97
96
89
91
97
84
TH in
mg/lCaC03
375
915
385
920
286
406
848
460
TH out
10
46
11
18
43
60
78
159±
% TH
Rem.°
97
95
97
98
85*
85*
91
65**
0 Removed
± Adjusted to take account of raw water blending.
* % hardness and % Ra removals are somewhat low due to breakthrough
occurring prior to all samples being collected.
** % hardness and % Ra removals are somewhat low due to incomplete
regeneration of media as 1/2 brine pumping capacity was down for
repair.
66
-------
1.00
o
-(->
o
rd
>
o
CD
.80
.60
.40
i 1 • _i I i i ill
.20 .40 .60 .80 1.00
Total Hardness Removal Fraction
FIGURE 22. RADIUM REMOVAL FRACTION VS. TOTAL HARDNESS REMOVAL
FRACTION IN ION EXCHANGE PLANTS (BEFORE BLENDING)
67
-------
Raw Water
f2.1
f2Q
Bypass
Water
Ion
Exchange
Unit
Finished
Water
FIGURE 23. MASS BALANCE FOR DETERMINING FRACTION OF RAW WATER
TO BE TREATED
68
-------
and is portrayed in Figure 24. The fraction of raw water blended is one
minus the fraction treated.
A mass balance to achieve a finished water at 5 pCi/1 yields
Fraction Treated = 1.053 (1 - (5/RWR)) (Eq. 20)
Design and costs calculations for ion exchange were based on the above
mentioned premise that finished-water concentration of radium would equal
the limit of 5 pCi/1. It is again to be noted that many communities may
desire water treated to a greater degree of hardness removed for aesthetic
or health reasons. Further treatment would increase the costs above those
listed in this report.
The lifetime of the unit depends upon its size and upon the total hard-
ness to be removed. The populations to be served range from 100 to 50,000
people. This project will assume a flow of 150 gpcd and three hardness
levels as in previous calculations.
BRINE PRODUCTION
The total volume of wastewater generated is a direct function of the
total hardness and the volume treated. See Figure 25. Mathematically,
Total Wastewater Rate (brine and rinse) = 105 TH, gal/MG (Eq. 21)
The best available data11 indicate that 78 percent of the removed radium
goes to the brine solution effluent and 13 percent comes out in the back-
wash. This report will assume that 91 percent of the radium removed from
the treated stream will be mixed into the total wastewater flow of backwash
and brine combined. The remaining 9 percent must remain on the resin and
a build-up occurs with this model.
The resulting concentration of radium in the total wastewater will be:
Wastewater Radium Concentration, pCi/1 = 9524 (RWR - 5)
Total Hardness, mg/1
(Eq. 22)
for RWR > 16 pCi/1
Wastewater Radium Concentration, pCi/1 = 6572 (RWR)
Total Hardness, mg/1
(Eq. 23)
for RWR < 16 pCi/1
69
-------
-o
0)
-(->
to
CD
S-
c
o
o
to
S-
0.00
30
Raw Water Radium, pCi/1
40
50
FIGURE 24. FRACTION OF WATER NEEDED TO BE TREATED AS A FUNCTION OF RAW WATER RADIUM
CONCENTRATION - ION EXCHANGE
-------
TH
750
650
550
M50
to
O)
I 350
to
2250
150
50
10,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000
Total Wastewater Volume, gal/MG Treated
FIGURE 25. GENERATION OF WASTEWATER VOLUMES WITH ION EXCHANGE
71
-------
These expressions are shown graphically in Figure 26. It is interest-
ing to note that the radium concentration increases with decreases in the
total hardness of the raw water. This is a consequence of the exchange unit
being on line for a longer time at a given radium concentration when the
total hardness to be removed is less. Values of the radium concentrations
range from about 3000 pCi/1 when the raw water radium is slightly over 50
pCi/1 and the total hardness is 150 mg/1 to a little over 50 pCi/1 at raw
water radium of 6 pCi/1 and a total hardness of 750 mg/1.
BRINE DISPOSAL
One of the problems created by sodium ion-exchange softening is the
disposal of spent brine from the regeneration cycle. In view of the in-
creasing water pollution control requirements, these high salinity waters
may face severe limits on discharge. This disposal problem becomes even
more sensitive when the waste may contain elevated levels of radium.
The backwash water preceding the regeneration cycle may contain small
amounts of iron or organic material. It is not clear whether it will also
contain measurable quantities of radium when the unit is used for raw waters
containing high radium concentrations. Both backwash and brine will be
considered as one combined wastewater in this report.
The waste products from the brine and rinse cycle are composed princi-
pally of the chlorides of calcium and magnesium and the excess salt neces-
sary for regeneration. The total solids in a composite sample may vary from
an average concentration of 50,000 to 100,000 mg/1 to a maximum of 70,000 to
200,000 mg/1.
Disposal techniques may often be limited by considerations of salinity
rather than radium concentration. A list of potential alternatives for
handling the wastewater streams follows:
I. Discharge
A. To sanitary sewer
B. To local receiving water
1. Streams
2. Oceans
II. Storage
A. Evaporation lagoons
B. Land spreading
72
-------
O)
c
fO
o
X
c
o
01
o
£Z
O
E
13
-a
O)
01
ra
4->
O
0.00
4.00 r- X 10
3.50 -
3.00 -
2.50 -
2.00 -
1.50
1.00 -
0.50
6.0
16.0
46.0
26.0 36.0
RWR, pCi/1
FIGURE 26. RADIUM IN ION EXCHANGE WASTE WATERS (BRINE PLUS BACKWASH)
-------
III. Utilization - Recovery
IV. Disposal
A. Deep aquifers
B. Oil well fields
C. As nuclear wastes
Discharge to Sewers
Shunting the wastewaters to sanitary sewers taxes the biological process
of the waste treatment plant. In addition, much of the salinity added to the
system will be eventually added to the receiving watercourse. However, there
will be some dilution (100 gpcd of sewage) and some fractionation into the
digested sludge. The latter phenomenon may produce a sludge that is unsuited
for many of the normal uses of sewage sludge.
Discharge to Watercourse
Release of the wastewater brines from ion exchange may present a more
significant problem with the salinity increase than from a radiological point
of view.
If the discharge flow and the background radium concentration in the
river are neglected, a simple balance shows that limited dilution is necessary:
FLOW = 31.6 (Pop., millions)(RWR - 5) (Eq. 24)
where FLOW is the river water flow in MGD necessary to dilute the effluent
to a radium level of 5 pCi/1. The expression for various population ranges
is graphically presented in Figure 27. Note that, even at a high radium
level in the raw water and a population of 50,000, the required flow is less
than 100 MGD.
If salinity and water quality standards are still incompatible, con-
trolled dilution may be considered. Short term holding tanks or long-term
lagoons will serve the purpose of allowing discharge at seasonally higher or
other daily increases in streamflow. Costs, other than transportation,should
be less than $0.01/1000 gallons.
Ocean outfalls are applicable to only a limited area since transportation
costs rise rapidly with distance.
Evaporation Lagoons
Evaporation ponds may afford an effective method of brine disposal if
the following conditions exists: (1) the net-evaporation rate (gross annual
evaporation minus annual rainfall) exceeds approximately 40 in. per year;
74
-------
Ul
1000 .-
1000
100
o
o
o
X
to
-a
100
10
oo
o 10
s_
OJ
t 1.0
O)
1.0
O)
S-
cr
O)
0.10
0.01
6.0
16.0
Pop = 50,000
26.0 36.0
Raw Water Radium, pCi/1
46.0 50.0
FIGURE 27. RIVER WATER FLOW REQUIRED TO DILUTE ION EXCHANGE BRINE TO 5 pCi/1.
-------
(2) the net evaporation occurs at a uniform rate throughout the year; and (3)
the impounded water is kept at shallow depths. These conditions are deter-
mined for fresh water. Since the effect of salinity increase in brine dis-
posal ponds will reduce the rate of evaporation, disposal ponds must be
designed to account for the difference in evaporation rate between fresh and
saline water.
Figures 28a and 28b indicate the regional differences in rainfall and
evaporation in the United States.25 Local differences may change relative
numbers considerably. Temperatures, wind movements, altitude, and topo-
graphical features all contribute to these changes.
Only lined ponds are considered for brine effluent disposal. Generally,
unlined ponds permit wastes either to seep downward, contaminating usable-
quality groundwater, or move laterally through the pond dike and subsequently
into surface watercourses. Experience has shown that many "watertight" ponds
are seepage ponds. Liner thickness should be 20-mil polyvinyl chloride (PVC)
or thicker.
A dike height of 8 ft was selected by OSW25 and is based on the following
design criteria:
Assumed depth of effluent 4.0 ft
Depth to accommodate precipitate 0.5 ft
Freeboard for rainfall 0.5 ft
Freeboard for wind 2.0 ft
Soil cover over liner 1.0 ft
Total dike height 8.0 ft
The procedure covers pond sizes up to one thousand acres. In all cases,
the pond is assumed to be square, as this configuration yields minimum costs.
Finally, the disposal of residual salts is an extremely difficult pro-
blem. If the pond is covered with soil, the fate of vegetation in the cover
is uncertain. Transportation costs are high, even if suitable locations for
disposal could be found. Some possible sites are salt mines, strip mines, and
abandoned mines of other types. Radium concentration in the final salt may
exceed 106 pCi/kg.
Landspreading
Discharge of brine wastes onto large land areas can be expected to
create serious problems with cover vegetation. Although the land may serve to
"absorb" large quantities of the salt before contamination of the ground-
water is expected, the land may be permanently relegated for no other use.
Landspreading does not appear to be a viable disposal alternative.
Recycle of Brine
Schlickelman12 has detailed the problems in brine reclamation: "Only a
portion of the partially spent brine could be used for subsequent regeneration.
76
-------
100 +
inches/year
FIGURE 28a. AVERAGE RAINFALL INCLUDES ALL FORMS OF PRECIPITATION
30-40
inches/year
FIGURE 28b.
RATE OF EVAPORATION INDICATES ABILITY TO EVAPORATE, NOT
ACTUAL EVAPORATION
77
-------
In general the first one-third of the spent brine from the brine rinse would
contain 80 percent of the hardness. These calcium and magnesium ions interfere
with the regeneration and decrease the exchange capacity. The middle one-third of
brine rinse is high in sodium and might be used in subsequent regenerations
to backwash the softener or used initially in the regeneration followed by
sufficient fresh brine to attain the desired capacity. The principle of mass
action requires an excess of salt for regeneration. Some reduced salt costs
and a reduction in the amount of spent brine requiring disposal are benefits
for reclamation which must be weighed against costs of additional piping and
spent brine holding tanks.
Radium presents a complex problem that is not well understood. It is
likely that the radium will be more tightly bound than calcium or magnesium.
Therefore, the radium may be more concentrated in -the middle-third of the
brine. The long-term effect may be an earlier breakthrough of the radium and
overall design removal may become less than 95 percent.
Brine Injection Wells
Brine wells for injection into deep aquifers may provide a means of
disposing of the spent brine. It may be more feasible in the oil field well
areas. Brine treatment may also be necessary for conditioning before injec-
tion into the formations. Radium levels are of no concern to the design',
however, this method represents a highly desirable procedure for the radium
disposal.
It must be assumed that zones or formations exist with suitable geologic
characteristics for receiving the injected waste.
If an injection program is properly planned and implemented, the injected
brine should remain in the receiving formation indefinitely, with little
danger of pollution or destruction of other natural resources. A successful
injection program requires the technical services of qualified geologists
and engineers.
Very stringent criteria for disposal wells are needed to prevent pollu-
tion where subsurface injection is selected as a means of disposal. State
regulations usually require that the injection well must be drilled and
constructed in such a manner as to prevent brine from escaping from the
disposal zone, or well, and polluting usable ground or surface waters. In
part, this requires that surface casings be set through formations containing
fresh groundwater and fixed permanently by circulation of cement from the
bottom of the casing to the ground surface. The injection zone selected
should not be one containing water of usable quality- It should have ample
holding capacity for the injected waste^ Casings should be set and cemented
in such a manner as to ensure that the disposed brine will be confined in the
injection zone. Where applicable, existing oil and gas reservoirs must be
adequately protected.
The geological characteristics of a zone or formation described as suit-
able are:
78
-------
(1) The zone must be deep enough to prevent communication of fluids
between the injection zone and aquifers containing usable ground
water,
(2) The fluid in the reservoir and the fluid to be injected must be
compatible,
(3) The reservoir must be capable of receiving and containing the brine
from the desalting plant over the life of the plant, and
(4) The zone must have sufficient porosity, permeability, thickness,
areal extent, and low reservoir pressure in order to act as a stor-
age reservoir at safe injection pressure.
As porosity, permeability, and formation thickness increase,annual dis-
posal cost will decrease. However, as reservoir pressure and depth of the
well increase, the injection cost will increase. Conversely, the opposite
trend will occur in each case for decreases in these formational characteris-
tics.
Treatment as a Nuclear Waste
If the first two-thirds of the spent brine were separated from the rinse
and the final brine, then the volume to be handled would be somewhat reduced.
Also, most of the radium would probably appear in this fraction. Evaporation
of the general type used in nuclear plants, but without the off-gas cleanings
and radiological monitoring features,could be used to obtain a sludge suitable
for fixation, containment, shipment and burial. The evaporation cost may be
expected to exceed $30.00/1000 gallons of brine or about $1.50 per 1000 gallons
of water treated. Additional monies must be added for burial, and transpor-
tation costs will produce a third cost increment after a site is located.
COSTS OF ION EXCHANGE SOFTENING
Figures 29, 30, and 31 give the capital cost and Figures 32-34 give the
annual operating costs of ion exchange softening plants for raw water radium
concentrations of 7.5, 20 and 50 pCi/1, respectively.
It can be readily seen that for ion exchange, capital and annual operat-
ing costs are strongly a function of the concentrations of radium and hardness
in the raw water. These costs do not include the costs of ultimate disposal
of regeneration brines which will be discussed later in this report.
BRINE DISPOSAL COSTS
Several methods for brine disposal were considered for detailed calcula-
tions: lined evaporating ponds, pipeline and transmission, subsurface in-
jection, and treatment as a nuclear waste. Assumptions and curves follow.
Costs of brine disposal by lined evaporating ponds assumed a net evapora-
tion of five feet per year26 and a land costs of $1850 per acre. Capital
costs included land, construction, vinyl lining, engineering design, and
79
-------
o
o
o
1000
CO
O
o
CL
ro
0 100
10
0.01
RWR = 7.5 pCi/1
TH
0.1 1
Plant Capacity, MGD
I
10
0.1
10 20
Plant Capacity, m3/Day
FIGURE 29. CAPITAL COSTS OF ION EXCHANGE PROCESS, RWR = 7.5 pCi/1
80
-------
g 1000
o
x
•to-
CL
rc
O
100
10
TH
. I
I
..I
0.01
0.1 1
Plant Capacity, MGD
I
10
0.1
1
10
20
Plant Capacity, m3/Day
FIGURE 30. CAPITAL COSTS OF ION EXCHANGE PROCESS, RWR = 20 pCi/1
81
-------
1000
o
o
o
X
-------
1000
o
o
o
X
t/l
o TOO
-------
1000
o
o
o
100
O
O
OJ
O
c
fO
c
-------
TH
1000
o
o
o
100
cu
CJ
E
"3
c:
O)
4->
C
-a
fd
01 10
ns
O>
0.
o
fd
0.01
I I I I 11
0.1 1
Plant Capacity, MGD
10
0.1
1 10
Plant Capacity m^/Day
20
FIGURE34. ANNUAL OPERATING AND MAINTENANCE COSTS OF ION EXCHANGE,
RWR = 50 pCi/1.
85
-------
contingency. Operation and maintenance costs included all labor, including
payroll extras and overhead as well as supplies and repair of equipment.
Figure 35 summarized the unit costs for different radium concentrations and
total dissolved solids.
Costs of brine transmission to an outfall assumed one mile of pipeline
and one pumping station.26 Outfall costs were considered negligible. Capital
costs included pipeline, pumping station, and right-of-way costs. Operating
and maintenance costs included power labor and overhead. Figure 36 summarizes
the final unit costs as a function of radium concentration and total dissolved
solids.
Subsurface injection costs were calculated with basic assumptions26 of
3000 ft depth, well-head pressure of 500 psi, an aquifer permeability of 135
millidarcies, and a porosity of 5 percent. Capital costs included wells,
well-field distribution system, pumping station, storage, engineering and
design, interest during construction, and contingency. Not included were
environmental impact assessments required by many states. Operation and
maintenance costs included power, supplies, labor and overhead. Figure 37
indicates the unit costs for different radium concentrations and total dis-
solved solids.
86
-------
loo r
0.10
CO
O
O
0.01
0.005
1.00
CD
O
O
O
J0.10
0.01
0.01
RWR = 50 pCi/1
O o O RWR = 20 pCi/1
RWR = 7.5 pCi/1
TDS 2000
— IDS 4000
0.10
1.0
Plant Capacity, MGD
I
10
I
0.1
100
100
1 10 20
Plant Capacity 1000 m3/day
FIGURE 35. UNIT COSTS OF WASTE DISPOSAL BY LINED EVAPORATING PONDS, ION EXCHANGE.
-------
00
00
1.0
1.001-
0.1
o.oiL
(O
CD
O
o
o
0.1
o
o
0.01_
0.01
I I I I I I I I I
RWR = 50 pCi/1
O o O RWR = 20 pCi/1
RWR = 7.5 pCi/1
I I I I I I I I
IDS 2000
I I I
0.10
1.0
Plant Capacity, MGD
I
10
0.1
1
10
FIGURE 36.
Plant Capacity 1000 m3/day
UNIT COST OF WASTE BRINE TRANSMISSION; PER MILE OF PIPELINE, ION EXCHANGE.
20
-------
00
i.QOr
i.oo
CO
L0.10
CO
o
O
CO
•8
o
CO
O
C_5
:o.io
o.oi
0.005
o.oi
RWR = 50 pCi/1
O O o RWR = 20 pCi/1
—— RWR = 7.5 pCi/1
0.01
I I L^ i I I i i I
i l I l l I i i I
IDS 400
IDS 2000
IDS 2000
IDS 2000
IDS 400
-X* I TDS 400
i i i i i 111 i i i
0.10
1.0
Plant Capacity, MGD
10
10
20
TOO
Plant Capacity 1000 m/day
FIGURE 37. UNIT COST OF WASTE DISPOSAL BY SUBSURFACE INJECTION, ION EXCHANGE.
-------
SECTION VIII
REVERSE OSMOSIS
GENERAL
Osmosis (Figure 38a) is the spontaneous passage of liquid from a dilute
to a more concentrated solution across an ideal semipermeable membrane that
allows passage of the liquid but not of dissolved solids. Obviously, reverse
osmosis is a process in which the natural osmotic flow is reversed. Reversal
(Figure 38b) is effected by the application of pressure to the concentrated
solution sufficient to overcome the natural osmotic pressure of the less-con-
centrated (dilute) solution. When the amount of water passing in either direc-
tion is equal, the applied pressure can be defined as the osmotic pressure of
the dilute solution having that particular concentration of solutes.
In practical applications, pumps are used to supply the pressure to over-
come osmotic pressure. The water flow rate through the membrane is dependent
principally upon the net driving pressure. The solute flow rate through the
membrane is dependent almost solely upon the solute concentration of the feed-
water.
Figure 39 illustrates a typical reverse osmosis installation. A single
pressure vessel containing the membrane is shown, but there normally would be
a number of pressure vessels arranged in a series-parallel array. A pump
continuously feeds the pressure vessel, and the back pressure valve on the
concentrate stream controls the pressure within the vessel and against the
membrane. Increased pressure increases the transport rate of the permeate.27
Currently, there are two predominant membrane configurations: the spiral-
wound module, and hollow fine fiber. The spiral-wound module (Figure 40a and
40b), was developed by Fluid Systems Division of Universal Oil Products (form-
erly Gulf Environmental Systems Company) in the mid-1960's, under the sponsor-
ship of the Office of Saline Water, U.S. Department of the Interior. In this
configuration, a product water collection channel is formed between two sheets
of membrane by a fabric sealed in place on three of the four laminate edges.
The fourth edge of the laminate is attached to a central tube, which has
openings for collecting the permeate from the backing material. A mesh screen
over the membrane rejection surface forms a feedwater flow channel through the
module as the composite is wound around the central tube. An outer wrap is
applied to maintain the modular configuration. The result is a compact pack-
age that is efficient, economical, and applicable to a wide variety of feed-
waters .
90
-------
Serni permeable
Membrane
Concentrated
Solution
Fresh Water
FIGURE 38a. OSMOSIS - NORMAL FLOW FROM LOW-CONCENTRATION SOLUTION TO
HIGH-CONCENTRATION SOLUTION 27
Pressure
Semi permeable
Membrane
Concentrated
Solution
Fresh Water
FIGURE 38b. REVERSE OSMOSIS - FLOW REVERSED BY APPLICATION OF PRESSURE
TO HIGH-CONCENTRATION SOLUTION 27
91
-------
FiIter
Pump
(400-600 psi)
Pressure Vessel
Membrane
Pressure
Regulating
Valve
pH Adjustment
(5.0-6.5)
Concentrate
Monitor
Permeate
(Demineral ized
Water)
FIGURE 39. TYPICAL REVERSE OSMOSIS SYSTEM 27
-------
Wind-up
Product Water
Tube, Perforated
in Area Under Product
Water Collection
Backing Material
F|l Product Water Collection Backing Materia'
[| Reinforced Membrane
lip Feed Channel Screen
Rv| Glue Line
FIGURE 40a. SPIRAL-WOUND MEMBRANE CONFIGURATION27
Feed Water
Brine Seal
FIGURE 40b. HOLLOW FIBER MEMBRANE CONFIGURATION27
93
-------
The hollow fine fiber configuration (Figure 40b), which uses nylon as
the membrane, was developed by DuPont in the late 1960's, and later was used
by Dow Chemical. DuPont now uses aromatic Polyamide membrane and Dow uses
cellulose triacetate.
In the hollow fine fiber configuration, the membrane material is spun
into hair-like fibers having an outer diameter of 85 to 100 microns. The fi-
bers are bundled and potted into a header, all enclosed in a fiberglass or
metal vessel. Feedwater enters the center of the vessel and is distributed
radially over the bundles. Water under pressure permeates the fiber and
travels inside to the permeate collection header. The wastewater continues
radially over the fiber bundle and through the housing. Hollow fine fiber
systems provide simplicity of installation, comparable economics to the spiral-
wound system and the best packing density.28 This membrane configuration is
more susceptible to clogging, however, than the spiral-wound configuration.
The pumping pressure required to provide the driving force in the re-
verse osmosis process is a direct function of the concentration of dissolved
solids in the feed. Reverse osmosis applications have been primarily for
feedwater with TDS above a minimum of 2000 mg/1, and usually in the range
of 4000-35,000 (sea water) mg/1 TDS.
A characteristic of semipermeable membranes used for reverse osmosis is
their greater rejection of multivalent ions such as Ca++, Mg++, Ra++, SO =,
etc. than for monovalent ions Na , Cl~, etc. Membranes which "soften" water
by removing primarily the divalent while passing the monovalent ions are under
development and may reduce the pressure requirements, and hence the cost, of
softening with reverse osmosis. As of this date, no full-scale membrane
softening plant is in operation and membrane_ softening will not be discussed
further.
The primary advantage of the reverse osmosis system is its high rate of
rejection of dissolved solids in the raw water. This rejection rate allows
brackish and saline water to be desalted for potable use. There are several
disadvantages to R/0 including:
(1) high initial and operating costs
(2) need for pretreatment of raw water with turbidity removal, treat-
ment with acid and other chemicals to prevent fouling of the
membranes by slimes, suspended solids, iron, manganese, and
precipitation of calcium carbonate and magnesium hydroxide.
(3) requirement to stabilize finished water with lime or other
chemicals to prevent corrosion in distribution system.
RADIUM REMOVAL IN REVERSE OSMOSIS
Table 12 presents radium removal data from the two reverse osmosis
plants for which radium removal data were obtained. The Greenfield, Iowa
plant removed 93 percent of Ra226. The difference between the two values
is due to the greater passage of monovalent ions through the membrane.
94
-------
Total dissolved solids removal data were not available for the Sarasota,
Florida plant which also removed 96 percent of Ra226. It will be assumed,
for purposes of this report, that a well-operated and designed reverse
osmosis unit can remove 95 percent of the influent radium activity.
TABLE 12. RADIUM REMOVAL IN REVERSE OSMOSIS PLANTS
Plant Ra in Ra out % Ra TDS in TDS out % TDS
pCi/1 pCi/1 Rem. mg/1 mg/1 Rem.
Greenfield, IA 14.0 0.6 96 2160 164 92
Sarasota, FL 22.0 0.8 96 -
REQUIRED TREATMENT FRACTION
Figure 41 indicated the overall schematic of a reverse osmosis plant.
The basic design considers a bypass fraction and a treated fraction which are
reblended to achieve the required water quality. The extra raw water
required for the concentrate will be neglected at this point. When both
total hardness removal and radium removals are assumed to be 95 percent, the
fraction of raw water to be treated in the reverse osmosis unit to achieve
a finished water concentration of 5 pCi/1 can be calculated as a function of
raw x^ater radium concentration and is portrayed in Figure 42. The fraction
of raw water blended is one minus the fraction treated.
A mass balance to achieve a finished water at 5 pCi/1 yields:
Fraction Treated = 1.053 (l-(5/RWR)) (Eq • 25)
Design and costs calculations for the reverse osmosis unit were based on
the above-mentioned premise that finished water concentration of radium
would equal the limit of 5 pCi/1. It is again to be noted that many commu-
nities may desire water treated to a greater degree of hardness removed for
aesthetic'or health reasons. Further treatment would increase the costs
above those listed in this report.
Because the waste concentrate is such a large portion of the treated
flow, it cannot be considered as negligible. Figure 43 shows a schematic
of the reverse osmosis process in more detail. It can be readily observed
from this diagram that the raw water demands will exceed the finished xrater
flow by the product of the fraction treated and the brine to product ratio
for the unit.
95
-------
Raw Water
V f2 = i
f2Q
Bypass
Water
Reverse
Osmosis
Unit
Finished
Water
FIGURE 41. MASS BALANCE FOR DETERMINING FRACTION OF RAW WATER
TO BE TREATED.
96
-------
1.00 r
0.90
tu
4->
-------
Raw Water
Flow
(1 - fi) Q
0 - fl) Q
[(i-fi) + f3fi + fi I Q » OR
(1 + f3fi) Q
95% Removal
of Radium
R/0
Q - Finished Water Flow
FIGURE 43. DETAILED SCHEMATIC OF REVERSE OSMOSIS PROCESS
98
-------
Radium in Reverse Osmosis Brines
Table 13 indicates the calculations for predicting the brine flows in
reverse osmosis. Figure 43 is used to determine the mass balances. The total
brine depends upon the flow rate of finished water, the total dissolved solids
concentration and the radium concentration in the raw water. However, the low
and medium solids calculations are identical and the family of two curves will
suffice predicting expected radium concentrations in the brines; one for less
than 1500 mg/1 TDS and one for greater than 1500 mg/1 TDS . When the finished
water radium is plotted versus the raw water radium in Figure 44 the two ex-
pressions result:
Brine to Finished Water Ratio = 43 9 + 2 84 RWR ^Eq>
for TDS = 2000 mg/1
and
Brine to Finished Water Ratio =
i OQ 5 + 6 99 RWR
for TDS = 1000 mg/1 or less.
Radium contents in the waste brine can be determined with the following
expression:
Brine Radium Concentration, pCi/1 = RWR
1 + 0.95
fraction treated
brine to product
ratio _
(Eq. 28)
When Equations 26 and 27 are substituted into Equation 28 the radium con-
centration in the brine becomes a function only of the raw water radium con-
centration :
^~ 1.053(1 - 5/RWR)
Brine Radium Concentration, pCi/1 = RWR
when a = 48.9, b = 2.84 for TDS = 2000 mg/1
and a = 120.5, b = 6.99 for TDS <_ 1000 mg/1
These expressions are plotted in Figure 45.
1 - 0.95
RWR
a + b RWR
(Eq. 29)
99
-------
o
o
Q.
>
-\
_Q
ro
a:
ai
4->
03
-a
a>
Ul
c
O)
c:
CO
.30
.25
.20
.15
.10
.05
.00
IDS ~ 1000
10
15
20
25
30
35
40
45
50
55
60
Raw Water Radium, pCi/1
FIGURE 44, BRINE TO FINISHED WATER, REVERSE OSMOSIS.
-------
600r-
Raw Water Radium, pCi/1
FIGURE 45. RADIUM CONCENTRATION IN BRINE, REVERSE OSMOSIS.
-------
TABLE 13. BRINE VOLUMES IN REVERSE OSMOSIS
Total
Dissolved
Solids
mg/1
2000
2000
2000
1000
1000
1000
400
400
400
Raw
Water
Radium
pCi/1
7.5
20
50
7.5
20
50
7.4
20
50
Treated
Fraction
fl
0.351
0.789
0.947
0.351
0.789
0.947
0.351
0.789
0.947
Brine
to
Product
Ratio
0.271
0.271
0.271
0.110
0.110
0.110
0.110
0.110
0.110
Brine
to
Finished Water
Ratio
0.0951
0.214
0.257
0.0386
0.0868
0.1042
0.386
0.0868
0.1042
Raw
to
Finished Water
Ratio
1.0951
1.214
1.257
1.0386
1.0868
1.1042
1.0386
1.0868
1.1042
BRINE DISPOSAL
Problems in disposal of brines from a reverse osmosis plant are similar
to those discussed previously for an ion exchange plant. However, for every
unit of hardness removed more water is required by the reverse osmosis plant
and therefore the concentration of salt is less than for an ion exchange plant
and the volume is much greater. The water pollution control requirement may
be somewhat lessened due to these characteristics, but the wastewater contain-
ing elevated levels of radium may face the same public sensitivity.
The flow of wastewater from a reverse osmosis plant is more constant with
time. The reject stream may contain about three times the total solids in the
original feed.
Disposal techniques may often be limited by considerations of salinity
rather than radium concentration. The list of potential alternatives for
handling the wastewater streams is similar to ion exchange except that utili-
zation of the brine is not feasible. Possible alternatives are:
I. Discharge
A. To sanitary sewer
B. To local receiving water
II. Storage
A. Evaporation lagoons
B. Land spreading
102
-------
III. Disposal
A. Deep aquifers
B. Oil well fields
C. As nuclear wastes
Discharge to Sewers
Shunting the wastewaters to sanitary sewers taxes the biological process
of the waste treatment plant. In addition, the volume of wastewater to be
handled is more significant than for ion exchange plants and the salinity
added to the system will be eventually added to the receiving watercourse.
However, there will be some dilution (100 gpcd of sewage) and some fractiona-
tion into the digested sludge. The latter phenomenon may produce a sludge
that is unsuited for many of the normal uses of sewage sludge.
Discharge to Watercourse
Release of the wastewater brines from reverse osmosis plants may present
more significant problems from salinity than from a radiological considera-
tion. The following discussion concentrates on the radioactivity aspects.
If the background radium concentration in rivers is neglected, a simple
balance shows that limited dilution is necessary:
FLOW ~ [(Pop., millions)(113)(RWR)2]/(a + b RWR) (Eq. 30)
where FLOW is the river water flow in MGD necessary to dilute the effluent to
a radium level of 5 pCi/1. The expression for various population ranges is
graphically presented in Figure 46. Note that, even at a high radium level
in the raw water and a population of 50,000, the required flow is less than
100 MGD.
If salinity and water quality standards are still incompatible, con-
trolled dilution may be considered. Holding lagoons will serve the purpose of
allowing discharge at seasonally higher or other daily increases in stream-
flow. Costs, other than transportation, should be less than $0.02/1000
gallons.
Ocean outfalls are applicable to only a limited area since transportation
costs rise rapidly with distance.
Evaporation Lagoons
Evaporation ponds may afford an effective method of brine disposal if the
following conditions exist: (1) the net evaporation rate (gross annual evapo-
ration minus annual rainfall) exceeds approximately 40 in. per year; (2) the
net evaporation occurs at a uniform rate throughout the year; and (3) the
103
-------
1000.0
g 100.0
o
x
Q
OO
s-
Ol
>
fV
o>
i-
CT
d)
10.0
1.0
0.1
0.05
100.0
10.0
OO
u_
CJ
1.0
-a
HI
cr
OJ
0.1
0.01
0.050
6.0
15.0
25.0 35.0
Raw Water Radium, pCi/1
45.0
55.0
FIGURE 46. RIVER WATER FLOW REQUIRED TO DILUTE REVERSE OSMOSIS BRINE TO 5.0 pCi/1
-------
impounded water is kept at shallow depths. These conditions are determined
for fresh water. Since the effect of salinity increase in brine disposal
ponds will reduce the rate of evaporation, disposal ponds must be designed
to account for the difference in evaporation rate between fresh and saline
water.
Acreage required for reverse osmosis plants will greatly exceed those
needed for ion exchange plants. Additional discussion of lagoon features is
found under the ion exchange section.
Landspreading
Discharge of reverse osmosis brine wastes onto large land areas can be
expected to create serious problems with cover vegetation. Although the land
may serve to "absorb" large quantities of the salt before contamination of the
ground water is expected, the land may be permanently relegated for no other
use. Landspreading does not appear to be a viable disposal alternative.
Brine Injection Wells
Brine wells for injection into deep aquifers may provide a means of dis-
posing of the spent brine. The volumes to be handled greatly exceed those
in the ion exchange brine problem. The lower salinity may negate the necessity
for conditioning before injection into the formations. Radium levels are of
no concern to the design however, this method represents a highly desirable
procedure for the radium disposal. More sites may be suitable at the lower
salinity. More detailed discussions of subsurface injection has been given in
the ion exchange section.
Treatment as a Nuclear Waste
Evaporators of the general type used in nuclear plants, but without the
offgas clearings and radiological monitoring features could be used to obtain
a sludge suitable for fixation, containment, shipment and burial. The evapo-
ration cost may be expected to exceed $30.00/1000 gallons of brine or about
$6.00/1000 gallons of water treated.
COST OF REVERSE OSMOSIS SOFTENING
Figure 47 presents the capital cost of reverse osmosis systems designed
to reduce radium in the finished water to the limit of 5.0 pCi/1. Figure 48
presents the annual operating and maintenance costs for reverse osmosis treat-
ment. Both cost curves are shown as a function of raw water radium and plant
capacity only.
The range of raw water TDS investigated in this report is 400 - 2000 mg/1,
and very little cost data is available for reverse osmosis treatment of low
solids raw water. The costs presented are for low brackish waters <4000 mg/1
TDS.
105
-------
1,000
o
o
o
X
o
o
n_
fC
o
100
10
RWR
0.01
I I I I I I I I I
0.1 1.0
Plant Capacity, MGD
• i I
10
0.1
Plant Capacity, m^/Day
10
FIGURE 47- CAPITAL COSTS OF REVERSE OSMOSIS TREATMENT
20
106
-------
1,000
o
o
o
i/i
O
O
-------
BRINE DISPOSAL COSTS
Several methods for brine disposal were considered for detailed calcula-
tions: lined evaporating ponds, pipeline and transmission, subsurface injec-
tion, and treatment as a nuclear waste. Assumptions and curves follow.
Costs of brine disposal by lined evaporating ponds assumed a net evapo-
ration of five feet per year26 and a land cost of $1850 per acre. Capital
costs included land, construction, vinyl lining, engineering design, and con-
tingency. Operation and maintenance costs included all labor, including pay-
roll extras and overhead, as well as supplies and repair of equipment. Figure
49 summarized the unit costs for different radium concentrations and total
dissolved solids.
Costs of brine transmission to an outfall assumed one mile of pipeline
and one pumping station.26 Outfall costs were considered negligible. Capital
costs included pipeline, pumping station, and right-of-way costs. Operating
and maintenance costs included power labor and overhead. Figure 50 summarized
the final unit costs as a function of radium concentration and total dissolved
solids.
Subsurface injection costs were calculated with basic assumptions26 of
3000 ft depth, well head pressure of 500 psi, an aquifer permeability of 135
millidarcies, and a porosity of 5 percent. Capital costs included wells, well
field distribution system, pumping station, storage, engineering and design,
interest during construction, and contingency. Not included were environmental
impact assessments required by many states. Operation and maintenance costs
included power, supplies, labor and overhead. Figure 51 indicates the unit
costs for different radium concentrations and total dissolved solids.
108
-------
oo
E
•be-
o
o
1.0 —
0.10
0.01
0.005 L.
1.00
•S
o
o
o
I/)
SO. 10
0.01
RWR = 50 pCi/1
O -O O RWR = 20 pCi/1
RWR =7.5 pCi/1
.il
t i i
...I
i i i i i
i i i
0.01
0.10
1.0
10
50
0.
20
TOO
Plant Capacity, m /day
FIGURE 49. UNIT COST OF WASTE DISPOSAL BY LINED EVAPORATING PONDS, REVERSE OSMOSIS
-------
1.00
1.00
CO
E
CO
o
-t->
c
01
o
§ 0.10
co
o
o
0.10
o.oiL
0.01
I I I I I I I I
I II I I I I I
RWR
RHR
RWR - 50 pCi/1
= 20 pCi/1
=7.5 pCi/1
0.01
0.10 1.0
Plant Capacity, MGD
I
IDS 2000
i i i i i i i I
10
I
°~ 1 10 20
Plant Capacity, 1000/m3/day
FIGURE 50. UNIT COST OF WASTE BRINE TRANSMISSION PER MILE OF PIPELINE, REVERSE OSMOSIS
-------
1.00 r-
0.10
c/)
O
O
.01
.005
1.00
rO
CJ>
-O
O
O
in
O
• 0.10
0.01
RWR = 50 pCi/1
RWR = 20 pCi/1
RWR =7.5 pCi/1
i i i i i i 111 i i i i i i i 11 i i i i i i 111
0.01
IDS 2000
IDS 2000
IDS 1000
IDS 2000
IDS 1000
IDS 1000
0.10
1.0
Plant Capacity, MGD
10
0.1
10 20
Plant Capacity, 1000 m3/day
100
FIGURE 51. UNIT COST OF WASTE DISPOSAL BY SUBSURFACE INJECTION: REVERSE OSMOSIS
-------
SECTION IX
UNIT COST CURVES
Unit cost curves for each process have been developed as a function of
raw water radium activity and total solids. Unit cost curves for RWR = 7.5
pCi/1, RWR = 20 pCi/1, and RWR = 50 pCi/1 are presented respectively in
Figures 52 through 54. These curves are based on the following conditions:
40-year plant life (20 years for ion exchange and reverse osmosis)
8 percent interest rate
These curves are intended for use as a preliminary estimate only. Any condi-
tions different from the above listed conditions or those conditions listed in
the cost determination section will materially affect these curves. It can be
seen from these figures that the ion exchange process offers the lower unit
cost of water treated to remove radium to the 5.0 pCi/1 limit, except at high
solids levels when the RWR is 20 or greater. The lime-soda process offers the
lower unit cost under these conditions.
The lime-soda process is quite cost effective for the entire range of
conditions, particularly for plant capacities over 10 MGD.
Reverse osmosis offers the highest unit cost. It is expected that
reverse osmosis will be limited to applications in which the raw water quality
is quite brackish or where the RWR is quite high.
112
-------
1.0
ro
E
, 0.1
0.01
0.005
ro
en
O
o
O
CO
o
o
1.0
0.1
0.01
'X X— All IDS
IDS
-4 41000
"-•4
""•* 400
2000
1000
400
-X Reverse Osmosis
Lime-Soda; Horizontal
Lime-Soda; Upflow
. . . Ion Exchange
A A —
l i i 11
....i
0.01
0.1
1.0
Plant Capacity, MGD
10
100
2000
1000
400
0.1
1.0
10
100
Plant Capacity, mj/day X 1000
FIGURE 52. COMPARISON OF UNIT COSTS OF WATER TREATMENT, WASTE DISPOSAL COSTS EXCLUDED, TO MEET
RADIUM STANDARD OF 5.0 pCi/1 FOR RWR = 7.5 pCi/1.
1000
-------
1.0 „
1.0
^0.1
ra
en
o
o
o
4->
O
o.i
0.01
0.005
0.01
•A —
IDS
•- 2000
1000 2000
400 1000
400
Reverse Osmosis
Lime-Soda, Horizontal
Lime-Soda, Upflow
A—A—1
i_ Ion Exchange
,1
. ....I
0.01
0.1
1.0
Plant Capacity, MGD
10
100
100
0.1 1.0 10
Plant Capacity, m3/day X 1000
FIGURE 53. COMPARISON OF UNIT COSTS OF WATER TREATMENT, WASTE DISPOSAL COSTS EXCLUDED, TO McET RADIUM
STANDARD OF 5.0 pCi/1 FOR RWR = 20 pCi/1.
1000
-------
1.0 r
ro
E
to
J0.1
O
O
0.01
0.005
1.0
rd
CD
O
O
O
O
CJ>
= 0.1
0.01
c- 400
2000
1000
400
-X Reverse Osmosis
— Lime-Soda, Horizontal
Lime-Soda, Upflow
±_ Ion Exchange
LlL
i i
...I
0.01
0.1
1.0
Plant Capacity,
10
100
MGD
0.1
FIGURE 54.
1.0 10
Plant Capacity, m3/day X 1000
100
1000
COMPARISON OF UNIT COSTS OF WATER TREATMENT, WASTE DISPOSAL COSTS EXCLUDED, TO MEET
RADIUM STANDARD OF 5.0 pCi/1 FOR RWR = 50 pCi/1.
-------
SECTION X
REFERENCES
1. Cember, Herman. Introduction to Health Physics, Pergamon, 1969.
2. Hursh, John B., "Radium Content of Public Water Supplies," JAWWA,
January 1954.
3. Statement of Basis and Purpose for the Proposed National Interim
Primary Drinking Water Regulations, Radiactivity. U.S. Environmental
Protection Agency, August 15, 1975, pp. 64-67.
4. Ibid 3, p. 14.
5. Petersen, Norman J., Samuels, Larry D., M.D., Lucus, Henry F. and
Abrahams, Simon P., M.D., "An Epidemiological Approach to Low-Level
Radium-226 Expsoure," Public Health Reports, 81 (0): 805-814,
September 1966.
6. Ibid 3.
7- "Standards for Protection Against Radiation" Title 10, Part 20,
Code of Federal Regulations, revised as of January 1, 1963, pp. 96-118.
8. "A Manual for Evaluating Public Health Service Drinking Water
Standards, 1962." PHS Publication 956, 1962.
9. Interim Primary Drinking Water Regulations, Radiactivity, U.S.
Environmental Protection Agency (40 CFR Part 141), Federal Register,
July 9, 1976.
10. Radiochemical Methodology for Drinking Water Regulations, U.S.
Environmental Protection Agency Publication. EPA 600/4-75-005, Sept.
1975.
11. "Determination of Radium Removal Efficiencies in Iowa Water Supply
Treatment Processes," Technical Note ORP/TAD-76-1, Office of
Radiation Programs, U.S.E.P.A., June 1976.
12. "Determination of Radium Removal Efficiencies in Illinois Water Supply
Treatment Processes," Technical Note ORP/TAD-76-2, Office of Radiation
Programs, U.S.E.P.A., May, 1976.
116
-------
13. "Monograph of the Effectiveness and Cost of Water Treatment
Processes for the Removal of Specific Contaminants, Vol. I, Technical
Manual, prepared for the EPA Office of Air and Water Programs by
David Volkert and Associates, August 1974.
14. Dye, John F., and Tuepker, J.L. "Chemistry of the Lime-Soda Process,"
from Water Quality and Treatment, published by the AWWA, 1971.
15. Ibid 14.
16. "Waste Sludge and Filter Washwater Disposal from Water Softening
Plants," prepared for the Ohio Department of Health by Burgess and
Niple, Ltd., 1969.
17. Fulton, George P., "Water Plant Waste Treatment: State of the Art,
Part Two, Public Works, February 1976.
18. Process Design Manual for Sludge Treatment and Disposal, Environ-
mental Protection Agency, Technology Transfer, October 1974.
19. Ibid 18.
20. Ibid 18.
21. Ibid 18.
22. Ibid 18.
23. Bowers, Eugene, "Ion Exchange Softening," from Water Quality and
Treatment, AWWA, 1971.
24. Riehl, Merril L., Water Supply and Treatment, National Lime Associa-
tion, Washington, 1970.
25. "Water Management," Powers Magazine, McGraw Hill, January 1966.
26. Desalting Cost Calculating Procedures, Research and Development
Progress Report No. 555, prepared for the Office of Saline
Water, U.S. Dept. of Interior, May 1970.
27. Buckley, John D. "Reverse Osmosis: Moving from Theory to Practice,"
Consulting Engineer, November 1975.
28. Ibid 27.
117
-------
APPENDIX A
118
-------
ANNUAL COST SHEET
PROJECT :
PROJECT DESCRIPTION:
K. ANNUAL OPERATING COSTS:
O&M LABOR, SUPPLIES &
MAINTENANCE MATERIAL
8.
9.
10.
11.
FUEL
12.
13.
STEAM
14.
15.
ELECTRIC POWER
16.
CHEMICALS
17.
ANNUAL REPLACEMENT COSTS
18.
OTHER ANNUAL COSTS
19.
ESTIMATED
COST
COST
INDEX
L. TOTAL ANNUAL COSTS
M. DEPRECIATING CAPITAL COST
(ANNUAL BASIS)
N. NON-DEPRECIATING CAPITAL
(ANNUAL BASIS)
0. TOTAL ANNUAL CAPITAL CHARGES
P. TOTAL ANNUAL COSTS (SUM ITEM
Q. COST OF WATER ($/m2)
S L, 0)
CURRENT
ESTIMATED COST
119
-------
CAPITAL COST SHEET
PROJECT:
PROJECT DESCRIPTION:
DATE:
PRICE LEVEL:
PLANT CAPACITY:
ANNUAL PRODUCTION:
INTEREST RATE:
PLANT LIFE:
WATER SUPPLY CHARACTERISTICS:
PRODUCT WATER CHARACTERISTICS:
CAPITAL COST CENTERS:
ESTIMATED
COST
COST
INDEX
CURRENT
ESTIMATED COST
1.
2.
3.
B. SUBTOTAL
C. INTEREST DURING
CONSTRUCTION
D. START-UP COSTS
E. OWNERS GENERAL EXPENSE ___ ~
F. TOTAL DEPRECIATING CAPITAL
G. LAND COSTS
H. WORKING CAPITAL
I. TOTAL NON-DEPRECIATING COSTS
J. TOTAL CAPITAL COSTS
su
120
-------
COMPUTATION SHEET
PROJECT:
PROJECT DESCRIPTION:
ANNUAL FUEL COSTS:
ANNUAL STEAM COSTS:
ANNUAL POWER COSTS:
ANNUAL REPLACEMENT COSTS:
ANNUAL CHEMICAL COSTS:
LAND REQUIREMENTS:
OTHER COMPUTATIONS:
121
-------
APPENDIX B
SAMPLE CALCULATIONS
Lime-Soda Process
High Solids Raw Water
TH - 750 mg/1 @ CaC03
Ca4"4" - 500 mg/1 @ CaC03
Mg++ - 250 mg/1 @ CaC03
ALK - 300 mg/1 @ CaC03
IDS - 2000 mg/1
C02 - 11.4 mg/1 @ CaC03
1 - Desired finished water for Rao =7.5 pCi/1
Ra removal required - 33 percent or .33
TH removal required - Ra2'86
rem
= .332'86 = .042
Minimum TH considered practical in lime-soda process is 35 percent
TH removal required - .35 (750) = 262 mg/1 @ CaC03, or 5.25 mg/1
TH of finished water= 488 mg/1 @ CaC03 or 9.75 mg/1
2 - Chemical requirements
Parameter
C02
Ca++
Mg4^
HC03
TOTALS
mg/1
5
200
60
366
Raw
mg/1
0.23
10.00
5.00
6.00
Finished
meq/1
0
4.75
5.00
0
A
mg/1
0.23
5.23
0
6.00
Required
CaO
meq/1
0.23
5.25
—
0.75
6.23
Required
CaO
meq/1
-
-
-
Lime Required =
_ (6.23)(28) _
.90
= 194 mg/1
Soda Ash Required = None
122
-------
CAPITAL COST SHEET
PROJECT:
Lime-Soda Softening Plant 3.0 MGD (11,360 m /Day)
PROJECT DESCRIPTION:
Conventional Plant with
Rapid Sand Filtration
DATE:
PRICE LEVEL:October 1, 1975-
PLANT CAPACITY:3.0 MGD (11350m /day)
3
ANNUAL PRODUCTION:^, 145,000 m
INTEREST RATE:_
PLANT LIFE:
8%
40 yrs.
WATER SUPPLY CHARACTERISTICS:
RaQ = 7.5 pCi/1
High Solids
PRODUCT WATER CHARACTERISTICS
A. CAPITAL COST CENTERS:
Source: David Volkert & Assoc.
ESTIMATED
COST
COST
INDEX
CURRENT
ESTIMATED COST
-*-• Plant Construction (Basins)
$330,000
1351/1137
$ 392,100
2-Plant Construction (Filters)
$300,000
1351/1137
356,500
3-Site Development (Basins)
$250,000
1351/1154
292,700
4. Site Development (Filters)
$ 70,000
1351/1154
81,950
5.
6.
7.
B .
C.
D.
E.
F.
G.
H.
I.
J.
SUBTOTAL
INTEREST DURING CONSTRUCTION-^-^-- @--&I
START-UP COSTS ----------- _Ul2--af— L
OWNERS GENERAL EXPENSE—-1-2^--9—-?
TOTAL DEPRECIATING CAPITAL (SUM B, C, D,
LAND COSTS ------------------------------
WORKING CAPITAL --------- l/_6__qf__L ---------
TOTAL NON-DEPRECIATING COSTS ------------
TOTAL CAPITAL COSTS ---------------------
E)-
$1,123,250
89,900
16,275
134,800
$1,364,200
4,200
32,600
36,800
$1,401,000
123
-------
ANNUAL COST SHEET
PROJECT :
Lime-Soda Softening Plant 3.0 MGD (11,360 CMD)
Ra0 = 7.5
PROJECT DESCRIPTION: Conventional Plant with Rapid Sand Filters ; E±gh Solids
K. ANNUAL OPERATING COSTS: *
O&M LABOR, SUPPLIES &
MAINTENANCE MATERIAL
8. Labor and Other O&M Costs
9.
10.
11.
FUEL
12. N/A
13.
STEAM
14. N/A
15.
ELECTRIC POWER
16. N/A
CHEMICALS
17 . Lime
ANNUAL REPLACEMENT COSTS
18. N/A
OTHER ANNUAL COSTS
19. N/A
ESTIMATED
COST
$42,300
COST
INDEX
L. TOTAL ANNUAL COSTS
M. DEPRECIATING CAPITAL COST
(ANNUAL BASIS) 0.0839 (1,364,200)
N. NON-DEPRECIATING CAPITAL
(ANNUAL BASIS) 0.08 (36,800)
0. TOTAL ANNUAL CAPITAL CHARGES
P. TOTAL ANNUAL COSTS (SUM ITEM
Q. COST OF WATER ($/m2) 312,800
^Source: Compilation of Personal
3 L, 0)
CURRENT
ESTIMATED COST
$153,000
$42,300
$195,300
114,500
3,000
117,500
$312,800
4- 4,145,000 cm = $.075/m3 or $.286/1000 gal
Correspondence of Authors
124
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APPENDIX C
I >.. Exchange
1 - Mass Balance Calculation
To determine fraction of raw water influent blended, and fraction treated,
assuming 95 percent reir aval in I/E or R/D column.
For mass balance of Ra:
.05 Ra0x + Ra0 (1-x) = (1)(5)
.05 Ra0x + RaQ - Raox = 5
x RaQ (.05 - 1) + Ra0 = 5
-.95 x Ra0 = 5 - Rao
= 5-Ra0
X -.05 Ra0
x = Ra0 - 5
.95 Ra0
Blending allowed to attain minimum level of 5 pCi/1 Ra assuming 95 per-
cent Ra removal in I/E and R/0
Ra Level Fraction Blended Fraction Blended
50 .053 .947
20 .211 .789
7.5 .649 .351
2 - Regenerant Chemicals Calculations
Assume: 1) operating capacity of resin = 20 kgr hardness as CaCOg/CF
2) regeneration is with a 10 percent brine concentration
3) salt required for regeneration is 0.30 Ib salt/kgr hardness
as CaCo3 removed (6 Ib salt/CF)
4) 95 percent TH removal in unit (5 percent leakage)
125
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Solids Levels:
High - TH = 750, TH_ = .05 (750) = 37.5
—°— raw F
TH = 712.5 mg/1
rem
Kilograins hardness removed
712. 5 mg/1 1 grain/gal k kgr _ kpr/pal
17.1 mg/1 1000 g ~ tim/ k§r/§al
Salt regeneration requirement/MG
.0417 x 106 kgr .30 lb salt =
mg kgr
Volume of rinse water/MG, assume 30 gal/CF resin
41,700 kgrTHr CF 30 gal _ ,„
mg 20 kgr CF ' gal
Volume of regeneration brine solution/MG
- 12,510 = 112,590 lb H20
13,500 gal H20
Total volume of backwash + rinse water/MG
High Solids - 13,500 + 62,550 = 76,050 gal or 7.6 percent of total flow
126
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COMPUTATION SHEET
PROJECT:
Lime-Soda Softening Plant 3.0 MGD (11,360 CMD)
PROJECT DESCRIPTION:
Conventional Plant with Rapid Sand Filters
Ra = 7.5 High Solids
ANNUAL FUEL COSTS:
Included in Line 8
ANNUAL STEAM COSTS:
Included in Line 8
ANNUAL POWER COSTS:
Included in Line 8
ANNUAL REPLACEMENT COSTS:
Included in Line 8
ANNUAL CHEMICAL COSTS:
Lime -
1610 Ib
MG
3 MG
Day
365 Days
yr
Ton
2000 Ib
$45
Ton
LAND REQUIREMENTS:
5 ha @ $750 = $3750
Mixers and Basins . 5 ha @ $750 = 375
$4125 say $4200
OTHER COMPUTATIONS:
127
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ANNUAL COST SHEET
PROJECT:
Ion Exchange
0.5 MGD
PROJECT DESCRIPTION:
Ra0 = 7.5
TDS = 400
K. ANNUAL OPERATING COSTS:
ESTIMATED
COST
COST
INDEX
CURRENT
ESTIMATED COST
O&M LABOR, SUPPLIES &
MAINTENANCE MATERIAL
8 . Overhead and Maintenance
$13,000
7.28/6.25
$15,100
9.
10.
11.
FUEL
12.
13.
STEAM
14.
15.
ELECTRIC POWER
16.
CHEMICALS
17.
$3,200
$3,200
ANNUAL REPLACEMENT COSTS
18.
OTHER ANNUAL COSTS
19.
L. TOTAL ANNUAL COSTS
M. DEPRECIATING CAPITAL COST
(ANNUAL BASIS)__JJ3J^_(X5_2_J30_QJ_
N. NON-DEPRECIATING CAPITAL
(ANNUAL BASIS) _jj!8__(_l_7_0-0)
0. TOTAL ANNUAL CAPITAL CHARGES
P. TOTAL ANNUAL COSTS (SUM ITEMS L, 0)__
Q. COST OF WATER ($/m2) $33,900/690,800
$18,300
15,500
100
15,600
33,900
m3 = $.049/m3 or .186/1000 gal.
128
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CAPITAL COST SHEET
PROJECT:
Ion Exchange 0.5 MGD (1892 m3/day)
PROJECT DESCRIPTION:
DATE:
Actual Treated Flow = 667 m3/day
PRICE LEVEL: October 1975
PLANT CAPACITY: 0-5 MGD (1892 m3/day)
ANNUAL PRODUCTION: 690,800 m3
INTEREST RATE: 8 percent
PLANT LIFE: 20 years
WATER SUPPLY CHARACTERISTICS:
Ra0 - 7.5
TDS - 400
PRODUCT WATER CHARACTERISTICS:
A.
1.
2.
CAPITAL COST CENTERS:
Source: David Volkert & Assoc.
Plant Construction
Site Preparation
3.
4.
5.
6.
7-
B.
C.
D.
E.
F.
G.
H.
I.
J.
ESTIMATED
COST
$73,000
$37,000
COST
INDEX
1351/1137
1351/1154
SUBTOTAL
INTEREST DURING
CONSTRUCTION 6 mos @ 8%_p_er_year = 4% of B
START-UP COSTS 1/12 x item L
OWNERS GENERAL EXPENSE 12 percent of B
TOTAL DEPRECIATING CAPITAL (SUM B, C, D,
LAND COSTS 125 ha @ $750 =
E)
WORKING CAPITAL
TOTAL NON-DEPRECIATING COSTS
TOTAL CAPITAL COSTS
CURRENT
ESTIMATED COST
$86,700
$43,300
$130,000
5,200
1,500
15,600
152,300
200
1,500
1,700
$154,000
129
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APPENDIX D
Reverse Osmosis Calculations
1 - Assumptions
High Solids - Initial TDSi = 2000 mg/1
Product TDSi = -05 (2000) = 100 mg/1
Calcium initial, Ca-L = 200 mg/1
2 - Brine to Product Ratio (BPR) =
_ 1 - (TDSp/TDSj)
(900/Cai) - 1
= 1 - (100/2000) _ ^95_ _
(900/200) - 1 3.5 ~ ' '
3 - Brine Volume
= Vp x BPR = .271 Vp Vp = Product Volume
4 - Feed Volume
= Vp + ,271 Vp = 1.271 Vp
130
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CAPITAL COST SHEET
PROJECT :
Reverse Osmosis
PROJECT DESCRIPTION:
Actual Treated Flow
3
667 m /day
0.5 MGD (1892 m3/day)
DATE:
PRICE LEVEL: October 1975
PLANT CAPACITY: 0.5 MGD, 1892 m3/day
ANNUAL PRODUCTION: 690,800 m3
INTEREST RATE: 8 percent
PLANT LIFE: 20 years
WATER SUPPLY CHARACTERISTICS:
Ra0 7.5; TDS 400
PRODUCT WATER CHARACTERISTICS:
A. CAPITAL COST CENTERS:
Source: David Volkert & Assoc.
•*•• Plant Construction
2. Site Development
3.
4.
5.
6.
7.
B . SUBTOTAL
ESTIMATED COST
COST INDEX
$185,000 1351/1137
38,000 1351/1154
C. INTEREST DURING
CONSTRUCTION
D. START-UP COSTS
E. OWNERS GENERAL EXPENSE
F. TOTAL DEPRECIATING CAPITAL (SUM B, C, D, E)
G. LAND COSTS negligible
H. WORKING CAPITAL
I. TOTAL NON-DEPRECIATING COSTS
J. TOTAL CAPITAL COSTS
CURRENT
ESTIMATED COST
$220,000
44,000
$264,000
11,000
8,000
32,000
315,000
—
8,000
8,000
$323,000
131
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ANNUAL COST SHEET
PROJECT : o ,
Reverse Osmosis 0.5 MGD (1892 nrVday)
Ra ~ 7 5
PROJECT DESCRIPTION: TD§ = 450
K. ANNUAL OPERATING COSTS:
O&M LABOR, SUPPLIES &
MAINTENANCE MATERIAL
8.
9.
10.
11.
FUEL
12. *
13.
STEAM
14. *
15.
ELECTRIC POWER
16. *
CHEMICALS
17.*
ANNUAL REPLACEMENT COSTS
18. *
OTHER ANNUAL COSTS
19. *
ESTIMATED
COST
$12,000
COST
INDEX
7.28/6.25
L. TOTAL ANNUAL COSTS
M. DEPRECIATING CAPITAL COST
(ANNUAL BASIS) (.10185) (315,000)
N. NON-DEPRECIATING CAPITAL
(ANNUAL BASIS) -08 (8,000)
0. TOTAL ANNUAL CAPITAL CHARGES
P. TOTAL ANNUAL COSTS (SUM ITEM!
Q. COST OF WATER ($/m2) $133,0
*$125 per 1000m3 production cove
CURRENT
ESTIMATED COST
$14,000
$86,000*
$100,000
32,000
1,000
j 33,000
5 L, 0) $133,000
00/609,000 = $.218/m3 or $.826/1000 gal.
rs all items indicated.
132
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APPENDIX E
133
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In the main body of the report it was stressed that the reported costs of
treatment and waste disposal for removal of radium to the proposed interim
standard were for entirely new construction. Many water utilities have exist-
ing facilities which, with treatment process improvements and/or minor con-
struction of additional facilities, can effectively meet the radium standard.
As an illustrative example, let us assume that three water utilities
utilize a raw water with the same chemical characteristics as the medium
solids water described earlier in this report. The chemical quality of this
water is then:
IDS 1,000 mg/1
TH 300 mg/1 as CaC03
Ca*4" 200 mg/1 as CaC03
Mg++ 100 mg/1 as CaC03
Alk 200 mg/1 as
Let us assume further that the radium level of the raw water is 50 pCi/1
and that all three plants have a design capacity of 3.0 MGD.
The three water plants have the following existing facilities:
Plant A - Chlorination only
Plant B - Conventional horizontal flow lime softening unit followed
by rapid sand filtration. Lime (CaCO) is used without soda
ash at a dose of 125 mg/1 resulting in a finished water TH
of 100 mg/1
Plant C - Ion exchange softening and blending of 30 percent raw
water to obtain a finished water TH of 100 mg/1 as CaC03
In order for utility A to meet the proposed interim standard of 5.0 pCi/1
entirely new treatment facilities must be constructed and the cost to the
utility would be that obtained from the cost curves presented in this report
and summarized below:
Utility A decides to construct an upflow solids contact lime-soda soft-
ening unit with rapid sand filtration.
Capital costs are estimated from Figure 4 to be $1,000,000.
Annual operating costs are estimated from Figure 14 to be $200,000 per
year .
Unit costs of treatment are estimated from Figure 54 to be approximately
$.30/1000 gallons.
Sludge disposal will be handled by a temporary sludge thickening lagoon
at a unit cost of $.01/1000 gal from page 52 followed by transportation
by truck to a nearby landfill at a unit cost of approximately $.02/1000
gal for transport from Figure 17 and $.15/1000 gal for landfilling the
thickened sludge from Figure 19.
Total unit cost of the new system is then:
134
-------
Treatment $.30/1000 gallons
Disposal $.18/1000 gallons
Total $.48/1000 gallons
Utility B is presently removing 66 percent of raw water TH. The actual
amount of radium removal should be determined by radiochemical analysis,
but for illustrative purposes Figure 3 can be used to estimate the fin-
ished water radium level at 6.8 pCi/1. In order to remove radium to 5
pCi/1, 90 percent of RWR must be removed corresponding 74 percent TH
removal (also from Figure 3). The finished water TH must be equal to or
less than 78 mg/1 as CaCC>3. This can be achieved by the addition of
approximately 55 mg/1 more lime and 55 mg/1 soda ash. Simple jar jests
can be used to verify required chemical doses estimated for additional
hardness removal. The additional chemical doses will cost the utility:
55 mg/1 CaO x 834 Ib/MG x 3 MGD x 365 days x $98 =
mg/1 Year 2000 lb~
$12,050/year Lime
55 mg/1 Na?C03 x 8.34 Ib/MG x 3 MGD x 365 days x $ 87 =
mg/1 year 200° lb
$21,849/year Na2C03
Total Annual- Additional Cost = $46,462
Total Unit Cost Addition = $.04/1000 gal
In order for Plant C to remove radium to 5 pCi/1, 94.7 percent of the
raw water must be treated, from Figure 24 or simple mass balance assuming 5
percent leakage of radium. Since the plant is currently treating only 70
percent of the raw water, the increase in treated water fraction amounts to
(.947 - .700)(3 MGD) = .74 MGD which must be treated.
Assuming that the present unit is operating at full design capacity, an
additional ion exchange unit (or units) must be added to handle the increase
in water to be treated. The design capacity of the additional units will then
be .75 MGD.
From Figure 31, the capital cost of plant expansion will be approximately
$470,000.
From Figure 34, the increased annual operating and maintenance costs will
be approximately $60,000 per year.
From Figure 54, the unit cost of the water produced by the additional
treatment facilities will be approximately $.37/1000 gallons, assuming that
135
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presently existing brine disposal facilities will be adequate. Assuming the
present unit cost of water treated by Plant C is $.15/1000 gallons, proportion-
ing the unit cost of the expanded facilities gives a new unit cost estimate of
$.21/1)00 gallons. The resulting increase in unit cost necessary to meet the
radium standard of 5.0 pCi/1 then is $.06/1000 gallons.
The above example demonstrates that three similar size utilites treating
similar water ranged from $.04/1000 gallons to $.48/1000 unit cost required
for meeting the radium standard of 5.0 pCi/1.
136
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APPENDIX F
1 . CALCULATIONS :
According to Burgess and Niple
14,000 gal of 4% sludge could be used per acre of Ohio farmland in order
to increase the pH of 5.9 to the desirable range. It has also been calculated
that 5 x 103 pCi/kg of Ra -226 can be obtained in 4% sludge (p ~ 1) .
14,000 gal/acre x 3.78 liter/gal = 53,000 liter/acre.
53,000 liter/acre x 5 x 103 pCi/liter = 2.65 x 108 pCi/acre
2.65 x 108 pCi/acre x X a"!f 2 - 6-05 x lo3 pCi/ft2
T" • -J / X J_vJ I L
Assuming a mixing depth of 6"
6.05 x 103 pCi/ft2 x 2 = 12.1 x 103 pCi/ft3 for the top 6'.'
Assuming no uptake by vegetation or weathering loss,
i 01 init n-/^3 1 ft3 = 4.27 x 102 pCi/liter
1.21 x 10* pCx/ft3 x 28 . 3 1±ter = 4-2? x 10-l pci/gm>
Now: .2 pCi/gm E> .0005 WL
WL)(. 427)
Y= .4
• fc-
Note: Correction factor (~ .4)
Therefore, in 25 years, you would exceed .01 WL in worst possible case.
However, this is only WL.
Worst possible case is that which would exist only if this quantity was
added to the site every year and there is no uptake by vegetation or weather
ing effects.
137
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2 . CALCULATIONS :
Using "EPA models" and in-house data we know the following:
(1) ~ 17 yR/hr (estimated a) .01 WL (internal structure)
(2) ~ 1.2 yR/hr (external a) .0002 WL
(3) 1 WL = 102 pCi/liter of Rm 10~2 WL = 103 pCi/m3 of Rn
(definition)
(4) cj> =1.6 CR _o. i-n soil pCi/m2 - sec where
(a) C oof: is cone, in pCi/gm;
(b) cj> is the radon flux from soil.
(5) C = 155 (assumption of EPA model)
Assume C 00, soil = 1 pCi/gm.
~
C = 155 cj) 155 x 1.6 pCi/m3 of Rn ~ 2.5 x 102 pCi/m3 Rn.
2.5 x 102 pCi/m3 x 10/pei/S Rn 2'5 X ^ ^
Thus 0.01 WL = 4 pCi/gm of Ra in soil.
Now 4 pCi/gm = 4 x 103 pCi/kg Highest 4% sludge radium concentration.
138
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-77-073
2.
4. TITLE ANDSUBTITLE
Costs of Radium Removal from Potable Water
7. AUTHOR(S)
J.E. Singley, B.A.
and J.F. Palmer
3. RECIPIENT'S ACCESSI Of* NO.
5. REPORT DATE
April 1977 (Issuing Date)
^U.FFJ_J.C;O g peRFoRMING ORGANIZATION CODE
8. PERFORMING ORGANIZATION REPORT NO.
Beaudet, W.E. Bolch
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Department of Environmental Engineering Sc
University of Florida, Gainesville, Floric
and
Water and Air Research, Inc., 6281 S.W. Ai
Gainesville, Florida 32602
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratoi
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
10. PROGRAM ELEMENT NO.
.iences 1CC614
•3 ° T 1 1
d j^.uj.j. 11. am^KKsar/GRANT NO.
cher Rd. EPA803864-01
13. TYPE OF REPORT AND PERIOD COVERED
y— Gin., OH Final Report
14. SPONSORING AGENCY CODE
EPA/600/14
15. SUPPLEMENTARY NOTES
16. ABSTRACT
This report presents the results of an analysis of existing data from various
sources on the removal of radium from potable water supplies by lime-soda soften-
ing, ion exchange, and reverse osmosis treatment methods. Removal efficiency
models are used to estimate the capital and annual operating and maintenance
costs for each water treatment process over a wide range of raw water quality,
raw water radium, and population conditions.
The radiological consequences of common methods of waste sludge and brine
disposal are discussed and waste volumes and activity levels of radium in waste
streams are estimated. The costs of ultimate disposal of the waste streams
produced by each process are estimated over the same raw water quality and popu-
lation ranges used to determine treatment costs.
This report is intended as a guide for planners and water utility personnel
in areas where the radium activity of potable water sources exceeds the limits
set by EPA Drinking Water Regulations.
17.
a. DESCRIPTORS
Radium
Water softening
Water treatment
Decontamination
Waste disposal
Cost estimates
Potable water
KEY WORDS AND DOCUMENT ANALYSIS
b. IDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Radium removal Iowa
Reverse osmosis Illinois J^B
Lime softening Florida
Ion exchange
Drinking water
Water treatment and
waste disposal costs
13. DI31 nlBUTION STATEMENT
Release to Public
19. SECURITY CLASS (This Report) 21. NO. OF PAGES
Unclassified 151
20. SECURITY CLASS (This page) 22. PRICE
Unclassified
EPA Form 2220-1 (9-73)
139
AUS GOVERNMENT PRINTING OFFICE. 1977—757-056/5569
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