TECHNICAL NOTE
ORP/TAD-76-5
THE UNITED STATES
ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RADIATION PROGRAMS
DECEMBER, 1976
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EPA REVIEW NOTICE
This report has been reviewed by the Office of Radiation Programs,
U.S. Environmental Protection Agency, and approved for publication.
Approval does not signify that the contents necessarily reflect the
views and policies of the U.S. Environmental Protection Agency, nor
does mention of trade names or commercial products constitute endorse-
ment or recommendation for use.
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PREFACE
The Office of Radiation Programs of the U.S. Environmental Protection
Agency carries out a national program designed to evaluate population
exposure to ionizing and non-ionizing radiation, and to promote development
of controls necessary to protect the public health and safety. This report
was prepared in order to summarize two extensive reports which examined the
natural radioactivity source terms associated with radium in water supplies
and the radium removal efficiencies of water treatment processes. Readers
of this report are encouraged to inform the Office of Radiation Programs of
any omissions or errors. Comments or requests for further information are
also invited.
David S. Smith
Director
Technology Assessment Division (AW-459)
Office of Radiation Programs
iii
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ABSTRACT
Numerous well-water supplies for public water systems contain naturally
occuring radium-226. Methods for removing radium from drinking water must
be identified so that drinking water treatment plants may meet the limit
set in the EPA drinking water regulations for radium in drinking water,
5 pCi/liter.
Studies were performed by State agencies at 14 cities in Iowa and Illinois
to determine the radium removal efficiency of four water treatment processes.
Populations served by the water treatment plants ranged from 235 to 25,000.
The radium-226 concentration in the raw water was greater than 5 pCi/liter
at 13 of the supplies and ranged from 3 to 49 pCi/liter.
Radium removal efficiencies at plants utilizing reverse osmosis and sodium
ion-exchange processes were generally about 92%. A much wider range of
removal efficiencies, 75% to 95%, was found at plants utilizing the lime-
soda ash softening process. Plants utilizing iron removal processes only
were found to have radium removals ranging from 11% to 53%.
Pilot plant studies at the USEPA Cincinnati laboratory indicated that radium
removal in the lime softening process is related to the pH used in the pro-
cess. Higher radium removal efficiency accompanies higher pH values.
It is concluded that water treatment processes are available for removing
radium from drinking water to meet the 5 pCi/liter limit.
iv
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TABLE OF CONTENTS
EPA Review Notice ii
Preface iii
Abstract iv
Table of Contents v
List of Figures vi
List of Tables vi
Conclusion 1
Introduction 2
Description of Study 3
Results 5
Reverse Osmosis 5
Iron and Manganese Removal 6
Sodium Cation Exchange 6
Lime-Soda Ash Softening 9
Pilot Plant 12
Summary of Results 17
References 18
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LIST OF FIGUEES
Figure No. Page No,
1 Radium Removal vs. Softening pH 14
LIST OF TABLES
Table No. Page No,
1 Cities Included in Radium Removal Studies 4
2 Ra-226 and Hardness Removals at Greenfield, Iowa
Reverse Osmosis Plant 5
3 Ra-226 and Iron Removals at Water Treatment Plants
Using Iron and Manganese Removal Processes 7
4 Ra-226, Iron and Manganese Removals by Iron and
Manganese Removal Processes 8
5 Ra-226 and Hardness Removals at Water Treatment Plants
Using Ion Exchange Processes 10
6 Ra-226 and Hardness Removals at Water Treatment Plants
Using Lime-Soda Ash Softening 13
7 Ra-226 Removal in EPA Lime-Softening Pilot Plant
Using Elgin, Illinois Water 16
8 Ra-226 Removal Efficiencies in Water Treatment Processes. . .17
VI
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CONCLUSION
A study to determine the efficiency of radium removal by conventional water
treatment processes indicates that reverse osmosis, ion-exchange and lime-
soda ash softening are effective in removing the major portion of the radium
from the water. High radium water was associated primarily with deep sand-
stone formations. The raw water radium concentrations ranged from 3 to 49
pCi/1 at the water treatment plants studied.
Overall removal of radium at a reverse osmosis plant was 96% as compared
with a concurrent hardness removal of 95% with a product water recovery
of 69%.
Radium-226 removals in the sodium cation exchange process were generally
above 90%, with the exception of Herscher, Illinois, where an 81% removal
was noted. At the latter plant, about 53% of the radium-226 was removed
in the aeration, settling and filtering pre-processing, before the ion ex-
change step. The data indicate that radium removal continues for a time
after the hardness removal capacity is exhausted; thus a simple analysis
for hardness may be used as an indicator when operating the plant for radium
removal. In all of the ion-exchange softener installations 6 to 25 percent
unsoftened water was bypassed around the softener and blended with the fin-
ished water being pumped to the distribution system to provide sufficient
calcium carbonate for deposition of a protective coating on the water mains.
Overall removal of radium-226 by softening and filtering at lime-soda ash
softening plants can reach 95%, dependent primarily on the pH of the process.
Considerable variations in radium removals were noted depending on chemical
dosage, pH range, magnesium removal, non-carbonate hardness removal and
filtration efficiency. Most of the removal efficiencies were found to fall
within the range of 75% to 96%.
Radium-226 extraction through iron removal units varied from 11% to 53%
using aeration, detention and filtration. The manner of radium removal is
possibly adsorption or catalytic action by the oxidation products (Fe(III)
and Mn(IV)) deposited on the filter media.
Relatively high concentrations of radium in waste waters and sludges must
be considered in determining the final disposal of these wastes. Currently,
such wastes are generally discharged to watercourses. An exception is the
discharge of lime sludge to evaporation lagoons in most instances. Addi-
tional research is needed to determine the most effective methods of waste
disposal.
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INTRODUCTION
Naturally occuring radium-226 is found in numerous well-waters. The U.S.
Environmental Protection Agency (EPA) published interim regulations on July
9, 1976, which limit the concentration of radionuclides in public water
systems (EN 76). Methods for removing radium had to be identified so that
drinking water treatment plants may be designed to meet the limit for com-
bined radium-226 and radium-228 of 5 pCi/liter.
Studies were performed by two State agencies, under EPA contracts, at 14
cities in Iowa and Illinois to determine the radium removal efficiency of
four water treatment processes; reverse osmosis, aeration and iron removal,
sodium cation exchange, and lime-soda ash softening (SC76 and BE76). This
work was supplemented by a study at the water treatment pilot plant located
in the EPA's Cincinnati laboratory.
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DESCRIPTION OF STUDY
Water supplies were selected for the study on the basis of (1) high raw
water gross alpha or radium-226 content (13 of the 14 supplies had radium-
226 concentrations greater than 5 pCi/1 in raw water), (2) a variety of
water treatment processes, (3) availability for continous operation during
the study and (4) a range of municipal populations served. A list of the
cities included in the study and some pertinent characteristics is shown
in Table 1.
Samples were collected from raw water supply wells and from points where
treated water enters the distribution system. In addition, treatment systems
in Iowa and at Herscher, Illinois, were sampled at various points throughout
the treatment processes to determine changes and removals of radium and
other pertinent chemical parameters. Flows and other data were obtained
to determine whether plants were meeting design rates and to provide data
for determining a material balance of radium-226 removals.
A significant difference between the two States' efforts was that, in Iowa,
each treatment system was sampled over the course of an operating cycle,
with numerous samples taken throughout the process whereas, in Illinois,
each system was sampled on each of three separate occasions at approximately
one-week intervals. Thus the results from Iowa give a detailed picture
of system operation, while the results from Illinois give an indication
of the variation of operating characteristics over a period of three weeks.
Samples of well water were generally collected near the beginning of a pump-
ing period and following longer pumping times to determine any time related
variability in radium, hardness and other chemical parameters during pumping.
Radium-226 analyses were performed in Iowa at the Iowa State Hygienic Labora-
tory using coprecipitation with mixed barium and lead sulfates in accordance
with Standard Method ASTM D 2460-70. Illinois radium-226 analyses were
performed by the Argonne National Laboratory using the radon emanation method.
Some samples were collected in duplicate for intra-laboratory collaborative
testing to check the accuracy of the radium-226 analysis.
The pilot plant in Cincinnati was used to investigate the removal of radium-
226 under ideal conditions of lime softening at two different pH levels,
9.5 and 10.6. The raw water was brought to Cincinnati by truck from the
Slade Avenue plant in Elgin, Illinois. Samples were collected of raw water,
treated water, and at two points in the treatment process, and were analyzed
using the radon emanation procedure by EPA in Cincinnati.
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TABLE 1
Cities Included in Radium Removal Studies
City
Plant Raw Water
Population Capacity Ra-226
Served (V/day) (pCi/1)
Remarks
Reverse Osmosis
Greenfield, Iowa
Iron Removal
Adair, Iowa
Stuart, Iowa
2212
750
1354
570
380
530
Ion Exchange
Dwight Correctional
Center, Illinois
Eldon, Iowa
Estherville, Iowa
Grinnell, Iowa
Herscher, Illinois
Holstein, Iowa
Lynwood, Illinois
Lime-Soda Ash Softening
Elgin, Illinois 25,000
Peru, Illinois 12,400
Webster City, Iowa 8488
West Des Moines,
Iowa 16,441
18,000
6830
5000
9730
14
13
16
235
1319
8108
8402
1000
1445
4000
110
360
3300
3790
380
590
600
3.3
49
5.7
6.7
14.3
13
14.7
5.6
6.0
7.8
9.3
Aeration & continuously
regenerated greensand filters
Aeration & pressure iron
removal filtration
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RESULTS
Reverse Osmosis
In the reverse osmosis demineralizing process the high hardness water is
pressurized and piped into a reverse osmosis unit where relatively pure
water diffuses through the semipermeable membrane and becomes the product
water, leaving a concentrated reject water. The much greater rejection
of divalent ions, such as Ca, Mg, Ra and 864, than the monovalent ions,
Na and Cl, is characteristic of essentially all reverse osmosis membranes.
The usual water supply for Greenfield, Iowa, is an impoundment of surface
water. A reserve source of water from a deep well is used during periods
of drought. The brackish well water, with a total solids content of more
than 2200 mg/1, is treated in a reverse osmosis unit installed in 1971.
A description of the plant and discussion of operating results was published
in 1972 (MO 72). Raw, product, and reject water samples were collected
and analyzed for radium-226 and other chemical constituents. The results
are shown in Table 2.
TABLE 2
Ra-226 and Hardness Removals at Greenfield, Iowa
Reverse Osmosis Water Treatment Plant
Sampling
Point
Well Supply
RO Plant Effluent
Ra-226
Percent
pCi/1 Removal
14
0.6 96
Hardness
mg/1 Percent
as CaCO^ Removal
610
29
95
The average radium-226 concentration in the reject water was 43 pCi/1, where
31% of the influent water was rejected and 69% was converted to low hardness
product water.
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Iron and Manganese Removal
The presence of iron and manganese in drinking water is objectionable pri-
marily because of taste and the precipitation of these metals turns the
water a turbid yellow-brown color. The treatment processes employed in
the removal or control of iron and manganese include:
1. Precipitation and filtration
a. Aeration, detention (or sedimentation) and filtration
b. Oxidation by potassium permanganate, chlorine or chlorine dioxide
2. Ion exchange
a. Continuously regenerated permanganate greensand filter
Iron and manganese removal is utilized in some form of pretreatment at five
ion-exchange softening plants and as the only removal process at two other
plants selected for study. The results are shown on Table 3.
A tabulation of radium removal, iron removal, manganese removal and pH (Table
4) suggests that radium-226 is being removed on the manganese, just as Mn-
impregnated fibers have been reported to remove radium (MO 75). There are
radium-226 removals of 46-56% when there is a significant manganese removal.
Fair (FA 68) notes that "Hydrous oxides of Fe(XTT) and Mn(IV) have high
sorption capacities for bivalent metal ions." Also, "Sorption capacities
for Mn4"1" at pH 8 are on the order of 1.0 and 0.3 mole of Mn(II) sorbed per
mole of Mn02 and Fe(OH)3, respectively." Although this may explain the
removal of radium at these plants, further studies are required to confirm
this theory.
It was noted at several supplies that there was significant reduction in
radium-226 content after aeration and detention alone, before the water
was filtered. Further studies will be required to fully understand this
phenomenon.
Sodium Cation Exchange
Water softening by the sodium cation exchange (zeolite) process depends
upon the ability of certain substances to exchange cations with other cations
dissolved in water. When hard water is passed through a sodium cation ex-
changer, the calcium and magnesium in the hard water replaces the sodium
on the exchange medium. Because the reaction is reversible, after all of
the readily replaceable sodium has been exchanged, the cation exchange medium
can be regenerated with a solution of sodium chloride. In the regeneration
process, the calcium and magnesium on the exhausted cation exchanger are
replaced with a fresh supply of sodium from the regenerating brine solution.
Then, after washing to free it from the calcium and magnesium cations and
excess salt, the regenerated exchanger is ready to soften a new supply of
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TABLE 3
Ra-226 and Iron Removals at Water Treatment Plants Using Iron
and Manganese Removal Processes
Ra-226
City
Filter
Type
Sampling
Point
Iron and Manganese Removal Only
Adair
Stuart
Iron Exchange
Eldon
Estherville
Grinnell
Herscher
Holstein
Greensand
Anthrafilt
Pretreatment
Anthrafilt
Anthrafilt
None
Anthrafilt
Anthrafilt
Well
Filter Eff.
Well
Filter Eff.
Well
Filter Eff.
Well
Filter Eff.
Well
Detention Eff.
Well
Filter Eff.
Well
Filter Eff.
pCi/1
13
8
16
12
49
43
5.7
5.1
6.7
5.7
14.4
6.7
13
7.2
Percent
Removal
38
25
12
11
15
53
45
Iron
mg/1
1.1
0.02
0.94
0.03
2.0
0.3
2.0
0.67
0.71
0.41
0.1
0.0
1.8
0.05
Percent
Removal
98
97
85
66
42
97
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00
TABLE 4
Ra-226, Iron and Manganese Removals by Iron and Manganese Removal Processes
Ra-226 (pCl/1)
City
Adair
Eldon
Estherville
Grinnell
Herscher
Holstein
Stuart
Raw
6.9
pH 6.7-6.9
49
pH 7.8
5.7
pH 7.7
6.7
pH 7.6
14.9
14.5
14.9
14.3
14.0
13.9
13.9
14.1
14.3
pH 7.6-8.3
13
pH 7.4-7.6
16
pH 7.6-7.9
Treated
6.7
43
5.1
5.7
6.6
6.4
6.9
6.9
6.9
6.8
7.3
6.3
6.5
7
12
%Removal
3
12
11
15
56
56
54
52
51
51
47
55
55
46
25
Raw
0.5
2.0
2.0
0.7
0.2
0.4
0.1
0.1
0.1
0.1
0.2
0.1
0.1
1.8
0.94
Iron (mg/1)
Treated
0.01
0.3
0.67
0.41
0
0
0
0
0
0
0.1
0
0
0.09
0.03
%Removal
80
85
66
42
-
-
-
-
-
-
-
-
-
95
97
Manganese
Raw
0.01
0.01
0.24
0.01
0.47
0.41
0.48
0.39
0.45
0.63
0.44
0.53
0.50
0.15
0.01
Treated
0.01
0.01
0.27
0.01
0.02
0.01
0.01
0
0
0
0.13
0.02
0
0.01
0.01
(mg/D
%Removal
_
-
-
-
96
98
98
100
100
100
70
96
100
93
-
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hard water. The ion-exchange media studied included both naturally occur-
ring greensand and synthetic polystyrene resins (zeolite).
Ion exchange softening removes nearly 100% of the hardness from the treated
water. Consequently, unsoftened water is blended with the ion exchange
softener effluent to provide sufficient calcium carbonate for deposition
of a protective coating on the water mains and to reduce treatment costs.
Thus the water entering the distribution system usually has a greater radium
concentration than that leaving the softener. The radium concentration
in raw water could be the controlling factor in the amount of blending that
would be permitted in order to meet the radium limit in drinking water.
The results of the measurements at ion exchange process water treatment
plants are shown in Table 5.
The data shown from the plants in Illinois are the averages of nine separate
data points. Ranges in the percent reduction of radium-226 through softeners
at the three cities are:
Dwight 70.7 - 98.3
Herscher 68.4 - 93.9
Lynwood 94.7 - 98.2
It was determined that the removals vary somewhat over a softener cycle,
between regenerations. Radium-226 removal usually continues for a short
period after hardness breakthrough occurs. However, if the cycle continues
for a longer period after hardness breakthrough, radium-226 removal drops
rapidly.
Samples of softener brine and rinse effluent during regeneration were taken
at various times during the regeneration cycle. Regeneration normally re-
quires one to two hours. It was found that the major portion of the radium-
226 leaves the ion-exchange media over a rather short period - 10 to 30
minutes. Maximum radium-226 concentrations in the softener brine and rinse
effluents ranged from 320 to 3500 pCi/1.
Lime-Soda Ash Softening
This process of softening depends on the use of lime and soda ash to change
the soluble calcium and magnesium compounds into nearly insoluble compounds
which are flocculated, settled and filtered. Conditions for carrying out
the precipitation of calcium and magnesium vary because different pH levels
are needed for each, about pH 9.5 for maximum precipitation of calcium car-
bonate and pH 10.5 for maximum precipitation of magnesium hydroxide. Thus,
if the magnesium concentration is low, treatment to a pH of 9.5 will be
sufficient. If the magnesium concentration is high, excess lime, to produce
a pH of 10.5, can be used. A more economical treatment is to raise the
pH to 10.5 to precipitate the magnesium in a primary basin, then recarbonate
with carbon dioxide to pH 9.5 to precipitate excess calcium in a secondary
basin.
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TABLE 5
Ra-226 and Hardness Removals at Water Treatment Plants Using
Ion Exchange Processes
Softener
City Type
Dwight Correctional
Center Greensand
Eldon Zeolite
Estherville Zeolite
Grinnell Zeolite
Sampling
Point
Well
Softener Eff.
Distribution
System
Softener
Influent
Softener Eff.
Distribution
System
Softener
Influent
Softener Eff.
Distribution
System
Softener
Influent
Softener Eff.
Distribution
System
Ra-226
Percent
pCi/1 Removal
3.25
0.36 89
0.65
43
1.9 96
8.6
5.1
0.3 94
0.4
5.7
0.2 97
1.4
Hardness
mg/1
286
43
67
360
10
136
915
46
76
387
11
120
Percent
Removal
85
97
95
97
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TABLE 5 (cont.)
Ra-226 and Hardness Removals at Water Treatment Plants Using
Ion Exchange Processes
City
Herscher
Holstein
Lynwood
Softener Sampling
Type Point
Zeolite Softener
Influent
Softener Eff.
Distribution
System
Zeolite Softener
Influent
Softener Eff.
Distribution
System
Zeolite Well
Softener Eff.
Distribution
System
Ra-226
Percent
pCi/1 Removal
6.7
1.3 81
2.4
7.2
0.5 93
0.8
14.7
0.4 97
1.8
Hardness
mg/1
404
83
141
885
18
346
848
-
78
Percent
Removal
79
98
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Normally, soda ash is added as needed to precipitate non-carbonate hardness,
but due to a soda ash shortage, the West Des Moines plant was using only
a small quantity. The Webster City plant was using lime only during the
August, 1974 measurements, but was using soda ash during the February, 1975
restudy.
Results of measurements obtained at water treatment plants using lime-soda
ash softening are shown in Table 6. That the pH of the softening process
is a parameter that controls radium removal, at least for water containing
both calcium and magnesium, is demonstrated in Table 6 and in Figure 1.
The least squares fit for a straight line through the data points of Figure
1 indicates that the radium removal percentages increased as the pH of the
process increased.
The data shown from the plants in Illinois are the averages of three separate
data points, taken at approximate one-week intervals. Ranges in the percent
reduction of radium-226 at the two cities are:
Elgin 86.0 - 89.9
Peru 70.6 - 92.4
Samples of lime sludge and filter backwash water were also collected. The
results were:
Lime Sludge Filter Backwash
Ra-226 Ra-226
Elgin 6.1 pCi/g 18.3 pCi/1
Peru 9.0 pCi/g 36.9 pCi/1
Webster City 980 pCi/1 50 pCi/1
West Des Moines 2300 pCi/1 6.3 pCi/1
Pilot Plant (SO 75)*
The Environmental Protection Agency Municipal Environmental Research Labora-
tory, Cincinnati, Ohio, operates a conventional coagulation water treatment
pilot plant. The pilot plant, designed for flexibility in operation, is
capable of treating in parallel two 7.6 1/min. streams of water.
The two treatment systems each consist of two rapid mix tanks (in series),
flocculation basin, sedimentation basin, and one or more filters (in paral-
lel). The theoretical detention times for the mix tanks, and flocculation
and sedimentation basins are 1 minute, 60 minutes, and 6.5 hours respectively.
*We thank Mr. Thomas J. Sorg, Research Engineer, Municipal Environmental
Research Laboratory, U.S. Environmental Protection Agency, Cincinnati, Ohio,
for providing access to, and the operation of the pilot plant.
12
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TABLE 6
Ra-226 and Hardness Removals at Water Treatment Plants Using
Lime-Soda Ash Softening
Ra-226
City
Elgin
Peru
Webster City
(Aug. 1974)
Webster City
(Feb. 1975)
West Des Moines
Sampling
Point
Well
Filter Eff.
Well
Filter Eff.
Well
Clarifier #1 Eff.
Clarifier #2 Eff.
Filter Eff.
Well
Clarifier Eff.
Filter Eff.
Well
Contact Unit
Eff.
Filter Eff.
pCi/1
5.6
0.8
5.8
1.1
6.1
1.9
2.6
0.9
7.8
0.6
0.3
9.3
2.6
2.4
Percent
Removal
88
81
85
96
75
Hardness
mg/1
237
102
326
94
507
333
282
262
482
150
106
376
215
190
Percent
Removal
57
71
48
78
50
pH of
Process
10.0
10.1
9.3
11.0
9.9
10.1-10.4
9.4-9.5
-------
_ 100
o
>
o
E
o>
CC
I 8O
o
a:
0)
0.
60
10
Process pH
J
II
Figure I Radium Removal vs Softening pH
14
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The water to be treated is pumped to the first rapid mix tank. Normally,
the pH control chemical is added in the first mixing tank and coagulant in-
troduced in the second tank. From the mixing tanks, the water flows by gra-
vity through the flocculation and settling basins to the filters, which
consist of 10.8 cm diameter clear plastic cylinders providing 93 cm2 of
media surface area. A pump on the effluent side of each filter controls
the flow rate through the filter with the excess water wasted through an
overflow located several feet above the filter media. For the radium re-
moval studies, two parallel filters were used. One was a dual-media filter
containing 50.8 cm of No. 1-1/2 Anthrafilt over 30.5 cm of 0.4 mm effective
size Muscatine sand. The other filter consisted of 76.2 cm of granular
activated carbon, Filtersorb 200. The filtration rate was controlled at
163 1/min/m2.
The plant has instrumentation to record pH of the raw, flocculated, settled,
and filtered water; turbidity and temperature of the raw, settled, and fil-
tered water; head loss in the filters; and volumes of raw and filtered water
pumped.
Two test runs in August, 1975, were made to determine the removal of radium-
226 from Elgin, Illinois raw water by lime softening. The tests lasted
about 100 hours each and were run at pH 9.5 and 10.5. The raw water was
trucked from the Elgin Slade Avenue treatment plant to Cincinnati, Ohio.
For the first test run, lime, at 220 mg/1, was fed into the second rapid
mix tank to increase the pH to 9.5. Commercial grade lime was used and
fed as a 4 percent slurry. The water was then flocculated, settled and
filtered.
Duplicate one liter grab samples of the raw, settled and filtered water
were collected three times during the test period. The settled and filtered
samples were collected about 7 -hours after the raw sample, the approximate
time required for the water to flow through the flocculation and settling
basins. All samples were preserved with 1.5 ml of nitric acid.
The pilot plant was operated in a slightly different manner during the sec-
ond test run. For this test, 270 mg/1 of lime was added to increase the
pH to 10.5. After settling, the treated water was pumped through the other
treatment system where the water was recarbonated to lower the pH to 8.6,
settled for a second time, and then filtered. Grab samples were also col-
lected of the raw, settled, and filtered water. Water samples from the
first settling basin were collected about 7 hours after the raw sample.
Water samples from the second settling basin and filters were collected
about 14 hours after the raw sample.
Results of the two tests indicated that pH affects the removal of radium-
226 (Table 7). Lime softening at pH 9.5 resulted in removals of 79 percent
for settled water and 84 percent for filtered water. Excess lime softening
to a pH 10.5, achieved 92-93 percent removals in the settled water and 93-
95 percent in the filtered water. Little or no difference in removals were
noted between the two types of filters indicating that the carbon filter did
not achieve any additional removal by adsorption.
15
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TABLE 7
Ra-226 Removal in EPA Lime-Softening Pilot Plant
Using Elgin, Illinois Water
Raw
Settled
Dual-Media Filter
Activated Carbon Filter
Raw
First Settling Basin
Recarbonation Settling
Basin
Dual-Media Filter
Activated Carbon Filter
Softened to pH 9.4 - 9.5
August 6, 1975 August 7, 1975 August 8, 1975
Average
Cone.
pCi/1
4.19
1.03
0.79
0.75
Softened
D.F
75.
81.
82.
to
August 20,
Cone.
pCi/1
4.78
0.37
0.33
0.30
0.18
D.F
92.
93.
93.
96.
. ,%*
4
1
1
pH
1975
7
. , /o
4
1
7
2
Cone.
pCi/1
3.95
0.94
0.65
0.62
Cone.
D.
76
83
84
F.,%
.1
.6
.4
P
4
0
0
0
10.6, Recarbonation
August
Cone.
pCi/1
4.86
0.39
0.36
0.30
0.28
21,
1975
Ci/1
.87
.69
.61
.65
to pH
D.F.
85.9
87.4
86.6
8.7
Cone.
,% p
4
0
0
0
Ci/1
.34+. 48
.89+. 18
.68+. 09
.67+. 07
D.F.,%
79.1+5.9
84.0+3.2
84.3+2.3
Average
Cone.
D.
92
92
93
94
F.,%
_
.0
.5
.8
.3
P
4
0
0
0
0
Ci/1
.82+.
.38+.
.35+.
.30+.
.23+.
19
02
02
00
07
D.F
_
92.
92.
93.
95.
. ,%
2+0.3
8+0.4
8+0.1
2+1.3
*D.F. - Decontamination Factor (The Removal Efficiency)
-------
SUMMARY OF RESULTS
The radium removal efficiencies of four water treatment processes are shown
in Table 8.
TABLE 8
Ra-226 Removal Efficiencies in Water Treatment Processes
Process
City
Percent Removal
Reverse Osmosis
Iron Removal
Ion Exchange
Lime-Soda Ash
Softening
Greenfield, Iowa
Adair, Iowa
Eldon, Iowa
Estherville, Iowa
Grinnell, Iowa
Herscher, Illinois
Holstein, Iowa
Stuart, Iowa
Dwight Correctional
Center, Illinois
Eldon, Iowa
Estherville, Iowa
Grinnell, Iowa
Herscher, Illinois
Holstein, Iowa
Lynwood, Illinois
Elgin, Illinois
Peru, Illinois
Webster City, Iowa, pH 11.0
West Des Moines, Iowa, pH 10.1
Cincinnati Pilot
Plant, pH 9.5
Cincinnati Pilot
Plant, pH 10.6
96
38
12
11
15
53
45
25
89
96
94
97
81
93
97
88
81
96
75
84
95
17
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REFERENCES
EN 76 Environmental Protection Agency, 1976, "40 CFR 141 Interim Primary
Drinking Water Regulations, Radionuclides," Federal Register 41, 28402.
BE 76 Bennett, D.L., Bell, C.R. and Markwood, I.M. , 1976, USEPA Rept. ORP/
TAD-76-2, "Determination of Radium Removal Efficiencies in Illinois Water
Supply Treatment Processes."
FA 68 Fair, G.M., Geyer, J.C., Okun, D.A., 1968, Water and Wastewater
Engineering, Vol. 2.
MO 72 Moore, D.H., 1972, "Greenfield, Iowa, Reverse Osmosis Desalting Plant,
"Journal American Water Works Association, 64, 781.
MO 75 Moore, W.S., Cook, L.M., 1975 "Radium Removal from Drinking Water,"
Nature, 235.
SC 76 Schliekelman, R. J., 1976, USEPA Rept. ORP/TAD-76-1, "Determination
of Radium Removal Efficiencies in Iowa Water Supply Treatment Processes."
SO 75 Sorg, T. J., 1975, Personal Communication, USEPA, Municipal
Environmental Research Laboratory, Cincinnati, Ohio.
18
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
ORP/TAD-76-5
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND~SUBTITLE
Determination of Radium Removal Efficiencies in Water
Treatment Processes
5. REPORT DATE
1976
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
W.L. Brinck, R.J. Schliekelman, D.L. Bennett,
C.R. Bell, I.M. Markwood
8. PERFORMING ORGANIZATION REPORT NO.
ORP/TAD-76-5
9. PERFORMING ORG "XNIZATION NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Radiation Programs
Washington, D.C. 20460
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Same as 9
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
EPA-ORP
15. SUPPLEMENTARY NOTES
16. ABSTRACT
Numerous well-water supplies for public water systems contain naturally occuring
radium-226. Methods for removing radium from drinking water are needed so that
drinking water treatment plants may meet the limit set in the EPA drinking water
regulations for radium in drinking water.
Studies were performed by State agencies at 14 cities in Iowa and Illinois to
determine the radium removal efficiency of four water treatment processes. Popu-
lations served by the water treatment plants ranged from 235 to 25,000. The
radium-226 concentration in the raw water was greater than 5 pCi/liter at 13 of the
supplies and ranged from 3 to 49 pCi/liter.
Radium removal efficiencies at plants utilizing reverse osmosis and sodium ion-ex-
change processes were generally about 92%. A much wider range of removal
efficiencies, 75% to 95%, was found at plants utilizing the lime-soda ash softening
process with the removal varying with process pH. Plants utilizing iron removal
processes only were found to have radium removals ranging from 11% to 53%.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
cos AT I Field/Group
Water, Treatment, Removal
Radioactivity, Radium
Potable Water
Natural Radioactivity
Water Treatment
Chemical Removal
13. DISTRIBUTION STATEMENT
19. SECURITY CLASS (ThisReport)
21. NO. OF PAGES
Unclassified
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
-.VU.S. GOVERNMENT PRINTING OFFICE: 1977-757-056/5640 Real on No. 5-||
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