EPA 908/3-77-001
JANUARY 1977
FORMATION AND REMOVAL
OF HALOGENATED
HYDROCARBONS
IN DRINKING WATER
A CASE STUDY AT HURON,
SOUTH DAKOTA
US. ENVIRONMENTAL PROTECTION AGENCY
REGION VIII
DENVER , COLORADO 8O295
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EPA Report No. 908/3-77-001
January 1977
FORMATION AND REMOVAL OF HALOGENATED
HYDROCARBONS IN DRINKING WATER
A Case Study at Huron, South Dakota
By
Leland L. Harms
Robert W. Looyenga
South Dakota School of Mines § Technology
Rapid City, South Dakota 57701
R008128010
Project Officer
Jack W. Hoffbuhr
Control Technology Branch
Water Division
U.S. Environmental Protection Agency
Denver, Colorado 80295
This study was conducted
in cooperation with
South Dakota School of Mines § Technology
Rapid City, South Dakota 57701
REGION VIII
U.S. Environmental Protection Agency
Denver, Colorado 80295
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DISCLAIMER
This report has been reviewed by the Region VIII, U.S.
Environmental Protection Agency, and approved for publication.
Approval does not signify that the contents necessarily re-
flect the views and policies of the U.S. Environmental Pro-
tection Agency, nor does mention of trade names or commercial
products constitute endorsement or recommendation for use.
11
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FORWARD
One of the many challenges facing communities and the Environmental
Protection Agency is to assure the provision of safe drinking water. This
task is complicated by the variety of contaminants entering our water
sources. During the past few years, over 180 organic chemicals have been
identified in drinking water across the United States. A group of these
compounds known as the trihalomethanes, are formed when chlorine reacts
with organic substances found naturally in most surface waters. This is
of concern since chlorine is the principal disinfectant used for treating
drinking water. A nation-wide EPA study of 80 cities in 1975 revealed
that Huron, South Dakota's drinking water had one of the highest concen-
trations of trihalomethanes encountered.
In an effort to assist the community with this problem, we funded
the project described by this report. As a result of the study, the
trihalomethane concentration in the Huron water supply was greatly reduced,
Also, this research has helped to expand our knowledge on the formation
of trihalomethanes and the techniques to reduce their concentrations in
drinking water.
We express our appreciation to the South Dakota School of Mines,
the City of Huron and the South Dakota Department of Environmental
Protection for their cooperation and assistance with the project.
A. Green
//Regional Administrator
111
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ABSTRACT
Samples were collected from the water treatment process
at Huron, South Dakota. These samples were tested for the
same six organic compounds used by EPA in a recent survey of
drinking waters.
High levels of chloroform and bromodichloromethane were
found to be formed during the treatment process. The haloform
reaction was found to be very pH dependent and changing the point
of application of the prechlorine dose reduced chloroform in
the effluent by 75%.
Total haloforms in the drinking water could be lowered
further if the effluent pH could be lowered to a near neutral
pH. Additional aftergrowth of the chlorinated hydrocarbons
occurred in the distribution system.
This report was submitted in fulfillment of Grant No.
R008128010 by the South Dakota School of Mines and Technology
under the sponsorship of the U. S. Environmental Protection
Agency. This report covers a period from August 15, 1975 to
August 15, 1976 and work was completed as of January 31, 1977.
IV
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CONTENTS
Foreword iii
Abstract iv
Figures vi
Tables vii
Abbreviations and Symbols viii
Acknowledgement ix
1. Introduction 1
General 1
Objectives 2
Scope of Work 2
2. Conclusions 3
3. Recommendations 4
4. Background Literature 5
5. Huron, S. Dak. Municipal Water Treatment Plant.10
General 10
Treatment 11
6. Methods 13
Field 13
Laboratory 15
Apparatus 15
Instrumental Parameters 15
Reagents 16
Analytical Procedures 16
7. Results 17
Initial Data 17
Monitoring 21
pH Effects 28
Temperature Effects 28
Stability Studies 32
Variations in the Distribution System . . 33
Operating Experience 35
Disinfection with Chloramines 36
8. Future Work 38
References 4o
Appendix 42
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FIGURES
Number Page
1 Process Flow Diagram for Water Treatment 14
2 Relocation of Prechlorination Dose 20
3 Potential Versus Actual Chloroform Formation
After Chlorination Change 23
4 Portion of Chloroform Formed by Prechlorine
Dose 24
5 Bromodichloromethane Formation After
Chlorination Change 26
6 Portion of Bromodichloromethane Formed By
Prechlorine Dose 27
7 Effects of pH on Chloroform Formation 29
8 Chloroform Reduction By Lowering Effluent pH .... 30
9 Bromodichloromethane Relationship to pH in Clear Well 31
VI
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TABLES
Number Page
1 James River Water Quality 10
2 Chemical Feed Rates for September 8, 1975 12
3 Initial Data For Trihalomethane Formation 17
4 Trihalomethane Formation Without Prechlorination. . 19
5 Trihalomethane Formation After Relocation of the
Prechlorination Dose 21
6 Median Trihalomethanes During Monitoring Period . . 22
7 Temperature and Haloform Variations at Sta. 7
During June 32
8 Raw Water Quality at Huron, South Dakota 33
9 Haloforms Within the Distribution System 34
10 Effects of Chlorination Revisions
on Chlorine Dose 36
11 Savings from Chlorine Revisions 37
Al Haloform Data 43
VII
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ABBREVIATIONS
EPA
MGD
ppm
ppb
GC
MS
GAG
LIST OF ABBREVIATIONS AND SYMBOLS
-- United States Environmental Protection Agency
-- Million gallons per day
-- part per million
-- part per billion
-- Gas Chromatograph
-- Mass Spectrophotometer
-- Granular Activated Carbon
SYMBOLS
CHCU
CHCl2Br
yg/1
-- Chloroform
-- Bromodichloromethane
-- microgram per liter
Vlll
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ACKNOWLEDGEMENTS
The interest and cooperation given by the administrative
officials of Huron, South Dakota is gratefully acknowledged.
We would particularly wish to express our thanks to the Huron
City Council; Mr. Glenn Housiaux, City Engineer; and Mr.
Harold Root, Water Treatment Plant Superintendent.
Technical assistance with the instrumentation was given
by Dr. A. A. Stevens of the Municipal Environmental Research
Laboratory, U.S. Environmental Protection Agency, Cincinnati,
Ohio.
Bacteriological testing was conducted in the laboratories
of the South Dakota Department of Environmental Protection.
IX
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SECTION 1
INTRODUCTION
General
Within the last three years, public attention has again
focused on the water it consumes as being a possible health
hazard. The scrutiny given to the New Orleans public water
supply by the national media is an example of this attention.
With cancer as a major cause of death in the United States, it
is not easy to disregard the small concentrations of the many
compounds which may be present in drinking water supplies.
In an attempt to gain some indication as to the magnitude
of the problem, EPA conducted an 80 city survey in which the
raw and treated drinking waters were examined for six organic
compounds. The six organic compounds selected were the four
trihalomethanes; chloroform, bromodichloromethane, dibromo-
chloromethane, and bromoform; as well as 1, 2 - dichloroethane
and carbon tetrachloride. The concentrations of these com -
pounds ranged from zero to trace amounts in the raw waters, but
they were wide-spread in the finished waters. Results of the
survey indicate that the formation of these compounds is caused
by the chlorination practices normally followed during water
treatment operations (1).
Results of the survey (1) showed that chloroform was de-
tected in the finished water of 100% of the cities surveyed,
and that bromodichloroethane was found in 97.5% of the finished
waters. Huron, South Dakota had the dubious distinction of
having the highest concentration of bromodichlor-omethane
(116 yg/1) as well as the second highest concentration of
chloroform (309 yg/1 compared to a high value of 311 yg/1).
Although a definite correlation between the rate of human
cancer and the concentrations of the organics in the drinking
water did not exist, it was thought to be prudent to reduce
these concentrations as much as possible. Consequently a
study was carried out at the Huron Water Treatment Plant and
the results are reported herein.
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Objectives
The objectives of the study were:
(1) To qualitatively and quantitatively analyze the
Huron water supply to more precisely define the
problem of contamination by chloroform and other
related halogenated hydrocarbons.
(2) To establish the source of these compounds.
(3) To find a means of water treatment which would
effectively reduce the concentrations of these
compounds.
Scope of Work
All the field work was conducted in the City of Huron,
South Dakota. Samples were collected from the on-line facility
which serves the citizens of Huron. Samples were not taken
from pilot plant facilities or other microscale operations.
Initial monitoring of the plant operations began in
February, 1976. Modifications to the treatment scheme were
tried on an experimental basis in March, and some permanent
changes were implemented in late April, 1976. From May until
August, 1976, extensive sampling was conducted to determine
the effects of in-plant modifications. Additional bench-scale
experiments were also carried out at this time.
Analytical work was performed on campus at the South Dakota
School of Mines and Technology laboratories. Some initial field
measurements were made on the samples in the laboratory at the
Huron Municipal Water Treatment Plant.
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SECTION 2
CONCLUSIONS
The investigation at Huron has provided valuable in-
sight into the formation of haloforms under actual water
treatment practices. The following conclusions were drawn
from the study:
1. The haloforms form during and after water
treatment. They were found to form in high
concentrations at the point of chlorination
and lime addition.
2. The potential chloroform concentration at
Huron remains high, in the range of 200 to
325 ppb. However, the relocation of the pre-
chlorination dose to a point following re-
carbonation resulted in a significant reduction
in the chloroform concentration.
3. The mechanism of chloroform formation is
strongly pH dependent, and the chloroform con-
centration in the clear well closely follows the
effluent pH.
4. Lowering of the effluent pH below 9 is limited
by problems of water stability-
5. Haloform concentrations continue to rise after
entering the distribution system.
6. The ultimate solution to the problem of halo-
form formation is precursor removal, but a
more practical solution is to prevent their
formation during the treatment process.
7. The mechanism of bromodichloromethane form-
ation does not appear to be strongly pH depend-
ent .
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SECTION 3
RECOMMENDATIONS
Recommendations which evolved from the study are:
1. The disinfection should continue at the revised
location.
2. Additional data on bromodichloromethane formation
should be gathered. This constituent was not
significantly reduced in this study.
3. Additional work should be done on the aftergrowth
of haloforms within the distribution system.
4. Identification of the precursor source(s) should
be considered in an attempt to reduce the potential
for chlorinated hydrocarbon formation. Possibilities
to be evaluated should include:
a. point sources upstream
b. the local practice of disposing of dead
animals in the stream
c. precursor increase from biological growth
in stagnant water
d. agricultural runoff as a precursor source
5. Alternate methods of disinfection should be con-
sidered such as the use of ozone, chloramines and
chlorine dioxide.
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SECTION 4
BACKGROUND LITERATURE
The National Organics Reconnaissance Survey (NORS) was
conducted by EPA in late 1974 and the spring of 1975 (3). The
objectives of the survey were to monitor the concentrations of
four specific trihalomethanes, to determine the effects of raw
water sources and water renovation practices on the formation
of these compounds and to determine the organic content of the
drinking water supplied to cities in different parts of the U.S.
From this survey came several conclusions. These conclusions
dealt with relationships of nonvolatile total organic carbon
and trihalomethane concentrations, the occurrence of trihalo-
methanes in precipitation softening treatment plants, relation-
ships of chlorine residual and trihalomethane concentrations
and correlations between the use of ozonation, powdered activated
carbon, granular activated carbon and lower trihalomethane con-
centrations. One of the study's major conclusions was that the
four halomethanes were "widespread in chlorinated drinking waters
in the U.S. and result from chlorination."
The work of J. J. Rook and Bellar, Lichtenberg and Kroner
innovates the mechanics of haloform reactions (4),(5). The
major emphasis of the work by Rook deals with the type of organic
precursors that contribute to haloform formation, such as meta-
hydroxy aromatics as well as dihydroxy chlohexane, the con-
ditions favorable to haloform formation, precursor removal by
macroreticular resin adsorption, chlorination combined with
ozonation and removal of halogenated organics by activated carbon
adsorption and air stripping (4).
The work of Bellar, Lichtenberg and Kroner includes a con-
densed overlook of a GC-MS method for the identification of
volatile organics and conclusions based on their research in this
field of study. Possible contamination by lab chloroform of
water samples to be tested for halofonns, the results of surface
and other water supplies monitoring and some of the chlorinating
procedures used in treatment plants that contribute to haloform
concentrations are some of the conclusions discussed (5).
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An extensive overlook of different types of methods for the
determination of the organic substances in water supplies that
give rise to such characteristics as color, odor and taste was
published in a 1967 edition of the ASCE Journal (6). The methods
reviewed include adsorption onto carbon, liquid-liquid extraction
counter-current extraction, freeze concentration, distillation,
visual range spectroscopy, infrared spectroscopy, ultraviolet
spectroscopy, mass spectroscopy, gas-liquid chromatography, paper
chromatography, thin-layer chromatography and the use of a carbon
analyzer.
A more recent analytical method for the isolation and de-
termination of volatile organics in drinking water is offered by
Bellar and Lichtenberg (7). A combination of gas-Chromatography,
mass-spectrometry is described including an extensive depicture
of the types of materials used in the analysis. Simplified, the
procedure consists of adsorption onto a solid sorbent and the
separation and detection of the concentrations of the volatile
organics.
Another, newer method of gas chromatographic analysis uses
acetylated XAD-2 resins, pyridine and a small pre-column of
copper (II) chloride (8). This procedure makes it possible to
get better detection limits and shows better resolution into
haloform peaks than previous methods.
In a March 1975 report, Morris and McKay (9) reviewed the
mechanics of the formation of halogenated organics in water
supply. The principal points in this study are: ways chlorinated
organics are introduced into the water supply, the haloform
reaction, the precursors to haloform formation and several treat-
ment modifications to reduce haloform concentrations.
The authors cite four principal routes for chlorinated
organics to enter into water supply. These four methods are non-
point sources, industrial discharges, chlorination of sewage
or industrial wastewater and the chlorination of organic matter
in drinking water. Some of the chlorine-containing compounds
(found in water supplies) consist of fungicides, pesticides,
polychlorinated biphenyls, and haloforms.
Haloform reactions, according to the authors, usually take
place in an aqueous, alkaline solution. The types of substances
most likely to react to form a haloform are organic compounds
with an acetyl group or compounds with a group easily oxidized
to an acetyl group, such as acetaldehyde and ethanol. A se-
quence of seven reactions take place to form a haloform. The
first of these reactions, and the slowest, is the initial dis-
sociationof a positively charged hydrogen to yield a carbanion.
The following reactions leading to the end-product of a haloform
all proceed at essentially the same speed.
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The precursors to haloform reactions in natural, unpolluted
waters stem from organic matter whose source is plant life. High,
molecular weight humic substances, such as fulvic acids, con-
tribute to the chlorine demand of the water. The high, chlorine
demand of water has been linked with significant haloform con-
centrations. Low, molecular weight carboxylic acids are common
in water supply in the several milligram per liter range. The
more complex carboxylic acids yield to hypochlorite reactions
forming haloforms. The simple, aliphatic monocarboxylic acids
are relatively nonreacting with hypochlorite.
Two approaches to the control of haloform concentrations in
drinking water supplies are emphasized. The first method is the
removal of as much of the precursor as possible, the second is
to remove the byproducts of chlorination after they are formed.
The techniques for accomplishing the first method are: the dis-
continuation of prechlorination, storage of water for several
months, coagulation-filtration, ozonation, potassium perman-
ganate treatment or combinations of these. Procedures for the
second approach include adsorption onto activated carbon and
aeration techniques (9).
Bench-scale and pilot plant operations dealing with granular
activated carbon filters and ozonation for the control of tri-
halomethanes are some of the main points in an EPA report (10).
Briefly, the pilot plant studies consist of the removal of tri-
halomethanes from treated tap water with GAG filters, and fil-
tration by GAG filters after conventional pretreatment which
was subsequently followed by chlorination, or chlorination and
ozonation. The principal trihalomethanes tested for were chloro-
form, bromodichloromethane, dibromochloromethane and bromoform.
In the first pilot plant experiment, coal-base and lignite-
base GAG filters were tested over specific time periods for
the percentage reduction of chloroform and bromodichloromethane.
Tap water from Cincinnati, Ohio was applied with the chloroform
range from 34-72 ug/1 and the bromodichloromethane range of
8-20 yg/1 concentrations. After 4 weeks, the coal-base GAG
filter showed about a 4070 chloroform removal, whereas the lignite-
base showed approximately an 8070 removal. Similar results were
obtained for bromodichloromethane. Because the two carbons were
subjected to different loadings, it can not be definitely stated
that the lignite-base GAG is superior. However, the researchers
did conclude that: "The trend of the data from the lignite-base
GAG would indicate that its ability to remove chloroform was
somewhat greater than the coal-base material" (10).
In the next study, Ohio River water was coagulated, settled
and then filtered by one of three different methods, and finally
chlorinated or chlorinated and ozonated. The types of filters
used were (a) dual media (sand/coal), (b) coal-base GAG, (c) dual
media followed by coal-base GAG. Summarizing the results, ozo-
7
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nation and chlorination of the effluents from filter No. 1
actually caused an increase in the chloroform concentration, but
a decrease in the bromodichloromethane over a 6 day period. How-
ever, the same treatment of effluents from filters No. 2 and 3
did not substantially affect the amount of chloroform, bromo-
dichloromethane or dibromochloromethane over a 6 day period. The
total range of the concentrations of the trihalomethanes in this
specific experiment were from .2 to 15 yg/1, and no bromoform
was found in any of the samples tested.
Also, from this study came several conclusions based on
chlorination of raw and different types of treated water from
the Ohio river. The first of,these conclusions states that when
enough chlorine is added to satisfy the chlorine demand of the
raw water, seven times the amount of chloroform is formed then
when filtered effluent of a dual media filter is chlorinated.
When the water was filtered on a fresh coal-base GAG filter and
chlorinated, only one-eightieth of the amount of chloroform was
formed. Secondly, chloroform has been found to have the most
significant concentration in the water samples, followed by
bromodichloromethane and dibromochloromethane in the ratio of
100:15:1. Thirdly, the water samples tested with the higher
chlorine demand had the highest trihalomethane concentrations.
It was concluded, furthermore, that both inorganic and organic
chlorination byproducts were formed, since it was discovered
that only 37o of the chlorine added went into the trihalomethanes.
Lastly, it was found that as long as there was a chlorine re-
sidual measured, there was a trihalomethane concentration (10).
A recently published study measured halogenated methanes
in Iowa finished waters. Concentrations of the haloforms were
compared with turbidity values for some samples. A correlation
between river turbidity and chloroform seemed to be indicated.
Minimum recorded values of 45 and 55 yg/1 chloroform occurred
at low flow conditions while the high of 230 yg/1 chloroform
was recorded at the highest turbidity. The authors concluded
that: "the upper Midwest agricultural belt is the major upstream
contributor of halogenatable organic runoff to the Mississippi
River system and that all downstream users are affected by this
non-point source discharge" (11).
At this point in time, no one presumes to have all the
answers which are necessary to be certain that the organics prob-
lem in drinking water is under control. EPA has set this tone in
a July issue of the Federal Register in which they discussed the
options available for the control of organic contaminanants (12).
They expressed concern for the possible health hazard created by
these compounds, and invited public comment regarding the regu-
latory questions discussed.
Current thinking on treatment modifications to control the
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trihalomethanes is given in a recent document released by EPA (13)
the discussion includes precursor removal by the use of granular
activated carbon and the prevention of chloroform formation by
using alternate means of disinfection. A main disadvantage to
the use of carbon beds is the limited time before the adsorption
capacity of the carbon is expended. Alternate disinfectants such
as ozone, chlorine dioxide, and chloramines are being considered.
All the methods have both advantages and disadvantages. Work
is currently underway to further define when these methods are
applicable.
Water treatment at Huron, South Dakota is described in de-
tail in the next section. The water treatment process employs
lime softening so the chlorination occurred at a high pH level.
The quality of the raw water is quite variable, and the pre-
sence of organics has been a frequent problem. A very recent
study, published after the work reported herein was concluded,
addresses this combination of variable water quality and high
pH (14) . Stevens and his EPA coworkers used bench and pilot-
scale projects to investigate the effects of precursor concen-
trations, pH, type of disinfectant and temperature on trihalo-
methane formation. The results obtained at the full-scale
treatment plant at Huron confirm some of the conclusions Stevens
et al drew from their bench scale studies, specifically regard-
ing the importance of the point of location of chlorination in
the treatment process, and the additional trihalomethane pro-
duced at the higher pH levels.
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SECTION 5
HURON SOUTH DAKOTA MUNICIPAL
WATER TREATMENT PLANT
General
Huron's municipal water supply is the James River, a small
slow-moving stream which flows through eastern South Dakota.
The water quality is extremely variable as shown in Table 1.
Agricultural runoff, upstream wastewater discharges, dead ani-
mals disposed in the stream, and seasonal variations all combine
to make the raw water difficult to treat for domestic use.
According to the operator's log at the treatment plant, the
river water pH usually falls within a range of from 7.5 to 8.5.
TABLE 1.
Constituent
Total solids, ppm
Total hardness, ppm
Iron, ppm
Calcium, ppm
Chloride , ppm
Sulphates , ppm
Bicarbonates , ppm
Fluorides , ppm
Nitrates , ppm NO-
Magnesium, ppm
Sodium, ppm
Potassium, ppm
JAMES RIVER WATER
Raw Water
Low
271
131
0.02
53
51
100
98
0.3
0.3
33
29
14
QUALITY (2) .
High
2180
963
0.05
158
157
785
812
0.4
2.0
119
352
25
Average
547
256
-
-
-
167
248
-
-
-
80
-
10
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Treatment
Water treatment at Huron consists of chemical addition,
sedimentation, flocculation, clarification, recarbonation,
filtration and chlorination. A process schematic is shown
in Figure 1. A more detailed process description follows:
Process step
River to plant
Initial chemical addition
Presedimentation
Prechlorination
Rapid Mix No. 1
Flocculation
Clarification
Recarbonation
Gravity filters
Postchlorination
Description
Raw water is pumped from an
intake located about 100'
upstream from a small dam.
Rapid dispersion of potassium
permanganate, activated carbon
alum, and a polyelectrolyte
(Nalco 607) .
Settling of about 1 hour dur-
ation at a flow of 6 MGD.
Initial chlorine dose, approxi-
mately 6 to 7 mg/1. Point of
application revised during study
period.
Chemical dispersion of lime,
soda ash (occasionally) , and
sodium aluminate (Nalco 617) .
Gentle stirring of the water-
chemical mixture. Detention
time at 6 MGD is about 1.5 hours
Settling of slightly more than
2 hours at a flow of 6 MGD.
^ to
Fluoride
Adjustment of pH with
obtain a stable water.
for the control of dental caries
and polyphosphate (Nalco 918)
are added at this basin. The
prechlorination dose was moved
to this location in late April
1976.
Filtration process using antra-
filt media.
A final chlorine dose for dis-
infection.
11
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Process step Description
Clearwell storage Short term water storage
at the treatment plant.
Chemical feed rates vary from day to day depending upon
the initial water quality and the plant operation. Average
daily use values of from 1 to 3 MGD are common with peak day
demands approaching 7 MGD having been recorded. Chemical feed
rates for 9/8/75 are shown below in Table 2. Flow on this
date was about 2.5 MGD.
TABLE 2. CHEMICAL FEED RATES FOR SEPTEMBER 8, 1975
Chemical Feed Rate, mg/1
Prechlorine dose 6.8
Postchlorine dose 2.6
Carbon 2.2
Soda ash 0
Lime 152
Alum 29
Sodium Aluminate 9.6
(Nalco 617)
Fluoride 1.2
Stabilizer 2.0
(Nalco 918)
Potassium permanganate 0.98
Polyelectrolyte 0.80
(Nalco 607)
Carbon dioxide 36
12
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SECTION 6
METHODS
Field
In order to locate the source(s) of formation of the halo-
forms, a series of seven sampling sites closely tracing the pro-
gress of water treatment at the Huron plant were selected.
These sampling locations are indicated by station number on
Figure 1. They are:
Station 1 - Raw water intake to the treatment plant.
Station 2 - Effluent from presedimentation tank.
Station 3 - Effluent from rapid mixer.
Station 4 - Effluent from flocculation tank.
Station 5 - Effluent from sedimentation tank.
Station 6 - Above gravity filters.
Station 7 - Clear well.
Once the sites were chosen and the sampling procedures es-
tablished, the samples were collected by Mr. Larry Doss, our
field engineer in Huron. The samples were collected and sealed
bubble free in 60 ml glass bottles, packed in ice, and sent by
air express to the laboratory. On arrival at the laboratory,
the samples were stored in a refrigerator at about 5 C until
analyzed, normally on the following day-
It should be noted that no reducing agent was added to
the samples to stop the action of chlorine and the correspond-
ing formation of haloforms. While there may be some disadvan-
tages in allowing the reaction to proceed, this does allow for
establishing which stage(s) of the treatment process have
conditions favorable for haloform formation. By allowing the
reaction to proceed for a minimum of 24 hours the results give
an indication of the potential haloform concentration under the
existing conditions. Packing the samples in ice protected them
from temperature extremes during shipment. While it was diffi-
cult to precisely control the time between sample collection and
analysis, results of previous work suggested little or no in-
crease in haloform concentration after 15 hours of contact with
chlorine (5). It might also be noted that the sample handling
procedures are in close agreement with those used in the National
Organics Reconnaissance Survey (3).
13
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KMn04
. ALUM
CARBON
CHLORINE PRIOR
TO 4/76 I
JAMES
RIVER
V
r
t
v
\
POLYELECTROLYTE PRESEDIMENTATION
LIME
SODA ASH
SODIUM
ALUMINATE,
FLOCCULATION
SEDIMENTATION
RAPID
MIX NO. I
CHLORINE FLUORIDE
AFTER 4/76 I poLYPHOSPHATE
t
POSTCHLORINATION
\
1
f
1
ANTHRAFILT
GRAVITY
i
C02 FILTERS
RECARBONATION
TO STORAGE
AND CITY
250,000
GALLONS
CLEAR WELL
Figure 1. Process flow diagram for water treatment.
14
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Laboratory
Apparatus
The basic apparatus used in this study consisted of a
Varian Model 705 Gas Chromatograph fitted with a modified in-
let system, a Tracer Model 310 Hall Electrolytic Conductivity
Detector, and a Varian Model A-25 strip chart recorder. Ad-
ditional apparatus included a purging device, trap, and de-
sorber system, all of which were constructed after those de-
scribed by Bellar and Lichtenberg (7). The trap was con-
structed with an appropriate fitting to enable it to be
coupled directly to the injection port of the G.C. Thus, the
injection port heater of the G.C. served as the heat source
for desorption, and the regular carrier gas flow served to
sweep the desorbed gases onto the column. A separate helium
gas line and flow control valve were installed for backflush-
ing (desorbing) the trap.
The various instrumental parameters used in the study
follow.
Instrumental Parameters
Purging Device
Purging Gas ------------ He, 20 ml/min
Trap (1/8" x20cm ------ Packed with 60-80
meshTenax GC
Desorption
Desorption Gas- ---------- He, 20 ml/min
Trap Temp. ---------------- 180° C
Column Temp.- --------------- 30° C
Gas Chromatograph
Column
Construction - - - - 6mm x 10 ft glass column
Packing -------- 60/80 mesh Tenax GC
Carrier Gas ------------ He, 20 ml/min
Temperature Program o
Preisothermal hold ----- 14 min at 95 C
Program ---------- 8°/min to 180° C
Transfer line (glass lined)- ----- 200 C
Detector
Electrolyte ------------1 ml/min
Reaction Gas --------- -R , 10 ml/min
Furnace Temperature- --------- 820 C
Attenuter- --------------- 16 x
Conductivity -------------- 3x
Recorder --_______;[ mv, 0.5 cm/min
15
-------
.Reagents
All solutions were prepared, when possible, from reagent
grade chemicals.
Organic free water was prepared by purging 5 ml of dis-
tilled water with inert gas (He) for 11 min. at 20-30 ml/min.
Stock Standard Solutions. Standards of CHClo and CHCl2Br
were prepared in methanol at 100 and 500 ppm using a 10 yl
syringe and 50 ml volumetric flasks. Further dilutions with
methanol were made as required. All standard solutions were
refrigerated when not in use.
Working Standard Solutions. Working standards were pre-
pared by adding the appropriate volumes of stock standards to
5 ml of purged distilled water.
Analytical Procedures
Before analyzing any samples the trap was conditioned by
placing it in the inlet port of the gas chromatograph and flush-
ing with helium at 20 ml/min and 180° C for 4 min. Following
conditioning of the trap a blank and two standards were run in
order to check instrument response and calibration.
Once the instrument was calibrated, the samples were ana-
lyzed as follows:
1. Place the sample bottle in a water bath at 20 C
and allow the temperature to equilibrate.
2. Using a 5 cc glass hypodermic syringe, transfer
5 ml of sample to the purging device.
3. Attach the trap to the exit port of the purging
device and purge the sample for 11 min with helium
gas at 20 ml/min.
4. Transfer the trap to the modified inlet port of
the gas chromatograph and backflush (desorb)
with helium at 20 ml/min at 180° C for 4 min.
5. Replace the trap with a plug, quickly raise the
column temperature to 95° C and start the recorder
6. Following 14 min at 95° C, program the column
temperature at 8° C/min to 180° C.
7. Following 5 min at 180° C, reduce the column
temperature to 30° C, or less, and proceed with
the next sample.
16
-------
SECTION 7
RESULTS
Initial Data
Initial data to better define the location of trihalo-
methane formation were collected in February 1976. Samples
were taken from several stations within the water treatment
plant and analyzed for the six organic compounds previously
discussed. These data are presented in Table 3 shown below.
TABLE 3. INITIAL DATA FOR TRIHALOMETHANE FORMATION
Date
2/10/76
2/23/76
2/10/76
2/23/76
2/23/76
2/10/76
2/23/76
2/10/76
2/23/76
2/10/76
2/10/76
2/10/76
PH
8
8
7.
7.
7.
11.
11.
11.
11.
11.
9.
9.
8
8
7
5
5
5
5
5
6
5
Station CHC13
1
1
2
2
(raw water)
(raw water)
(before pre-chlorination)
(before pre-chlorination
2A (between Cl~ and lime)
3
3
4
4
5
6
7
(lime addition)
(lime addition)
(post-flocculation)
(post-f locculation)
(post -clarification)
(post filter)
(clear well)
,yg/l CHCl2Br,Mg/l
a
a
5
8
145
203
180
208
175
215
176
210
a
a
a
a
34
22
13
14
6
10
35
42
a. Below detection limit of 0.1 yg/1
17
-------
Samples taken on both February 10th and 23rd clearly in-
dicate that both chloroform and bromodichloromethane form be-
tween Sta. 2 (presedimentation) and Sta. 3 (chemical addition).
Conditions were optimum for trihalomethane formation. Non-
sett leable precursors had not been removed, a chlorine dose had
just been added, and the pH of the solution was raised. The
other four compounds were not detected.
There are some additional items that should be noted re-
garding the data in Table 3. On both occasions, the organic
compounds were not detected in the raw water, but they were
formed as a result of the water treatment process. Specifi-
cally a reaction occurred between precursors and the chlorine
added to the water. Initial formation of chloroform is rapid,
and the concentration gradient was such that traces were de-
tected at Sta. 2, just before the chlorine was added. The
formation of bromodichloromethane did not appear to be as
rapid a reaction. Once formed, the concentrations were of the
same order of magnitude throughout the remainder of the treat-
ment process. For example, the chloroform concentration was
about 200 yg/1 after lime was added.
Previous work has established that the haloform reaction
proceeds rapidly in alkaline aqueous solutions (9). There-
fore, it seemed prudent to attempt to chlorinate at lower pH
levels.
Data in Table 4 reflect the trihalomethane concentrations
formed when the prechlorination dose was temporarily dis-
continued, but while the normal post chlorination was con-
tinued. Both chloroform and bromodichloromethane concen-
trations were substantially reduced as seen by the concen-
trations recorded at Stations 5 and 6. The increase evident
in samples collected from the clear well, Sta. 7, results from
the relatively short time that the prechlorination step was
interrupted. At this time, it was not known what changes in
bacterial quality could be anticipated when the prechlorination
dose was not being used. Therefore, the clear well was not
adequately flushed and the water in the clear well contained
a mixture of high and low level organics.
18
-------
TABLE 4. TRIHALOMETHANE FORMATION WITHOUT PRECHLORINATION
Date
3/1/76
3/1/76
3/1/76
3/1/76
3/1/76
3/18/76
3/18/76
3/18/76
3/18/76
3/24/76
3/24/76
3/24/76
3/24/76
3/24/76
PH
8
7
11
11
9
7
11
7
8
8
11
10
7
7
.1
.7
.1
.8
.1
.7
.6
.1
.3
.8
.6
.4
Site CHCl3,Mg/l
1
2
3
5
7
1
5
6
7
1
3
5
6
7
(raw water)
(before pre-chlorination)
(lime addition)
(post -clarification)
(clear well)
(raw water)
(post filter)
(post filter)
(clear well
(raw water)
(lime addition)
(post clarification)
(post filter)
(clear well
a
a
3
8
111
a
a
17
73
a
a
a
5
25
CHCl2Br,yg/l
a
a
a
a
23
a
a
3
20
a
a
a
0.3
10
a. Below detection limit of 0.1 yg/1.
Having thus established that eliminating the prechlorin-
ation step would result in lower trihalomethane formation, it
became necessary to establish what affect this procedure had
on the overall water treatment process. In the Huron plant,
the prechlorination step was primarily used to lengthen filter
runs between washings.
It was decided to move the prechlorination dose to the
recarbonation basin. This new location still allowed the
chlorine to be applied prior to the, filters, but after the pH
had been lowered. The relocation is shown in Figure 2.
Initial results from moving the point of chlorine appli-
cation are given in Table 5. Extra water samples were collected
19
-------
(V\
L_
KMnQ4
. ALUM
CARBON
JAMES
RIVER
PUMPS
CHLORINE PRIOR
TO 4/76 I
POLYE LECTROLYTE RRESEDIMENTATION
LIME
SODA ASH
SODIUM
ALUMINATE,
t (?i (5) »#
^ \.v - - \±/
. ^* _^-0
k /^ °^C
\^S FLOCCULATION
S°
RAPID
MIX NO.
SEDIMENTATION
CHLORINE FLUORIDE
I AFTER 4/76jpOLYpHospHATE (?)
ANTHRAFILT
POSTCHLORINATION
C02
RECARBONATiON
GRAVITY
FILTERS
©
TO STORAGE
AND CITY
250,000
GALLONS
CLEAR WELL
Figure 2. Relocation of prechlorination dose.
20
-------
from various locations within the distribution system and
both chlorine residual and total coliforms were determined
on these samples. No adverse effects were noted. The
obvious benefits of this change resulted in the permanent
relocation of the chlorine dose.
TABLE 5. TRIHALOMETHANE FORMATION AFTER
RELOCATION OF THE PRECHLORINATION DOSE
Concentration in Clear Well
Sampling Date
4/28/76
5/4/76
5/14/76
5/20/76
5/26/76
PH
7.9
8.0
9.1
9.2
9.2
CHC13> yg/1
35
40
58
99
69
CHCl2Br, yg/1
4
12
6
11
4
Monitoring
Additional monitoring of the system was carried out for
2 months following the relocation of the prechlorine dose.
Samples were collected from Stations No. 1, 3, 5, 6 and 7. A
portion of the sample from Station 3 was chlorinated with
sodium hypochlorite, designated as sample 3a, and treated
identical to the samples collected from other stations. This
sample was used to approximate the concentrations of trihalo-
methanes which would have been formed in the treatment process
if the prechlorination step had not been moved.
Samples from Sta. 5 were adjusted to pH 7 (redesignated
as 5a) and hypochlorite was added. This sample represented
the trihalomethanes formed at a near neutral pH. It was not
feasible to operate the treatment plant at this pH for reasons
of water stability. This will be more fully discussed later.
Table 6 shows the median values for chloroform and bromo-
dichloromethane from a set of 12 samples collected during
June and July. Throughout this period only chloroform and
bromodichloromethane were detected of the six organic para-
meters considered. The mean percent reduction for chloroform
during this period was 75%, but the effluent bromodichloro-
methane concentration actually was higher than anticipated.
It appears that the bromodichloromethane forms at a slower
rate (compare Stations 3a, 6, and 7). This is not the complete
story, however, as in 10 of the 12 samples tested, the bromo-
2 1
-------
dichloromethane concentration is higher at Sta. 5a than at
Sta. 3a. This phenomenon is more noticeable later in the
report and will be discussed in more detail at that time.
TABLE 6. MEDIAN TRIHALOMETHANES DURING
MONITORING PERIOD
Station Median CHC13> yg/l Median CHCl2Br, yg/l
1
3
3a
5a
6
7
a
a
230
30
32
57
a
a
2
6
1
9
a. Below detection limit of 0.1 yg/l.
Figure 3 shows the actual chloroform delivered to the
distribution system (Sta. 7) when compared to the potential
chloroform which would have been given to the consumer if the
prechlorination dose had not been moved from after presedimen-
tation to the recarbonation basin (See Figure 2). The mean
chloroform concentration was 222 yg/l for samples collected at
Sta. 3 and adjusted by hypochlorite addition (Sample 3a).
Mean chloroform found in the clear well during this period
was 59 yg/l. The reduction obtained was approximately 75%.
The results obtained at Sta. 6 are compared to Sta. 7 in
Figure 4. Samples from Sta. 7 were used to obtain the chloro-
form concentrations contributed to the distribution system,
while the samples from Sta. 6 can be used to illustrate the
portion furnished by the prechlorination dose. Approximately
50% of the chloroform in the plant effluent was produced by
the chlorine added just prior to filtration. Although vari-
ables such as pH, temperature, reaction time, and precursor
concentration could not be controlled, the authors believe
that the reaction at Sta. 6 is limited by the amount of chlor-
ine added at this location. Chlorine residuals were run on
the samples after determining the trihalomethanes and were
found to be zero or near zero in all cases for Sta. 6. The
mean chloroform concentration at Sta. 6 was about 30 yg/l.
22
-------
cc
o
o
330
270
210
50
90
30
0
POTENTIAL CHLOROFORM
TO SYSTEM
-
STA. 3, CHLORINE ADDED (3d)
ACTUAL CHLOROFORM TO
DISTRIBUTION SYSTEM
. o
X> O i
^STA. 7
JUNE
JULY
SAMPLING DATE
Figure 3. Potential versus actual chloroform formation after chlorination change
-------
0>
cc
o
o
i
o
80
60
40
20
0
STA. 7 - CHLOROFORM TO
DISTRIBUTION SYSTEM
STA. 6 - PORTION FORMED FROM
PRECHLORINE DOSE
JUNE
JULY
SAMPLING DATE
Figure 4. Portion of chloroform formed by prechlorine dose.
-------
An interesting item to note is that prior to the relocation
of the prechlorine dose, that prechlorination accounted for
almost 100% of the chloroform in the plant effluent. For ex-
ample on 2/10/73 the chloroform concentration at Sta. 3, just
after prechlorination, was 203 yg/1 (See Table 3); and the
chloroform concentration in the plant effluent was 210 yg/1.
The astute reader may wonder how the present reaction at
Sta. 6 could be chlorine limited when previously there was
adequate chlorine available to allow for the formation of over
200 yg/1 of chloroform. One of the side benefits to moving
the prechlorine dose was a reduction in the amount of chlorine
used. For example, initially chlorine was added on 9/8/75 at
a dose rate of 6.8 mg/1 for the prechlorine dose and 2.6 mg/1
for the postchlorination step. On 6/2/76 these same two rates
were 1.6 mg/1 and 2.9 mg/1, respectively. Thus, there was a
76% reduction in the amount of chlorine available to react with
precursors during the prechlorination stage.
Figures 5 and 6 show the general trends for bromodichloro-
methane during the monitoring period. Comments on Figure 6
which compares the concentration of bromodichloromethane at
Sta. 6 with Sta. 7 would seem to be generally the same as those
given for Figure 4, i.e., that the reaction at Sta. 6 is
chlorine limited and that the concentration at Sta. 6 repre-
sents the portion of the final bromodichloromethane discharged
to the distribution system. However when the combined data
on both figures are compared, the answers do not appear to
be simple ones.
For example, Figure 5 which compares concentrations of
bromodichloromethane at Sta. 3a and Sta. 7 gives some interest-
ing results. The effluent concentration is much higher than
that formed at the intermediate sampling station. The
samples from Sta. 3 were artificially chlorinated with sodium
hypochlorite while the on-stream samples from Sta. 7 were
chlorinated with chlorine gas. This should not be a factor,
however, because elemental chlorine is almost completely
hydrolyzed to HOC1 and OC1~ at a very rapid rate (9). It is
known that the bromodichloromethane reaction proceeds slowly
for several days (8), but the difference in detention time
would be only a few hours and would not appear to be an ex-
planation.
Original dibromochloromethane concentrations in the
plant effluent were in the 15 to 42 yg/1 range. The values
for Sta. 7 in Figure 5 do not reveal a substantial reduction
for this constituent as a result of moving the prechlorina-
tion dose. It has been documented that both temperature and
pH affect the haloform concentrations (4) (14). The major
factor within the plant at Huron seems to be one of pH ad-
justment and is the reason for the results stated. A discus-
sion of pH effects follows.
25
-------
UJ
o
(T
O
O
Q
O
S
O
o:
QD
36 -
30
24
8
0
JUNE
ACTUAL BROMODICHLORO-
METHANE TO DISTRIBUTION
SYSTEM
STA. 7
STA. 3, CHLORINE
ADDED
JULY
SAMPLING DATE
Figure 5. Bromodichloromethane formation after chlorination change,
-------
X
I-
LU
O
CC
O
_l
X
O
Q
O
O
tr
CD
STA. 7- BROMODICHLOROMETHANE
TO DISTRIBUTION SYSTEM
STA. 6-PORTION
FORMED FROM
PRECHLORINE
DOSE
0
SAMPLING DATE
Figure 6. Portion of bromodichloromethane formed by prechlorine dose
-------
p_H__Effects_
The influence of pH on chloroform concentration was docu-
mented by J. J. Rook in a laboratory study (4). His data showed
a significant increase in chloroform concentration between pH 7
and pH 10, with the rate of increase becoming very rapid at
the higher pH value. Similar conclusions can be drawn from
the data shown in Figure 7. These data were collected from
a full-scale treatment process. The points scatter somewhat
about the regression line, but several critical parameters
such as temperature, chlorine dose rate, precursor concen-
tration, and detention time were not controlled, as would be
expected in a field investigation of this type.
These data indicate that a chloroform concentration of
only about 40 yg/1 would be formed if the water was recarbon-
ated to a pH of 7 before chlorination. If other variables
were under control in the field, it might be possible to lower
the effluent concentration of chloroform to approximately
20 yg/1 (See the dashed line, Figure 7 which eliminates the
points of widest scatter). This speculation is confirmed by
the data shown in Figure 8. Samples were taken from Sta. 5
(after sedimentation) and chlorinated after the pH had been
adjusted to 7. As seen in the graph, the chloroform formed
was about 20 to 40 yg/1 which substantiates the previous data
given in Figure 7. Efforts to reduce the plant effluent to a
lower pH are reported in the section on water stability. The
initial sample at Sta. 5 had a chloroform concentration of 90
yg/1 which seems much too high when compared with the remain-
ing data. All the samples were grab samples so some fluctua-
tions were to be expected, but this particular value should
be viewed with suspicion.
It has been noted in a previous section that a substan-
tial reduction was not obtained in bromodichloromethane con-
centrations by relocating the prechlorination dose. The
primary reason for gaining the reduction in chloroform con-
centration was the effect of pH on this concentration, as
discussed above. Figure 9 shows a plot of the bromodichloro-
methane concentrations in the clear well against the pH of
the clear well. From the scatter of the data points, it is
obvious that pH has a minor affect on the bromodichloro-
methane concentration. Thus, changing the location of the
prechlorination dose did not substantially affect the con-
centration of this constituent.
Temperature Effects
Although the effect of temperature on chloroform for-
28
-------
100
80
_ 60
o>
cr
o
u.
o
tr
3 40
x
o
20
0
STA. 7
CLEAR
WELL o
ACTUAL EFFLUENT
ESTIMATED POTENTIAL
CHCI3= 11.57 pH-39.72
o
7.0
Figure 7
8.0
9.0
10.0
pH, units
Effects of pH on chloroform formation.
29
-------
cc
o
u_
o
u> cc
0 o
_l
X
o
80
60
40
20
0
STA. 7 - ACTUAL CHLOROFORM
TO DISTRIBUTION SYSTEM
STA. 5- ADJUSTED TO pH 7,
CHLORINE ADDED
JUNE
*-*-
JULY
SAMPLING DATE
Figure 8. Chloroform reduction by lowering effluent pH.
-------
36 -
30
D>
^
UJ
2
<
I
o
cc
o
o
Q
O
IE
O
cr
00
8 -
0
7.0
8.0
9.0
10.0
pH, units
Figure 9. Bromodichloromethane relationship to pH in clear well
-------
mationhas been documented (14), no noticeable temperature
effect was shown at the Huron Water Treatment Plant. Tern-
peiature was a minor variable during the monitoring period,
and the temperature changes were probably masked by other
variables such as pH and precursor concentrations. The follow-
ing table gives temperature, and chloroform and bromodichloro-
methane values for Sta. 6 (clear well) during June. No
correlation with temperature is noted.
TABLE 7. TEMPERATURE AND HALOFORM
VARIATIONS AT STA. 7 DURING JUNE
Date
°
Temperature, C
CHC13, ng/1
CHBrCl2, ug/1
6/1/76
6/7/76
6/9/76
6/14/76
6/17/76
6/20/76
6/23/76
6/27/76
20.5
23.0
25.0
23.0
20.0
21.0
21.0
21.5
40
53
69
45
55
80
41
57
6
5
9
<2
29
33
8
7
Stability Studies
The information previously presented regarding pH effects
indicates that it would be desirable to have the effluent pH
near 7, because pH 7 appears optimum for chloroform control.
However, the water treatment process used at Huron uses lime
for softening. Good treatment practices dictate that the lime
softened water be recarbonated so that a thin film of calcium
carbonate is deposited in the distribution system pipe net-
work. The thin layer of scale is useful in retarding corrosion
and helps prevent "red water" complaints.
Stability control of the finished water at Huron is based
on several years of good experience using the Ryznar Sta-
bility Index (15) . This index gives a pH of approximately 9
for the lime softened water. Reducing the finished pH to a
lower value to prevent chloroform formation would result in
an aggressive or corrosive water. This, of course, would not
32
-------
be acceptable.
Originally when recarbonation was used to lower the pH of
a water after softening, the idea was to convert all the re-
maining carbonates to bicarbonates. Final pH would then be
about 8.3. Actual practice soon found that a water thus
treated was aggressive, not stable. Investigation of this pro-
blem^was made using the Langelier Saturation Index, the Ryznar
Stability Index, and the well known marble test. The con-
clusion was that the final effluent as currently produced at
Huron was stable and that the pH of the final effluent should
not be lowered unless the softening process was altered.
The main problem with lime softened water is the low
alkalinity remaining after softening, and the tendency for
this water to dissolve scale and precipitates in an attempt
to increase the alkalinity. Several bench scale softening ex-
periments were conducted in an attempt to use soda ash with or
without lime to leave a higher alkalinity while still obtain-
ing a soft water for the consumer. Presently the raw water
at Huron is such that only lime is required to produce a
satisfactorily softened water. No satisfactory results which
could be recommended for full-scale application were forth-
coming from the softening experiments, and these studies were
abandoned.
Future changes in the raw water quality at Huron might
be cause for reconsideration of the chemical dosages for soft-
ening. The raw water quality at Huron during the period of
this study is given in Table 8. The interested reader is re-
ferred to other selected readings for a more detailed cover-
age of this problem (16) (17) (18) (19).
TABLE 8. RAW WATER QUALITY AT HURON, SOUTH DAKOTA
Total Hardness,Calcium Hardness,Total Alkalinity,
Date mg/1 CaC03 mg/1 CaC03 mg/1 CaC03 pH
9/15/75
12/11/75
3/15/76
5/12/76
5/30/76
6/3/76
224
252
420*
260
232
232
136
140
232
112
120
156
256
240
360
228
180
220
8.6
7.9
7.4
8.3
8.1
7.8
"'Maximum hardness observed in one year's records
Variations in the Distribution System
The National Organics Reconnaissance Survey (1) examined
33
-------
raw and finished waters of 80 cities and did not inspect changes
which may have occurred within the distribution system. For
the most part, the study reported herein did likewise. The
initial work was heavily concentrated on the haloform form-
ations which took place within the treatment process. Samples
were not dechlorinated on site, and it was assumed that the
values for Sta. 7 (clear well) represented about the concen-
trations which were delivered to the consumer.
The data presented in Table 9 were obtained from the
stations given below on samples that were dechlorinated in
the field with potassium ferrocyanide because the use of
sodium thiosulfate is thought to interfere with haloform de-
terminations (21). It can be seen that the concentrations
within the distribution system are not synonymous with those
of Sta. 7.
Sta. 7 - Clear well at water treatment plant,
not dechlorinated in the field.
Sta. 8 - Masonic Building in downtown Huron,
medium residence time.
Sta. 9 - Riverside Park near water plant,
short residence time.
Sta. 10- Airport near dead end in distribution
system, long residence time.
TABLE 9. HALOFORMS WITHIN THE DISTRIBUTION SYSTEM
Date
7/5/76
7/11/76
7/18/76
7/25/76
Station
7
8
9
10
7
8
9
10
7
8
9
10
7
8
9
10
CHC13, Mg/1
56
99
122
128
62
106
152
153
62
T40
115
146
96
142
79
118
CHCl2Br, yg/1
9
24
24
29
25
38
43
37
25
57
44
47
0
48
22
29
34
-------
This data in Table 9 indicate that the concentrations of
the haloforms fluctuate in the distribution system, and they
are higher than recorded at the plant effluent. This is im-
portant because it is the concentration at the tap which is
the cause for concern. Residence time in the distribution
system is not the entire answer, and a host of factors such
as precursor level, temperature, effluent pH, and available
chlorine need to be evaluated. This is a significant pro-
blem that requires additional study.
Operating Experience
The foregoing information documents the advantages gained
by relocating the prechlorination dose. This section of the
report reflects on the plant operation after the chlorine
was repositioned, April" to December 1976.
It was previously mentioned that the prechlorination
dose was primarily used to lengthen the filter runs between
washings'. Referring to Figure 1, the relocated pre-chlorine
dose remained prior to the gravity filters. To date (December
1976) , the operating personnel at the treatment plant have
not had to shorten the filter runs.
One might also suspect an increase in taste and odor
problems from biological growths in the now unchlorinated
portion of the plant. This problem has not been experienced
at Huron. However, those considering similar chlorination re-
visions at other water works facilities should consider the
possibility of taste and odor problems. Softening is prac-
ticed at the Huron treatment plant and the resulting high pH
discourages most biological metabolism.
Of obvious interest is a comparison of chlorine usage
before and after changing the point of chlorine application.
Table 10 gives the average chlorinator settings for both the
prechlorinator and the postchlorinator from April through
December of 1975 and 1976. The 1976 data represents chlorine
used after the point of chlorine application was changed,
while the 1975 data are for comparison only. It is not
possible to draw exact comparisons because the quality of
the raw water was variable. However, general trends should
be noted. During 1975 the majority of the chlorine was added
from the prechlorinator, and the postchlorine dose was about
1/3 of the prechlorine dose. However, during 1976, the pre-
chlorine dose was reduced by almost 75% and the postchlorine
dose had to be increased to maintain an adequate residual.
35
-------
TABLE 10. EFFECTS OF CHLORINATION
REVISIONS ON CHLORINE DOSE
Average Chlorinator Setting, Ib /day
Prechlorinator Postchlorinator
Month
April
May
June
July
August
September
October
November
December
1975
150
200
240
410
350
250
210
180
110
1976
50
60
70
90
80
70
60
50
50
1975
20
60
80
160
150
100
60
50
30
1976
70
90
150
210
210
180
160
110
90
Table 11 gives some indication of the savings obtained
from the in-plant chlorine adjustments. Average results are
a monthly savings of $215 (equivalent to one ton of chlor-
ine per month), a savings of about $2.08 per million gallons
processed. Again it should be remembered that these are
approximate comparisons because of the variations in the raw
water quality. Specifically the water became very difficult
to treat after July of 1976 because there was not any flow in the
James River. Additional planks were added to the 3rd Street Dam
to create a stagnant pool of river water from which the Huron
Water Treatment Plant withdrew its raw water.
Disinfection with Chloramines
It has been shown that it is the free chlorine that reacts
to form the haloforms during chlorination. Also, the use of
chloramines is known to result in a lower chloroform concen-
tration than would be produced using conventional chlorination
procedures (13). What is not known is the disinfecting capabil-
ities of the chloramines under field operating circumstances.
Some data exist which doubt the effectiveness of this agent (20).
Preliminary studies of some bench-scale experiments using
chloramines gave favorable results. Only low levels of both
chloroform and bromodichloromethane were detected. The results
are preliminary in nature as difficulties with the test were
encountered and disinfection was not considered, but the process
definitely warrants further study.
36
-------
TABLE 11. SAVINGS FROM CHLORINE REVISIONS
Water Processed, Total Chlorine Used Average C^Dose
Million Gallons/Month Ib/month nig/1
Month
April
May
June
July
August
September
October
November
December
1975
54.
66.
82.
140.
96.
73.
68.
47.
47.
785
666
160
945
165
478
807
861
585
1976
59.
92.
127.
124.
78.
73.
58.
46.
45.
953
577
403
658
116
448
732
765
780
1975
3038
5075
6349
13,671
9877
6216
4539
2626
1966
1976
2077
3162
5253
7094
5519
4494
3279
2241
2237
1975
6.
9.
9.
11.
12.
10.
7.
6.
4.
65
13
27
63
32
14
91
58
95
1976
4.
4.
4.
6.
8.
7.
6.
5.
5.
15
10
95
82
47
34
69
75
86
Average
, Net Savings,*
$Mo.
103.
205.
117.
707.
468.
185.
135.
41.
(-29.
215.
31
65
82
03
49
12
45
39
13)
01
$/MG
2.24
4.51
3.87
4.31
7.60
2.52
1.10
0.75
(-.81)
2.90
*Based on Chlorine @ $215/Ton
-------
SECTION 8
FUTURE WORK
Additional work at the Huron water works should be done
to further reduce the levels of haloforms delivered to the
consumer. It is believed by the authors that the more fruit-
ful approach is to attempt to prevent the halogenated hydro-
carbons from forming, as opposed to the removal of these com-
pounds after they have been formed. Possible procedures could
include:
1. Correlation of the raw water quality with the
trihalomethane formation in the treatment plant.
Data would need to be collected during runoff
events, and in general the surface supply
should be monitored for organic material,
solids, turbidity, and possibly some specific
precursors.
2. Additional investigate work on the distribution
system. It needs to be established whether the
increase in haloform concentrations within the
system is a time dependent problem or if addi-
tional precursors are added after the water
leaves the treatment plant.
3. Using chlorine dioxide for disinfection. Chlo-
rine dioxide is formed by onsite generation
using sodium chlorite.
2 NaC102 + C12 -* 2 C102 + 2 NaCl
The apparent advantage to the use of chlorine
dioxide is that it does not react with the same
materials in water that chlorine does and measur
able amounts of trihalomethane are not produced.
It also leaves a residual to be measured, an
advantage over ozone. A disadvantage is the
additional generating equipment needed. The
existing V-notch chlorinator can be used to
feed the chlorine, but a chlorine dioxide
generator and pump would need to be purchased.
Another disadvantage is that CICK is easily
removed from solution in open vessels. This
38
-------
may cause some problems in the point of
application. Also, the gas is extremely
explosive (22). There is some question re-
garding the toxicity of the chlorite formed by
the reduction of C102 (23). This hazard would
need to be more fully evaluated before appli-
cation to a full scale treatment process.
4. Ammonia addition. If ammonia is added along
with chlorine in the proper amounts, a com-
bined chlorine residual will result. The
combined residual is not as reactive as free
chlorine residuals with respect to trihalo-
methane formation. An ammoniator would be re-
quired for in-plant use, and the process would
need to be carefully monitored to be sure that
free residual chlorine was not formed in order
to keep trihalomethane formation to a minimum.
Some initial laboratory work to quantify the
disinfection capabilities of combined chlorine
residual would probably also be necessary, as
well as microbiological monitoring in the field
39
-------
SECTION 9
REFERENCES
1. "Preliminary Assessment of Suspected Carcinogens in Drink-
ing Water - Report to Congress." U.S. Environmental Pro-
tection Agency, Washington, B.C. (Dec. 1975).
2. "Report on Water Supply System and Proposed Improvements
for City of Huron, S.Dak." J. T. Banner and Assoc., Inc.,
Brookings, S.Dak. (May 1975).
3. Symons, J. M., et al., "National Organics Reconnaissance
Survey for Halogenated Organics." Jour. Amer. Water
Works Assn. , 67_, 634 (1975).
4. Rook, J. J., "Haloforms in Drinking Water." Jour. Ameri-
can Water Works Assn., 6_8, 168 (1976).
5. Bellar, T. A., e_t al. , "The Occurrence of Organohalides
in Chlorinated Drinking Waters", Jour. Amer. Water Works
Assn., 66, 703 (1974).
6. Baker, R. A., and Malo, B. A., "Water Quality Character-
ization-Trace Organics." Jour. San. Eng. Div. Proc.
Amer. Soc. Civil Engr. , 937~4T (Dec. T%7) .
7. Bellar, T. A., and Lichtenberg, J. J., "Determing Volatile
Organics at Microgram per Litre Levels by Gas Chromato-
graphy", Jour. Amer. Water Works Assn., 66; 703 (1974).
8. Kinssinger, L. D., and Fritz, J. S., "Analytical Notes-
Analysis of Drinking Water for Haloforms." Jour. Amer.
Water Works Assn. , 68^, 435 (1976).
9. Morris, J. C., and McKay, G., "Formation of Halogenated
Organics by Chlorination of Water Supplies." Office of
Research and Development, US EPA, Washington, D.C. (March
1975).
10. Love, 0. T., et al., "Preliminary Results of Pilot Plants
to Remove WateF Contaminants" in "Preliminary Assessment
of Suspected Carcinogens in Drinking Water, Interim Re-
port to Congress." USEPA, Washington, D.C. (June 1975).
40
-------
11. Morris, R. L., and Johnson, L. G., "Agricultural Runoff
as a Source of Halomethanes in Drinking Water." Jour.
Amer. Water Works Assn. , 6^8, 492 (1976).
12. "EPA Proposal on Control Options for Organic Chemical
Contaminants." Federal Register, 41, 28991 (July 14, 1976).
13. Symons, J. M. , et: al. , "Interim Treatment Guide for the
Control of Chloroform and Other Trihalomethanes."
Municipal Environmental Research Laboratory, USEPA,
Cincinnati, Ohio (June 1976).
14. Stevens, A. A., e_t al. , "Chlorination of Organics in
Drinking Water." Jour. Amer. Water Works Assn., 68,
615 (1976). ~~
15. Ryznar, J. W., "A New Index for Determining Amount of
Calcium Carbonate Scale Formed by a Water." Jour. Amer.
Water Works Assn. , 3_6 (April 1944) .
16. Langelier, W. F., "Chemical Equilibria in Water Treat-
ment." Jour. Amer. Water Works Assn., 38, 169 (1946).
17. Larson, T. E., "The Ideal Lime-Softened Water." Jour.
Amer. Water Works Assn., 43, 649 (1951).
18. Hoover, C. P., "Stabilization of Lime-softened Water."
Jour. Amer. Water Works Assn., 34. 1425 (1972).
19. Larson, T. E., "Corrosion by Domestic Waters." Bui.
No. 59, Illinois State Water Survey, Urbana (1975).
20. Kruse, C. W., et al., "The Enhancement of Viral In-
activation by Halogens." Water and Sewage Works, 118.
187 (June 1971).
21. Kopfler, F. C., et al., "GC/MS Determination of Valatiles
for the National Organics Reconnaissance Survey (NORS)
on Drinking Water." In "Identification and Analysis
of Organic Pollutants in Water," Ann Arbor Sci. Pub.
Inc., Ann Arbor, Mi. (1975).
22. White, G. C., "Handbook of Chlorination." Van Nostrand
Reinhold Co., New York, N. Y. (1972).
23. Myhrstad, J. A., and Samdal, J. E., "Behavior and Determin-
ation of Chlorine Dioxide." Jour. Amer. Water Works Assn.,
61, 205 (1969).
41
-------
SECTION 10
APPENDIX
Haloform Data
42
-------
TABLE Al. Haloform Data
UJ
Date
2/10/76
2/23/76
3/2/76
3/18/76
3/24/76
4/28/76
5/4/76
5/14/76
5/20/76
5/26/76
Parameter*
CHC13
CHBrCl2
CHC13
CHBrCl2
CHC13
CHBrCl2
CHC13
CHBrCl2
CHC13
CHBrCl2
CHC13
CHBrCl2
CHC13
CHBrCl2
CHC13
CHBrCl2
CHC13
CHBrCl0
2
CHC13
CHBrCl0
1
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
Sampling
6
ND
Sampling Station
2345
5 203 208 215
ND 22 14 10
8 180 175
ND 13 6
ND 3 8
ND ND ND
ND
ND
ND ND
ND ND
ND
ND
ND
ND
ND
ND
error
4
ND
6
175
35
15
18
5
<1
27
2
26
4
20
ND
8
1
7
210
42
111
73
25
10
35
8
40
12
58
2
99
69
4
-------
TABLE Al. Continued.
4>
Date
6/1/76
6/7/76
6/9/76
6/14/76
6/17/76
6/20/76
6/23/76
6/27/76
Parameter*
CHC13
CHBrCl2
CHC13
CHBrCl2
CHC13
CHBrCl2
CHC13
CHBrCl2
CHC13
CHBrCl2
CHC13
CHBrCl2
CHC13
CHBrCl2
CHC13
CHBrCl2
Sampling Station
1
9
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
3
5
ND
ND
ND
<1
ND
ND
ND
<1
ND
1
ND
<1
ND
ND
ND
3a
144
2
152
<2
144
ND
235
ND
230
6
230
10
230
5
210
<1
5a
90
6
27
4
29
<2
30
<2
18
10
35
9
37
8
14
2
6
21
3
32
2
40
<2
30
<2
25
9
38
7
22
4
26
ND
7
40
6
53
5
69
6
45
<2
55
29
80
33
41
8
57
7
-------
TABLE Al. Continued.
Ul
Sampling Station
Date
7/5/76
7/11/76
7/18/76
7/25/76
Parameter*
CHC13
CHBrCl2
CHC13
CHBrCl2
CHC13
CHBrCl2
CHC13
CHBrCl2
1
ND
ND
ND
ND
ND
ND
ND
ND
3
ND
ND
ND
ND
ND
ND
ND
ND
3a
288
<1
316
ND
264
33
-
ND
5a
28
6
-
36
15
34
6
6
33
<2
35
7
36
10
22
ND
7
56
9
62
25
62
25
96
ND
8
99
24
106
38
140
57
142
48
9
122
24
152
43
115
44
79
22
10
128
29
153
37
146
47
118
29
-All values given in yg/1
ND = Not Detectable
------- |