United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/S2-91/036 Sept. 1991
^ EPA Project Summary
Effect of Bromide on Chlorination
Byproducts in Finished Drinking
Water
Hossein Pburmoghaddas
Whenever natural water or humic sub-
stances are chlorinated, significant con-
centrations of trihalomethanes (THMs)
and haloacetic acids (HAAs) are pro-
duced. Bromide concentration In raw
water is a significant factor in the forma-
tion of chlorinatlon byproducts in fin-
ished drinking water. To investigate the
role of bromide ion concentration on
formation and speciation of non-THM
chlorinatlon organic byproducts, a two-
block, full-factorial matrix was designed
to statistically evaluate the influence of
various parameters that are relevant to
drinking water treatment. The first block
used a high chlorine dose and the sec-
ond block used a low dose. The factorial
design Incorporated one factor (bromide
[Br"]) at four levels and two factors (time,
pH) at three levels for each block. Over
1,600 experimental observations of the
chlorination organic byproducts moni-
tored in this study were evaluated.
The study determined the range of
concentration of nine HAAs, four THMs,
and three dihaloacetonitrlles (DHANs)
produced under different experimental
conditions. The percent of total organic
halogen (TOX) attributed to HAAs, THMs,
and DHANs, was determined for each as
a group as well as for individual THMs
and HAAs. Almost all of the independent
variables were positively correlated with
formation of HAAs, THMs, DHANs, and
TOX. Br*, in chlorinated humlcacid solu-
tion, was shown to shift the distribution
of THMs, HAAs, and DHANs to more
bromlnated species. As with THMs In the
presence of bromide, both brominated
species and species containing bromine
(Br) and chlorine (Cl) (bromochloroacetic
acid [BCAA]), dichlorobromoacetlc acid
[DCBAA], dibromochloroacetlc acid
[DBCAA]) were formed forthe haloacetic
acids. The resu Its of this study show that
the percentage of TOX, made up of total
THMs plus total HAAs, significantly in-
creased With increasing pHand bromide
concentration. These observations sug-
gested that a higher concentration of
bromide and a higher pH caused the
formation of mainly bromlnated THMs
and HAAs, which can be Identified and
quantified by the current method. The
study of the three main groups of chlori-
nation byproducts indicated that THMs
are the largest class of chlorination
byproducts detected on a weight basis.
The HAAs were found to be the second
largest portion of the TOX in drinking
water at high pH.
This Project Summary was developed
by EPA's Risk-Reduction-Engineering
Laboratory, Cincinnati, OH, to announce
key findings of the research project that
Is fully documented In a separate report
of the same title (see Project Report
ordering Information at back).
Introduction
To control chlorination byproducts other
than THMs in drinking water/more informa-
tion is required to understand the factors
influencing their formation. One such factor
is the presence of certain inorganic chemi-
cal species in the source water. For ex-
ample, the effect bromide has on THM
formation and THM speciation principally
dependson concentration of that ion. Hence,
the presence or absence of other organic
byproducts of chlorination may also depend
on the bromide ion concentration in the
Printed on Recycled Paper
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water. Bromide may actually substitute for
Cl, producing Br-containing homologs of
the more familiar chlorine species.
Since bromide serves as a precursor in
someof the brominated organic byproducts
and probably affects the formation of some
of the nonhalogenated byproducts, it is im-
portant to understand its effect upon the
formation of these byproducts. The pro-
posed research was aimed at predicting the
non-THM chlorination byproducts and their
spociation based on the concentration of
bromide ion in water. A predictive model for
the organic byproducts would allow ma-
nipulation of water quality at the watertreat-
ment plant and allow for more ready compli-
ance with proposed standards.
Bromide can entersource waters through
natural or anthropogenic processes. Natu-
ral mechanisms include geologic sources
and saltwater intrusion of aquifers. Bromide
may also appear as a trace impurity in CI2
used for water disinfection.
Of equal consequence are sources of
bromide that relate directly to human activi-
ties. This category includes methyl bromide
and ethylene dibromide. Methyl bromide is
widely used in agricultural applications to
fumigate crops and soil. Once in the soil,
methyl bromide breaks down into inorganic
forms that are subsequently leached out
Into natural waters via agricultural run-off.
Ethylene dibromide is a common additive
to leaded gasoline. Methyl bromide, a deg-
radation product, is converted to inorganic
forms before its transport to natural waters.
Anothersource of bromide sometimes found
in urban run-off is rock salt used to deice
roads. Other bromine-containing com-
pounds can enter water through sewage
and industrial effluents. Bromide is present
in sea water at a concentration of 65 mg/L.
Once bromide is present in source water,
there are no known economical treatment
techniques available for removing it. The
current list of byproducts targeted for regu-
lation contains brominated and mixed bro-
mine-chlorine species of THMs and HANs.
These are known to form in bromide-con-
taining waters when chlorinated.
It was expected that analogous mixed
halo- and bromoacetic acids might also
form.Totestthis hypothesis, phenol, which
gives a high yield of trichloroacetic acid
(TCAA) as a percentage of TOX, has been
chlorinated in the presence of bromide ion
under typical formation potential reaction
conditions. Given the qualification that sev-
eral of the haloacetic acid standards were
not available and that some reference mass
spectra were not available, interpretation of
the data indicate that DCBAA, DBCAA,
BCAA, and tribromochloroacetic acid
(TBAA) are all formed. The same array of
products has since been seen when humic
acids are chlorinated under similar condi-
tions. The data indicate that the
monobromoacetic acid (MBAA) and mixed
haloacetic acids probably merit regulatory
consideration for consistency with THM and
DHAN precedents.
The objectives of this research were to:
1. Investigate the effect of bromide ion
concentration on the formation and
speciation of certain chlorination
byproducts other than THMs.
2. Identify the formation of haloacetic
acids containing Br and Cl under dif-
ferent bromide-ion concentrations and
quantify them.
3. Evaluate the relationship of these or-
ganic Byproducts with TOX.
4. Determine some of the conditions re-
quired to control the formation of non-
THM chlorination organic byproducts
resulting from the disinfection process
with bromide present.
Procedure
In this experiment, Super-Q water con-
taining commercial HA (Fluka)* was used
as the principal model system. The study
was performed in two blocks of samples.
Forthe first block, a high chlorine dose of 25
mg/L was used. Forthe second block, a low
CI2 dose of 11.5 mg/L was used. The inde-
pendent variables were pH, bromide, and
reaction time. The three levels of pH used
were 5,7, and 9.4. The pH range of 7 to 9.4
is typical of treated waters at softening and
coagulation plants before chlorination. The
fourbromide levels studied were 0,0.5,1.5,
and 4.5 mg/L as Br". The three reaction
times were 6,48, and 168 hr. All of the tests
were conducted at 25°C.
A two-block, full-factorial design was used
to accomplish this study. The use of a full-
factorial design allowed for.the effects of
each variable to be evaluated with accuracy
and precision. The factorial design further
allowed for detection of the main and inter-
action effects of the variables. The factorial
design incorporated one factor (Br") at four
levels and two factors (time, pH) at three
levels for each block. A computer program
(SAS) was used for statistical analysis. The
Harvard Graphics software package was
used for plotting the formation curves, and
Lotus 1,2,3 was used for the calculations.
'Mention of trade names or commercial products does
not constitute endorsement or recommendation for
Experiments were conducted to deter-
mine the percent recoveries of the HAAs
using the TOX method. Two concentra-
tions, high and low, and triplicate samples
were used.
Results and Discussion
Br" in chlorinated HA solution has been
shown to shift the distribution of HAAs to
more brominated (DBAA, TBAA) and mixed
halogenated (BCAA, DCBAA, DBCAA) spe-
cies.
Although TCAA and DCAA are the princi-
pal halogenated organics other than THMs
in the absence of bromide ion, these com-
pounds decrease rapidly in a manner simi-
lar to trichloromethane (TCM) with the in-
cremental addition of bromide ion. This study
also revealed that for the HAAs, the bromi-
nated and mixed species would" I5e~the"
dominant components in the presence of a
high bromide ion concentration.
The analysis-of-variance (ANOVA) tests,
run to compare the effects of high and low
CI2doses, showed no significant differences
in the relative concentration of individual
HAAs (except for the mixed halogenated
acetic acids BCAA, DCBAA and DBCAA).
The concentration of each of these three
byproducts was significantly less atthe lower
chlorine dose. All tests were conducted at
0.05 level of significance.
There were significant interactions among
the various parameters that influenced
byproduct concentrations.
Thefull report was submitted in fulfillment
of Work Assignment No. 01-2W130, T&E
Contract No. 68-03-4038, by the University
of Cincinnati under sponsorship of the U.S.
Environmental Protection Agency.
•fru.S. GOVERNMENT PRINTING OFFICE: 1991 - 548-028/40058
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Hosseln Poumoghaddas was with the University of Cincinnati, Cincinnati, OH 45221.
Ronald C. Pressman is the EPA Project Monitor (see below).
The complete report, entitled "Effect of Bromide on Chtorination Byproducts in Finished
Drinking Water," (Order No. PB91-217919; Cost: $23.00, subject to change) will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Monitor can be contacted at:
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental
Research Information
Cincinnati, OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use $300
EPA/600/S2-91/036
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