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NOTICE
This report has been reviewed by the Office of Toxic Substances,
Environmental Protection Agency, and approved for publication. Approval
does not signify that the contents necessarily reflect the views and
policies of the Environmental Protection Agency. Mention of tradenames
or commercial products is for purposes of clarity only and does not con-
stitute endorsement or recommendation for use.
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PREFACE
This report presents the results of Task II of a project entitled
"Chemical Technology and Economics in Environmental Perspectives," per-
formed by Midwest Research Institute (MRl) under Contract No. 68-01-3201
for the Office of Toxic Substances of the U«S» Environmental Protection
Agency. Dr. Irving Gruntfest was project officer for EPA.
Task II "Removal of Boron from Wastewater," was conducted by
Dr. Thomas ¥• Lapp, Associate Chemist, who served as project leader, and
Mr. Gary R. Cooper. This report was prepared under the supervision of
Dr. E. W. Lawless, Head, Technology Assessment Section. Dr. I. C. Smith,
Senior Advisor for Environmental Science, provided technical consultation.
This program had MRI Project No. 4101-C.
MRI would like to express its sincere appreciation to the several
companies who provided technical information for this report.
Approved for:
MIDWEST RESEARCH INSTITUTE
. \- ,^/J\*-A~xvw*^rv\.
L. J/ Shannon, Assistant Director
Physical Sciences Division
June 28, 1976
ii
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CONTENTS
Page
List of Tables iv
Sections
I Introduction ..................... 1
Objectives of this Program ............. 2
References for Section I... ........... 3
II Summary and Conclusions. ............... 4
III Background ...................... 6
Occurrence ..................... 6
Production ..................... 6
Consumption of Boron and Compounds ......... 7
Boron Loss to the Environment. ........... 8
References to Section III. ............. 10
IV Methods of Removal of Boron. ............. 11
Current Practices. ................. 11
Current and Past Methods of Removal. ........ 14
Possible Methods of Removal. ............ 19
References for Section IV. ............. 24
•iii
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TABLES
Table Title Page
Current Borax Producers, Locations and Capacities • • • 7
Consumption of Boron Compounds in 1973* •••••••• 8
Estimated Tons of Boron Entering the Environment
in 1972 9
4 Boron Adsorption with Amberlite® XE-243 •• 14
5 Cost Estimates for Deboronation Plants Using Amberlite®
XE-243 Ion-Exchange Resin 15
6 Liquid-Liquid Extraction Reagents ••••••••••• 17
7 Boron Extraction Compounds and Solvent Carriers .... 18
iv
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SECTION I
INTRODUCTION
Boron is an ubiquitous element in the natural environment. It occurs
as the oxygenated forms of borate salts or boric acid and these substances
are widely used for the industrial and domestic purposes. The concern for
the influence of boron on life forms can be focused on three areas: (a)
man; (b) plant life, both terrestrial and aquatic; and (c) lower forms of
animal life, including microorganisms.
Boron has not been shown to be an essential element to man, and,
while toxicity values are quoted,il=/ some questions remain regarding its
effect on man. It is essential to proper growth of plants but, at the
same time, higher concentrations of boron are extremely toxic to many
plant species; the differences between concentrations that are best for
plant growth and toxic concentrations are often very small. For example,
some citrus species require trace boron soil concentrations to produce
optimum growth, yet exhibit toxic effects at the 1 ppm level in the soil.
Therefore, water intended for irrigation is often classified as to its
applicability to crops sensitive to boron. Most problems of toxicity to
agricultural crops are confined to areas of Southwestern United States
where the natural boron content of soils is appreciably higher than in
other regions. In other areas where the background level is low, quanti-
ties may be added to fertilizers for positive effects on crop growth and
production*-!/
Aquatic plants are also susceptible to boron toxicity. The natural
boron content of surface waters averages 0.1 ppm in the United States;
whereas seawater averages 4.6 ppm.V Boron concentrations of greater than
0.1 ppm would likely occur in discharges of industrial or domestic wastes.
In the event that consumption of boron compounds in detergent formulations
increases, aquatic plant life may be subjected to toxic effects from in-
crrnsod conccntm Lions In the surface waters.
Another'area of concern is the^toxic effect of boron on microorgan-
isms, especially those associated with sewage treatment. In trace quanti-
ties, it has been shown to be an essential element for some microorganisms.
I
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The published literature on the effects of boron on the various sewage
treatment processes is not extensive, but studies have shown that for
concentrations above 10 ppm, toxic effects occur in concentrated syn-
thetic substrate solutions.
OBJECTIVES OF THIS PROGRAM
The objectives of this program were to: (a) ascertain the degree
of concern over boron in industrial waste streams and municipal sewage
streams; (b) determine what industries are currently engaged in the re-
moval of boron from their waste streams; (c) determine current methods,
if any, and their effectiveness for the removal of boron as boric acid
and borates from industrial waste streams and municipal waste treatment
systems; (d) survey the published literature for methods of boron re-
moval that may have merit for future application to industrial waste
streams and their effectiveness; and (e) determine the effect that boron
may have on the microorganisms present in the active sludge of sewage
treatment processes. Wherever possible, published or estimated cost anal-
yses for the removal of boron are to be stated for the methods found in
objectives (c) and (d).
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REFERENCES FOR SECTION I
1. Versar, Inc., Preliminary Investigation of Effects on the Environment
of Boron, Indium, Nickel, Selenium, Tin, Vanadium, and Their Com-
pounds, Vol. I, Boron, EPA 56/2-75-005A, U.S. Environmental Pro-
tection Agency, Washington, D.C. (1975), NTIS No. PB 245984/AS.
2. Registry of Toxic Effects of Chemical Substances, 1975 Edition, U.S.
Department of Health, Education and Welfare, Public Health Service,
Center for Disease Control, National Institute of Occupational Safety
and Health, Rockville, Maryland, p. 231.
3. Christensen, H. E., T. T. Luginbyhl, Eds., Suspected Carcinogens,
U.S. Department of Health, Education, and Welfare, U.S. Government
Printing Office, Washington, D.C. (1975).
4. Sprague, R. W., The Ecological Significance of Boron, The Ward Ritchie
Press, Los Angeles, California (1972).
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SECTION II
SUMMARY AND CONCLUSIONS
Boron is a very common element in nature, occurring as the borate
or as boric acid. While the toxicity of borate and boric acid has not
been clearly established for man, it can be toxic to plants and micro-
organisms. The toxicity to plants requires further comment: boron is
also an essential element to plant growth and the range between its
beneficial and toxic concentrations can be very small. Because of in-
creasing consumption of soaps and cleaners, the primary commercial
source of boron entering the environment, an increase in the boron con-
tent of many wastewaters, and therefore many surface waters, could occur.
The purpose of this brief study was to determine the degree of gen-
eral concern regarding the presence of boron in industrial waste streams
and municipal sewage systems and to ascertain if any industries or cities
are currently engaged in the removal of boron from their waste streams.
If removal is currently practiced, the methods of removal, their effec-
tiveness, and cost analysis were to be determined. Methods of boron re-
moval that may have merit for future applications were also to be studied.
An attempt was also made to determine the effect of boron on microorganisms
present in municipal waste treatment systems•
The results of this study have shown that basically no industries or
municipal sewage treatment facilities are currently removing boron from
waste streams and that no real concern is presently being expressed re-
garding the presence of boron in either industrial waste streams or mu-
nicipal sewage systems. In certain industries,. boron is removed but not
because of concern for the environment. California has imposed an effluent
standard of 0.5 ppm for boron.
The toxic effects of boron on microorganisms found in waste streams
and municipal sewage treatment facilities can vary depending on condi-
tions. A significant reduction in microorganism activity occurred in con-
centrated substrate solutions at boron concentration levels greater than
10 ppm. The concentrated substrate solutions would be representative of
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those present in municipal waste treatment systems. In contrast, in di-
lute substrate solutions approximating a waste stream, boron concentra-
tions as high as 100 ppm showed little effect on microorganism activity.
Three methods for the removal of boron from water have been or are
currently being used by industry. These methods are: (a) ion-exchange
resins (Amberlite® XE-243), lime precipitation, and liquid-liquid extrac-
tion. Eight additional methods have been identified that may have varying
degrees of merit for future applications in the removal of boron from
waste streams.
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SECTION III
BACKGROUND
This section will present a brief review of boron with respect to
natural occurrence, major producers and their processes, consumption in
various use areas, and losses to the environment.
OCCURRENCE^/
Boron is a widely occurring element comprising about 0.0003% of the
earth's crust, including fresh water and seawater. This compares to the
most abundant metal, aluminum, which comprises 8.13%. The boron content
of soils is quite variable and highly dependent upon soil porosity,
amount of rainfall, specific type of soil and the quantity of soil or-
ganic matter. Igneous rocks contain the least amount of boron, averaging
about 10 ppm. Sedimentary rocks contain the highest quantity, depending
upon their origin, and average about 30 ppm with the highest concentra-
tion occurring in marine shales (up to 300 ppm).
A large percentage of the earth's boron is contained in the ocean,
where the average concentration is about 4.6 ppm. The boron content of
surface waters is generally low, e.g., 0.1 ppm average in the U«S«, with
a range of 0.02 ppm for the Western Great Lakes Basin to 0.3 ppm for the
Western Gulf Basin.
Based on 1967 worldwide production values, coal contains an average
of 75 ppm boron and the combustion of coal was estimated to contribute
approximately 11,600 tons of boron, in the form of fly ash, to the world's
atmosphere*2/ Data presented in another report give two values for the
quantity of boron emitted to the atmosphere from coal combustion in the
U«S« For 1972, values of 4,400 and 4,675 tons were given; no reasons were
provided for the discrepancy in the two figures•£/
PRODUCTION
The United States is the world's major source of boron compounds,
contributing about 70% of the world production. U»S« Borax and Chemical
Corporation is the leader in world production of borax and other borate
chemicals.
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Table 1 lists current domestic producers, locations and annual ca-
pacities.
Table 1. CURRENT BORAX PRODUCERS, LOCATIONS AND CAPACITIES3-^/
Annual capacity
Company Location (thousands of tons)
Kerr-McGee Corporation
Kerr-McGee Chemical
Corporation subsidiary Trona, California 100
West End, California 26
U«S« Borax and Chemical
Corporation Boron, California 500
Stauffer Chemical
Corporation Trona, California 28-33
In addition to the producers of borax and refined borates listed
above, Tenneco Oil Company (a division of Tenneco, Inc.) produces cal-
cined colemanite (Ca^B^On) at Furnace Creek, California. The design
capacity is approximately 77,000 tons annually.^/
A plant for borax production, with a design capacity of 27,000 tons,
has been planned by Searles Lake Chemical Company, a subsidiary of Oc-
cidental Petroleum Corporation. The plant was scheduled for completion
in 1974; however, it may have been postponed indefinitely*?.'
CONSUMPTION OF BORON AND COMPOUNDS
A1 :
Listed in Table 2 are estimated amounts and percentages of boron
compounds consumed in 1973.
Miscellaneous uses included: fluxing materials, nonferrous deoxi-
dizer, grain refiner in aluminum, thermal neutron absorbers, delayed ac-
tion fuses, ignitor in radio tubes, coating material for solar batteries,
abrasives, catalyst chemicals, conditioning agents for chemicals, precursor
to chemicals, plasticizers, adhesive additives, fire retardants, antifreeze,
textile and paper additives, biocides, photographic chemicals and as com-
posite materials—'
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Table 2. CONSUMPTION OF BORON COMPOUNDS IN 1973
Estimated amount
Industry % (as Boron)j/ (tons as boron)
Glass manufacture 40-45 41,000-46,000
Soaps, cleaners 15 15,000
Enamels, frits, glazes 10 10,000
Fertilizer 5 5,000
Herbicides 2-3 2,000-3,000
Miscellaneous 25 26,000
Total 99,000-105,000
In addition, more than half of the domestic production is exported,
largely as crude borates«2/ Much of this exportation goes to Europe where
sodium perborate is used in detergent formulations as a bleaching agent.
This contrasts with U»S» practices of using chlorine compounds in deter-
gent formulations for their bleaching properties.
BORON LOSS TO THE ENVIRONMENT
Boron may be lost to the environment at several points during the
mining and processing of the ore and during consumption of the various
boron compounds by industrial and domestic users. Combustion of coal and
sewage sludges are sources of loss to the environment and contribute a
major portion of the boron air emissions.
Table 3 shows the estimated amounts lost to the environment in 1972;
estimated losses are given for air emissions, water and solid waste dis-
charges, and total estimated losses. The values for water and solid waste
discharges were obtained by the difference between the total losses and
losses through air emissions.
The major source of boron loss to water is from soaps and cleaners.
Nearly all of the boron, as borax, compounded into soap, detergent and
cleaner formulations is for the consumer market and does not often appear
in industrial waste effluent streams. Agricultural sources of boron in
water result from the use of its compounds as herbicides and also as a
trace element addition to fertilizers. Railroads use large amounts of
chlorate herbicides that contain a high percentage of borate as a fire
retardant. Boron in industrial waste streams would arise during the
processing of borax and other compounds and in the miscellaneous use cat-
egories. Some boron should also appear in water effluents from glass
and ceramic manufacture.
8
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Table 3. ESTIMATED TONS OF BORON ENTERING THE ENVIRONMENT IN 19721/
Category
Mining and
processing
Glass and
ceramics
Agricultural
Soaps, cleaners
Miscellaneous
Coal combustion
TOTAL
Total amounts
(air, water, solid waste)
3,300
1,650
7,700
15,400
2,750
4, 675^
35,475
Air emissions
2,740
1,619
1,980
34
550
4,675
11,598
Estimated water and
solid waste discharges
560
31
5,720
15,366
2,200
0
23,877
a_/ Two values (4,400 and 4,675 tons) for coal combustion were given in Reference 3. The
air emissions value was chosen to maintain continuity within the table.
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REFERENCES TO SECTION III
1. Sprague, R. W., The Ecological Significance of Boron, The Ward Ritchie
Press, Los Angeles, California (1972).
2. Bertine, K. K., and E. D. Goldberg, Science, r7.3:233 (1971).
3. Versar, Inc., Preliminary Investigation of Effects on the Environment
of Boron, Indium, Nickel, Selenium, Tin, Vanadium, and Their Com-
pounds, Vol. I, Boron, EPA-56/2-75-005A, U.S. Environmental Pro-
tection Agency, Washington, D.C. (1975), NTIS No. PB 245984/AS.
4. Chemical Information Services, 1975 Directory of Chemical Producers,
United States of America, Stanford Research Institute, Menlo Park,
California (1975).
5. Wang, K. P., "Boron" in: Minerals Yearbook, 1973. Vol. I. Metals,
Minerals and Fuels, Bureau of Mines, U.S. Department of the Inter-
ior, U.S. Government Printing Office, Washington, D.C. (1975).
10
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SECTION IV
METHODS OF REMOVAL OF BORON
This section describes the current industrial and sewage treatment
practices for removal of boron from waste streams, the effect of boron
on municipal waste treatment systems, current and past methods of re-
moval and potential methods for removal from waste streams.
CURRENT PRACTICES
Industrial
The practice of boron removal from waste streams occurs primarily
only during the mining and primary recovery of boron from ores and brines.
At no other stage in the processing were data found indicating that it
is removed from waste streams.
As indicated previously, about 70% of the world production of boron
originates in the U«S« and this domestic production is all located in
the southeastern part of California.
United States Borax and Chemical Corporation treats wastewater ef-
fluents from its mining and primary recovery operations by evaporation
of the excess water on impervious evaporation pads. In this process, ore
is extracted with hot water, the liquor purified by cooling, precipita-
tion and redissolving with hot water. The final products are sodium tetra-
borate, borax (decahydrate), the pentahydrate, and anhydrous sodium
tetraborate*i/ Excess process water is sent to the evaporation pads which
produce no effluent. Water is recycled in the process as applicable.
The Kerr-McGee Chemical Corporation recovers borax and boric acid
from the brines of the Searles Lake. Searles Lake is a dry lake and all
excess process water is returned to the lake. Kerr-McGee has no true ef-
fluent water. The Kerr-McGee process entails both evaporative crystal-
lization and solvent extraction for recovery of various salts, including
11
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2/
borax and boric acid*-' Stauffer Chemical Company, also at the Searles
Lake location, presumably treats its aqueous effluent by returning it to
the lake*
During the secondary processing of borax and the other tetraborates
to produce boric acid and other compounds, no evidence was found that in-
dustry attempts to remove boron from wastewaters. It has been reported
that U.S. Borax discharges wastewater from the Wilmington, California,
plant directly into the ocean«2/ This plant produces boric acid and other
boron compounds using the tetraborates from their mining production.
Another secondary processor, Eagle-Picher Industries at Miami,
Oklahoma, does not attempt to remove boron from the waste stream from the
the manufacture of boron tribromide, boron trifluoride, and other boron
compounds* The waste effluent is discharged into a sanitary sewer and has
a typical analysis of < 10 ppm boronJt/
Among the boron-consuming industries, only one reference^/ was found
indicating that boron was removed from wastewater* The waste stream was
from painting, cleaning, and electroplating processes. The waste treat-
ment system was primarily for the removal of cyanide ion and chromium. Ef-
fluents from the treatment system contained 0.04 ppm boron but no initial
boron concentration was stated in the article. Considering the sources of
the waste stream, it is likely that the boron was initially present as the
borate ion and possibly the fluoborate ion. If the fluoborate ion was ini-
tially present, the alkaline treatment conditions for the cyanide ion would
have readily hydrolyzed the fluoborate ion to borate and fluoride ions by
the sequential loss of fluorine.
No other instances were discovered where boron is removed from indus-
trial wastewater streams. Inquiries to U.S. Borax— and Kerr-McGee£/ were
made, but neither had any knowledge of industries removing boron from
waste streams. Rohm and Haas Company.!/ had no knowledge of any industry
using their Amberlite© XE-243 ion-exchange resin to remove boron from
waste streams.
Boron is considered a contaminant only in industries related to very
special applications.— Due to its extremely high thermal neutron cross-
section industries directly concerned with the production of materials
and chemicals for nuclear reactors must be especially cognizant of the
boron content of the water supply. The boron content in materials used
in the construction and chemicals used in nuclear reactors must be very
low. Seawater being used for the production of magnesium oxide and mag-
nesium chloride brines processed for magnesium metal must maintain a low
boron content if the end products are intended for use in nuclear reactors.
For irrigation water, a standard of 1 ppm boron has been established but
this limit is normally attained through dilution with low boron content
water.
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Sewage Treatment
No indication was found that any sewage treatment plants attempt to
specifically remove boron from sewage wastes, either municipal or indus-
trial. California has adopted a standard of 0.5 ppm of boron for effluent
discharges from industry and municipalities. This standard was adopted
primarily for the benefit of irrigation water. No attempts are being made
in the waste treatment plants to specifically remove boron since the con-
tent of the incoming sewage is generally at or below the effluent discharge
standard. Some violations occurred but only in the 0.7 to 0.8 ppm range
and these were associated with the borax producers. At the present time,
the State of California does not have any concern over the boron levels
in sewage.8"10/
Boron may be inadvertantly removed in sewage treatment through ad-
sorption on organic matter or by absorption by microorganisms. It is an
essential trace element for the growth of some microorganisms«JLi/ Digested
sewage sludge collected from several municipal sewage treatment plants in
Connecticut indicated an average boron content of 211 ppm, ranging from
160 to 360 ppm*i£' However, another widely quoted source indicates that
boron is not removed by conventional sewage treatment as applied in Great
Britain.-^
Tests on the effects of boron (as boric acid and sodium borate) on a
synthetic substrate have shown that boron, in slug doses, lowers the rates
of biological processes. This study employed concentrated substrate solu-
tions, approximating the conditions found in waste treatment plants. At
levels greater than 10 mg/liter in an aerobic biological waste treatment
plant, boron was found to appreciably lower the COD removal rate.~ The
authors did not report either the corresponding BOD removal rate or the
relationship between BOD and COD for the synthetic waste under investiga-
tion. It is reasonable to assume, however, the BOD removal rate would be
lower than the corresponding COD removal rate by a factor of 2 or 3. The
authors concluded, however, that present levels in wastewater (•** 0.5 ppm)
should pose no problems unless boron is adsorbed or concentrated on the
sludge.
Another study was conducted to determine the effect of boric acid on
BOD removal.—' The study involved finding the concentration of boric acid
which would produce a 50% inhibition of oxygen utilization, TC5Q» The re-
sults for boric acid were found to be > 1,000 mg/liter, indicating that
boric acid has negligible effect on the BOD test over a wide range of con-
centrations.
The studies described above all involved slug dosing of the synthetic
*
sewage systems with boron compounds. In a municipal sewage system, the
boron will normally be present at concentrations of about 0.5 to 1.0 ppm.
In this case, the microorganisms could become acclimated to the boron and
less sensitive to its toxic properties.
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CURRENT AND PAST METHODS OF REMOVAL
This subsection will discuss past and present methods for the removal
of boron, as boric acid and borates, from wastewater streams. Again, no
evidence was found indicating that boron is currently being removed from
waste streams except during mining and initial recovery of natural boron.
Only two applications were found where boron is removed from process
streams, aside from primary recovery of boron from ore or brines. These
two applications are in the recovery of magnesium from seawater and re-
moval of boron from water used in nuclear reactors.
The three methods which have been or are currently being used on an
industrial scale for the removal of boron from water are: (a) ion-exchange
resins; (b) lime precipitation; and (c) liquid-liquid extraction.
Ion-Exchange Resins (Aroberlite® XE-243)
Rohm and Haas Company currently produces a boron specific ion-exchange
resin, Amberlite® XE-243 (Amberlite IRA-943, the commercial designation).i£
This material is a macroreticular resin based on the amination of chloro-
methylated styrene-divinylbenzene with N-methylglucamine. At the present
time, the primary application of this resin is in the removal of boron from
seawater brines during the recovery of magnesium.-!' Extensive testing was
conducted on simulated irrigation-return water by Aerojet-General Corpora-
tion, and Amberlite® XE-243 was found to be the only method available to
effectively remove boron to the < 1 ppm level.-^
Listed in Table 4 are some factors relating to boron adsorption with
Amberlite® XE-243.
Table 4. BORON ADSORPTION WITH AMBERLITE® XE-243
Characteri st ic Reference
1. Works best on dilute solutions 19
2. Other salts do not interfere 21
3. May be subject to chemical and/or biological
degradation 17
4. Low capacity, i.e., 0.36 Ib B/ft3 20
5. High operating costs 19
6. High initial cost, i.e., $170/ft3 7
7. May be fouled by solids 13
14
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Following, in Table 5, is a summary of cost estimates for a one MGD
plant using Amberlite® XE-243 ion-exchange resin. These estimates are from
two studies: one completed by Aero-Jet General Corporation!!' and the
other by Dow Chemical Company*!^' The treated water cost does not include
costs for ultimate disposal of the concentrated boron wastes generated
during operation.
Table 5. COST ESTIMATES FOR DEBORONATION PLANTS USING
AMBERLITE® XE-243 ION-EXCHANGE RESIN
Aero-Jet Dow Dow
Capacity (MGD)
Resin size (mesh)
Flow rate (gpm/ft2)
Resin volume (ft3)
Installed capital cost ($)
Assumed labor cost ($/hr)
Assumed power cost (0/kwh)
Initial boron concentration (ppm)
Final boron concentration (ppm)
Assumed resin cost ($/ft3)
Treated water cost (#/l,000 gal)
1
-16 + 50
12
310
83,000
2.50
0.7
10
< 1
105
12
1
-16 + 50
10
320
200,000
4.50
0.7
10
< 1
105
23
1
-40 + 50
10
320
200,000
4.50
0.7
10
< 1
105
21
In the study by Dow, estimates were also made for a 10 MGD plant.
The most favorable cost per 1,000 gallons of water was about 12£ for a
plant using -40 + 50 mesh resin at a bed flow rate of 20 gpm/ft2-
The current cost for Amberlite® XE-243 resin is as follows:
Quantity (ft3) Cost ($/ft3)
40-199 171.90
200-399 170.70
At a present resin cost of $170/ft3 3 instead of the $105 assumed in Table 5,
an additional expense of approximately 70/1,000 gal of water should be
added to the cost figures assuming a resin life of 1 year. No inquiry was
made as to the availability of a resin size -40 + 50 mesh. That specifica-
tion may also add to the cost of the installed resin.
It has been stated that Amberlite® XE-2'43 is the only currently
feasible method for the effective removal of boron from dilute industrial
waste streams £'
15
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Lime Precipitation and Filtration
It has been reported that lime precipitation and subsequent filtra-
tion is effective to a degree in the removal of boron. Boron, in the form
of boric acid or borates, is coprecipitated with other calcium salts.
(Calcium borate has a solubility in water equivalent to about 620 ppm of
boron.)i2/ In laboratory experiments on water containing 10 ppm boron,
lime precipitation was found to be less than 25% effective»LU No cost es-
timates were found in the literature.
Lime precipitation also is not specific to boron, produces a sludge
posing further disposal problems, and the effluent water is highly alka-
line. Waggot reported about 15% boron removal from a sewage treatment
effluent containing < 2 ppm boron JLi'
Because of the ineffectiveness of this process as a primary method
for the removal of boron from wastewater, no cost estimates have been
made for this method.
The Dow Chemical Company has used excess lime to precipitate magne-
sium from seawater and to prevent the coprecipitation of boron. During
the precipitation process, the small quantities of boron present in the
wastewater (6 to 12 ppm) remained in solution22J This system has been
phased out in favor of an ion-exchange process.based on the Rohm and Haas
resin discussed in the preceeding subsection——'
Liquid-Liquid Extraction
A likely candidate for the removal of boron from industrial waste
streams is liquid-liquid extraction. For this extraction process, a water
insoluble polyhydroxy compound is dissolved in a suitable solvent which
is immiscible with water and of different specific gravity. Boron is ex-
tracted from the aqueous phase into the solvent phase by complexation.
Boron, as borax, is presently extracted from weak brines by Kerr-
McGee Corporation in this manner. This system was developed specifically
for weak brines and plant end liquors having boron concentrations of the
order of 1.7%J£/ No data were presented for the low concentrations
(10 ppm) anticipated in wastewater so the potential applicability of the
system to waste streams is unknown. No cost data relative to the weak
brines were presented in any of the publications.
Table 6 lists several patented chemical compounds reportedly usable
for liquid-liquid extraction of boron.
An article reviewing the patent U.S. 3,111,383 assigned to American
Potash and Chemical Corporation indicated that more than 25 compounds
were cited in the patent Ji5-/ Table 7 lists some of the compounds and car-
rier agents.
16
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Table 6. LIQUID-LIQUID EXTRACTION REAGENTS
Chemical name
Patent No.
Patent holder
1,8-Naphthalenediol
5-(l,l,3,3-tetramethylbutyl)
salicylic acid
Polyol27,b/
4-t-Bu ty 1 -cat echo \£]
6 to 16 Carbon aliphatic
diol or triol
15 Annular carbon homocyclic
aromatic polyol
Substituted cat echo Is0-'
7 to 20 Carbon substituted
hydroxy benzyl alcohols
8 to 20 Carbon aliphatic
vicinal diol
3 to 12 Carbon alkyl or
alkoxy substituted 4-
catechol
Halogen substituted 4-
catechol
Brit. 910,541
U.S. 3,839,222
U.S. 2,969,275
U.S. 3,111,383
U.S. 3,424,563
U.S. 3,424,563
U.S. 3,433,604
U.S. 3,433,604
U.S. 3,433,604
American Potash and
Chemical Corporation^'
E. A. Grannen
Dow Chemical Company
Dow Chemical Company
American Potash and
Chemical Corporation
American Potash and
Chemical Corporation
Dow Chemical Company
Dow Chemical Company
Dow Chemical Company
Dow Chemical Company
Dow Chemical Company
_a/ Now subsidiary of Kerr-McGee Corporation
b/ OH
X Jl ,CH2OH
28/
_c/ Used in conjunction with 12 to 30 carbon water immiscible alkyl am-
monium salts.
17
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25/
Table 7. BORON EXTRACTION COMPOUNDS AND SOLVENT CARRIERS^
Extraction compound Solvent carrier
2-Chloro-4-(l,l,3,3-tetramethylbutyl)- Kerosene
6-methylolphenol£'
1-2-Diphenylglycol Methyl isobutyl ketone and
tributylphosphate
2,6-Dimethylol-4-octylphenol Kerosene and decanol (1:1)
2,6-Dimethylol-4-nonylphenol Kerosene and decanol (1:1)
4,6-Dichlorosaligenin Benzene and decanol
4-£-Butyl-6-chlorosaligenin (90%) Benzene
4-£-Butyl-6-raethylsaligenin (90%) Kerosene
4-Chloro-6-cyclohexylsaligenin (90%) Octanol
a/ Iflhile this compound was listed as the preferred compound in the
patent, all of the other compounds had a relative extraction
coefficient at least as high or higher than the preferred com-
pound* The principal problems associated with the other com-
pounds relate to extractant stability and solubility in water.
The preferred compound has a distribution coefficient of 80
(ratio of percent boron in organic phase to aqueous phase)*
18
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Solvent extraction studies in 36% magnesium chloride brine solutions,
at initial boron concentrations of 0,21 to 0,85 g/liter, confirmed the
affinity of 4-1:- butyl-cat echo 1 for boron in the form of boric acid,££/
However, one test showed poor extraction results at low (12 ppm) boron
concentration: 10 ppm boron remained in the aqueous phase. For aqueous
systems, of the type encountered in most waste streams, the solubility of
^-butyl catechol in water would probably prevent this system from being
highly efficient. The substitution of larger alkyl groups for the _t-butyl
group may decrease the water solubility and improve the efficiency. How-
ever, no studies have been conducted on the effect of different alkyl
groups in the solubility. Using _t-butyl catechol, it has been estimated
that the cost of this system would be approximately $0.50 to 0.75/1,000
gal.—
POSSIBLE METHODS OF REMOVAL
In this subsection, methods having potential for the removal of boron,
as boric acid and borates, from industrial waste streams will be discussed.
Strong Basic Anion-Exchange Resins
Ion-exchange resins of the strongly basic type could be used to remove
boron from industrial waste streams,— Two major drawbacks would occur
with the use of these resins: (a) strong basic ion-exchange resins are
highly pH dependent, i.e., maximum absorption is at pH 7.5 to 9,0 with
almost no absorption at pH 5;—' and (b) strong basic ion-exchange resins
are not specific to boronJi'
A patent, U.S. Patent 3,856,670, was issued to Occidental Petroleum
Corporation for an anionic ion-exchange resin, which reportedly will se-
lectively remove borates from water«2jV The resin was produced by the co-
condensation reaction of an aromatic orthohydroxy acid, a phenolic com-
pound and an aldehyde. The patent claimed that borate is removed in the
presence of alkali, alkaline earth, nitrogen organic bases and ammonium
cations. No figures were presented with respect to efficiency or cost.
A French patent has been granted for the removal of boron from dis-
charged process waters by fixation, in the form of boric acid, on an an-
ionic ion-exchange resin followed by elution with alkali•£?/ A test solu-
tion, originally containing 2,600 ppm boron, showed 151 ppm after one run
through the resin. Recycling the effluent reduced the boron concentration
to 47 ppm. No information was presented for solutions containing low con-
centrations of boron («* 10* ppm) nor were any cost estimates included in
the abstract.
19
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No evidence was found to indicate that industry is currently using
these resins to remove boron, nor were any operating costs found in the
literature.
Adsorption on Clay Materials
It has been reported that boron may be adsorbed by certain clay ma-
terials from water—:./ but three montmorillonite micas and one bentonite
clay were tested with water containing 10 ppm boron and none were found
to remove boron ..iZ/
Distillation of Boron Containing Waters
A process has been patented for removal of boron from water by dis-
tillation of a liquid waste containing 21,000 to 22,000 ppm boron*2i
The distillate still contained 50 to 80 ppm of boron. Upon passing the
distillate through a 6-ft bed of ceramic Raschig contact rings, the boron
content was reported to have been reduced to 2 to 3 ppm boron*=/ No cost
estimates were reported for this process.
Although no indication was found of any current use in industry, the
process has potential application in the decontamination of nuclear re-
actor coolants.
Alumina-Lime-Soda
The alumina-lime-soda water treatment process was developed as a
unique method for softening brackish water, especially those containing
major quantities of calcium and magnesium sulfate, prior to desalination
in a reverse osmosis system. An important bonus of this process is its
ability to remove boron and other ions from brackish water. Raw water,
doped with 1.7 ppm boron, was treated by this process and the posttreat-
ment water was found to contain 0.2 ppm boron. Both lime and sodium alu-
minate are required to achieve boron removal as neither constituent alone
will remove this component.
Unit costs for a system designed to remove boron, and estimated on a
basis similar to that used for costing ion-exchange systems, would be
$0.20 to $0.25/1,000 gal. for a 1 MGD plant*M/
Ion-Exchange Resin Produced by Condensation of Catechol and Formaldehyde
In the work done by Roberts et al.,—' it was thought that an ion-
exchange resin produced by the condensation of catecho1 and formaldehyde
could be effective in removing boron from irrigation return waters. This
was based on the fact that the formation constant for catechol-basic boric
acid complexes is very large. The desired physical properties of the product
20
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resin were not met in their experiments and the resin did not effectively
remove boron from the test solution. No recent literature has appeared in-
dicating that an ion-exchange resin of this type has received further
attention.
Gomplexation of Boron and Rejection by Reverse Osmosis
In the work by Roberts et al., it was suggested that boron may be
complexed with water soluble organic polyhydroxy compounds to form a
molecular species which, due to size and ionic character* .would tend to
be membrane impermeable in the reverse osmosis process.— In these
studies, the six materials tested as possible complexing agents were:
mannitol, fructose, polyvinyl alcohol, tartaric acid, catechol, and a
soluble starch. Only catechol proved to be reasonably effective in boron
reduction. For a test solution containing 10 ppm boron, catechol showed
an effectiveness of about 70%. All other materials showed an effective-
ness in the range of 30 to 45% with the same test solution. Since these
particular studies considered only systems with an effectiveness of /** 90%
to be acceptable, no further studies relating to cost or other factors
were undertaken.
A recent study has presented cost analyses for the reverse osmosis
treatment of brackish water and seawater*^' For a 3 million gallon per
day (MGD) operation using a hard water feed and a 95% water recovery,
the cost was $0.77/1,000 gal. These figures are based on 1972 dollars.
The membranes were of the hollow fiber (Permasep®) type. Based on the
rapidly advancing technology of reverse osmosis and cost estimates for
the new operation to be based at Yuma, Arizona, it was estimated that
future costs for brackish water treatment would be approximately $0.36 to
$0.37/1,000 gal. based on a 1,000 ppm inlet feed and a 90% rejection rate.
While this study was not directed specifically towards boron removal,
the projected costs should be applicable to its removal. For an initial
boron concentration of the order of 10 ppm, the cost of the catechol
(based on 40 ppm) to be added during the pretreatment process would re-
sult in a cost of $0.45 to $0.75/1,000 gal., depending upon the quality
of the catechol. Current prices for catechol are $1.35/lb (tech grade)
and $2.25/lb (CP grade).
A cellulose acetate butyrate (GAB) reverse osmosis membrane has been
developed and preliminary research indicates a better rejection rate of
uncomplexed boron, as boric acid,—' than the more conventional cellulose
acetate (CA) membrane. However, the flux, i.e., the amount of water per-
meating 1 sq ft of membrane per day, was considerably lowered.
21
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Following is a summary of the comparative results:~'
Flux (gal/ft2, % Boric acid
Membrane membrane/day) rejected
CA 26 18
GAB 8 53
The boric acid rejection of 53% is not considered an acceptable value in
most studies and feed solution had an initial concentration of 1,700 ppm
boric acid. Most of the studies reviewed indicate that approximately 80%
or more rejection is. considered acceptable. While this membrane could
make the problem of complete organic complexation less critical than with
the cellulose acetate membrane more generally used at the present time,
no studies have been conducted at concentrations of about 10 ppm of boron
to test the effectiveness of this system at those levels. No cost infor-
mation was stated for the CAB process.
Distillation Separation of the Methanol-Boron Azeotroper^
The possibility of separation of boron, in the form of borates, by
this method arises from the common analytical separation technique. In
this procedure, methanol is combined with an aqueous hydrochloric acid
solution containing the boron. The azeotrope, BCOCH^^-CHoOH, is distilled
from the original solution into water.
The azeotrope can then be hydrolyzed with excess base and the meth-
anol recycled by distillation. The boron remains in the second aqueous
solution and could be disposed as a solid by evaporation of the water.
Since this method is used for the quantitative determination of boron,
the efficiency would be expected to be high (•** 98%).
This separation procedure would be applicable only to streams con-
taining high boron loading, since the volume of distillate would be ex-
cessively large for the removal of small concentrations of boron. It is
possible that the method would be useful for process streams or other
instances of high boron concentration, but not for normal wastewater or
municipal sewage streams containing low boron concentrations. No cost
figures were found in the published literature.
Specially Prepared Active Carbon
A Japanese patent, Japan 74 37,035, outlined a method for preparing
activated carbon capable of adsorbing boron from waste or seawater*iZ/
The preparation of the carbon involved the following steps:
22
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1. Active carbon is added to a soluble salt or solution of iron.
2. The mixture is then hydrolyzed.
3. The insoluble iron hydroxides are consequently absorbed by or
deposited on the active carbon.
The above prepared substance adsorbs boron and other metal ions.
No costs or efficiencies were listed in the reference.
23
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REFERENCES FOR SECTION IV
!• Versar, Inc., Preliminary Investigation of Effects on the Environment
of Boron, Indium, Nickel, Selenium, Tin, Vanadium, and Their Com-
pounds, Vol. I, Boron, U.S. Environmental Protection Agency, EPA-
56/2-75-005A, Washington, D.C. (1975), NTIS No. PB 2459847AS.
2. Cox, M«, Process Engineer, Kerr-McGee Chemical Corporation, Trona,
California, personal communication to Mr. Gary Cooper, February
6, 1976.
3. Ottinger, R. S., J. L. Blumenthal, D. F. Dal Porto, G. I. Gruber,
M. J. Santy, and C. C. Shih, Recommended Methods of Reduction, Neu-
tralization, Recovery, or Disposal of Hazardous Wastes, Vol. XII,
NTIS PB-224 591, U.S. Department of Commerce, Springfield, Virginia
(1973).
4. Fluesmier, L*, Eagle-Picher Industries, Miami, Oklahoma, personal
communication to Mr. Gary Cooper, February 6, 1976.
5. Anonymous, "Waste Treatment Has Gone Continuous for Xerox," Chemical
Engineering, .74*98, January 16, 1967.
6. Cronin, J. L., Environmental Engineer, U.S. Borax and Chemical Cor-
poration, Wilmington, California, personal communication to
Mr. Gary Cooper, February 11, 1976.
7. Dickert, C., Rohm and Haas Company, Philadelphia, Pennsylvania, per-
sonal communication to Mr. Gary Cooper, January 26, 1976.
8. Personal communication, Mr. Henry Ongirth, Chief Sanitary Engineer,
State of California Department of Public Health.
9. Personal communication, Mr. Thomas Bailey, Director of Research,
California State Water Resource Control Board, Sacramento,
California.
24
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10. Personal communication, Mr. Khairy Aref, Division of Planning and
Research, California Water Resource Control Board, Sacramento,
California.
11. Wood, D. K., G. Tchobanoglous, "Trace Elements in Biological Waste
Treatment," J. Water Pollution Control Federation, T^l^'.l-WS-
1945, July 1975.
12. Lunt, H. A., Digested Sewage Sludge for Soil Improvement, The
Connecticut Agricultural Experiment Station, Bulletin 622, New
Haven, Connecticut (1959).
13. Waggott, A., "An Investigation of the Potential Problem of Increasing
Boron Concentration in Rivers and Water Courses," Water Research,
.3:749-765 (1969).
14. Banerji, S. K., B. D. Bracken, B. M. Garg, "Effect of Boron on Aero-
bic Biological Waste Treatment," Proceedings of the 23rd Industrial
Waste Conference, Engineering Extension Series No. 132, Purdue
University (1968).
15. Hermann, E. R., "A Toxicity Index for Industrial Wastes," Industrial
and Engineering Chemistry, jn(4) :84A-87A, April 1959.
16. Kunin, R., "A Macroreticular Boron-Specific Ion-Exchange Resin,"
Trace Elements in the Environment, Advances in Chemistry Series,
No. 123, E. L. Kothney, Ed., American Chemical Society, Washington,
D.C. (1973).
17. Roberts, R. M., and L. E. Gressingh, Development of Economical Methods
of Boron Removal From Irrigation Return Waters, Research and Develop-
ment Progress Report No. 579, U.S. Office of Saline Water, U.S. De-
partment of the Interior, U.S. Government Printing-Office, Washington,
D.C. (1970).
18. Grinstead, R. R., and R. M. Wheaton, Improved Resins for the Removal
of Boron From Saline Water - Exploratory Study, Research and Develop-
ment Progress Report No. 721, Office of Saline Water, U.S. Depart-
ment of the Interior, Washington, D.C. (1971).
19. Ottinger, R. S., J. L. Blumenthal, D. F. Dal Porto, G. I. Gruber,
M. J. Santy, and C. C. Shih, "Boric Acid," in: Recommended Methods
of Reduction, Neutralization, Recovery or Disposal of Hazardous
Waste, Vol. XII, PB-224 591, U,S. Environmental Protection Agency,
National Technical Information Service, Springfield, Virginia (1973).
25
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20. Technical Bulletin IE-153-68, Amberlite® XE-243, Rohm and Haas Com-
pany, Philadelphia, Pennsylvania, October 1974.
21. Patterson, J. W., and R. A. Minear, "Treatment Technology for Boron,"
Wastewater Treatment Technology, 2nd ed., PB-216 162, Illinois
Institute for Environmental Quality, National Technical Information
Service, Springfield, Virginia (1973).
22. Grinstead, R. R., "Removal of Boron and Calcium from Magnesium Chlor-
ide Brines by Solvent Extraction," Industrial and Engineering Chem-
istry, Product Research and Development, llj(4): 45 4-460 (1972) and
references contained therein.
23. Chemical Week, August 16, 1972.
24. Chemical and Engineering News, p. 44, October 7, 1963.
25. Anonymous, "Patent Tells More About Boron Extractants," Chemical
and Engineering News, 42(3):40-41, January 20, 1964.
26. Personal communication, Robert R. Grinstead.
27. Fletcher, A. W., "Metal Extraction From Waste Materials," Chemistry
and Industry, pp. 776-780, July 10, 1971.
28. Chemical Information Services, 1975 Directory of Chemical Producers,
United States of America, Stanford Research Institute, Menlo Park,
California (1975).
29. Peterson, W« D., (Occidental Petroleum Corporation), U.S. Patent
3,856,670; CA, 83, 102888b (1975).~
30. Chauvet, P., and Y. Berton, French Patent 2,058,618; CA, 7&9 49638x
(1972).
31. Doeldner, R. W., (to Aqua-Chem, Inc.), U.S. Patent 3,480,515; CA, 72_,
27486m (1970).
32. Nebgen, J. W., E. P. Shea, and S. Y. Chiu, "The Alumina-Lime-Soda
Water Treatment Process,"Office of Saline Water, U.S. Department
of the Interior, Washington, D.C. (1972).
33. Personal communication, J. W. Nebgen and A. D. McElroy, Midwest
Research Institute, Kansas City, Missouri.
34. Channabasappa, K. C., Desalination, j^7:31 (1975).
26
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35. Manjikian, S., L. Liu, M. Foley, C. Allen, and B. Fabrick, "Develop-
ment of Reverse Osmosis Membranes," Research and Development Pro-
gress Report No. 534, Office of Saline Water, U.S. Department of
the Interior, Washington, D.C. (1970).
36• Gallery Chemical Company, Boron Hydrides and Related Compounds, 2nd
ed., report prepared for the Department of the Navy, May 1954.
37. Sugasaka, K., et al., Japan Patent 74 37,035; CA, 8£, 129025 (1975).
27
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TECHNICAL REPORT DATA
(Please rend Instructions on the reverse before completing)
1. REPORT NO.
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Chemical Technology and Economics in Environmental
Perspectives; Task II - Removal of Boron From Waste-
Waf
5. REPORT DATE
June 1976
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Thomas W. Lapp and Gary R. Cooper
8. PERFORMING ORGANIZATION REPORT NO.
Task II
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
Contract No. 68-01-3201
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Protection Agency
Office of Toxic Substances
Washington, D.C. 20460
13. TYPE OF REPORT AND PERIOD COVERED
Final, February - March, 197
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The purposes of this study were to determine the degree of general concern re-
garding the presence of boron in industrial waste streams and municipal sewage sys-
tems and to ascertain if any industries or cities are currently engaged in the re-
moval of boron from their wastewater. For those methods currently practiced, the
specific method of removal, effectiveness, and cost estimates were determined. The
current literature was surveyed for other methods of boron removal that may have
merit for future application in this area. Efficiency of boron removal and cost
estimates were presented for several of the possible methods. A survey of the litera-
ture was also conducted to determine the effect of boron on microorganisms present in
municipal waste treatment systems.
7.
KEY WORDS AND DOCUMENT ANALYSIS
a.
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Berates
Borax
Boric acids
Boron oxides
Industrial waste treatment
S ewage
Chemistry
Inorganic Chem-
istry
8. DISTRIBUTION STATEMENT
Release Unlimited
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
27
20. SECURITY CLASS (Thispage.)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
28
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