United States
Environmental Protection
Agency
Municipal Environmental Research EPA 600 2-79-060
Laboratory July 197 9
Cincinnati OH 45268
Research and Development
Ozone and
Ultraviolet Radiation
Disinfection for
Small Community
Water Systems
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REPORTING
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are
1. Environmental Health Effects Research
2. Environmental Protection Technology
3 Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6 Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-79-060
July 1979
OZONE AND ULTRAVIOLET RADIATION DISINFECTION
FOR SMALL COMMUNITY WATER SYSTEMS
by
Linden E. Witherell'
Ray L. Solomon
Kenneth M. Stone
Vermont State Health Department
Burlington, Vermont 05401
Contract No. 68-03-2182
Project Officer
Ralph W. Buelow
Drinking Water Research Division
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Municipal Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publica-
tion. Approval does not signify that the contents necessarily reflect
the views^ and policies of the U.S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.
11
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FOREWORD
The Environmental Protection Agency was created because of increasing
public and government concern about the dangers of pollution to the health
and welfare of the American people. Noxious air, foul water, and spoiled
land are tragic testimony to the deterioration of our natural environment.
The complexity of that environment and the interplay between its components
require a concentrated and integrated attack on the problem.
Research and development is that necessary first stop in problem
solution and it involves defining the problem, measuring its impact, and
searching for solutions. The Municipal Environmental Research Laboratory
develops new and improved technology and systems for the prevention, treat-
ment, and management of wastewater and solid and hazardous waste pollutant
discharges from municipal and community sources, for the preservation and
treatment of public drinking water supplies, and to minimize the adverse
economic, social, health, and aesthetic effects of pollution. This
publication is one of the products of that research; a most vital communi-
cations link between the researcher and the user community.
Replacing chlorination by the use of ultraviolet light and ozone as
sole disinfectants of small community water systems has been strongly
proposed by some but lacked sufficient actual experience to support this
proposal. This report presents a comparison of these disinfection pro-
cedures .
Francis T. Mayo, Director
Municipal Environmental Research
Laboratory
111
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ABSTRACT
This research was initiated to determine the applicability of using ozone
and ultraviolet light as disinfectants for small rural community water
systems. Parameters such as disinfection capability, operation and mainten-
ance requirements and costs were investigated and compared with a traditional
chlorination facility.
Existing water systems using Lake Champlain were retrofitted with either
ozonation or ultraviolet light disinfection equipment and operated for
periods of from 3 to 21 months. Specific data collected and summarized in
this report include coliform and standard plate count results for raw,
finished and distribution samples, capital and maintenance costs for ozona-
tors, ultraviolet light disinfection units, and sodium hypochlorite chemical
feed equipment and problems encountered with the equipment while it was in
operation.
This report was submitted in fulfillment of Contract 68-03-2182 by the
Vermont Department of Health under the sponsorship of the U.S. Environmental
Protection Agency. This report covers the period April 3, 1975 to December 3,
1977, and work was completed as of January 25, 1978.
IV
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CONTENTS
Disclaimer ii
Foreword iii
Abstract iv
Figures , vi
Tables vii
1. Introduction 1
2. Conclusions and Recommendations 3
3. Background Information 4
UV Radiation Disinfection 4
Ozone 6
4. Materials and Methods 9
UV Radiation Study 9
Ozone Disinfection Study 10
Chlorine Disinfection Study 10
5. Findings 11
South Hero Fire District #1 - Bacteriological Monitoring.il
Grand Isle Water Supply Company -
Bacteriological Monitoring 14
South Hero Fire District #2 - (North Shore System) -
Bacteriological Monitoring 17
Grand Isle Fire District #4 - Bacteriological Monitoring.20
Grand Isle West Shore - Bacteriological Monitoring. . . .20
Coliform Contamination - Analysis 24
Standard Plate Count - Analysis 25
Ultraviolet Radiation Disinfection - Equipment
Performance. 26
Ozone Disinfection - Equipment Performance 27
Chlorine Disinfection - Equipment Performance 28
Costs 30
Chloroform Content Analysis • • 32
6. Discussion 33
Protection of Finished Water in the Distribution System .33
UV Disinfection • 34
Ozone Disinfection 35
Chlorine Disinfection 36
References 37
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FIGURES
Number Page
1 Monthly Standard Plate Count Average — South Hero Fire
District #1 12
2 Monthly Standard Plate Count Average — Grand Isle Water
Supply Company 16
3 Monthly Standard Plate Count Average - South Hero Fire
District #2 North Shore 19
4 Monthly Standard Plate Count Average - Grand Isle Fire
District #4 21
5 Monthly Standard Plate Count Average — Grand Isle West Shore .23
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TABLES
Number Page
1 Bacteriological Data-South Hero Fire District #1 11
2 Standard Plate Count-South Hero Fire District #1
6/2/77 & 6/6/77 14
3 Standard Plate Count-South Hero Fire District #1
6/14/77 & 6/27/77 14
4 Bacteriological Data Grand Isle Water Supply Company-Ozone. . .15
5 Bacteriological Data Grand Isle Water Supply Company-Chlorine .15
6 Coliform Data-Grand Isle Water Supply Company 5/23/77 to
8/23/77 15 & 17
7 Bacteriological Data - South Hero Fire District #2
North Shore .17
8 Coliform Data-South Hero Fire District #2 North Shore 18
9 Coliform Data-South Hero Fire District #2 North Shore 5/3/76
& 7/27/76 18
10 Bacteriological Data - Grand Isle Fire District #4 20
11 Coliform Contamination - Grand Isle Fire District #4 20
12 Bacteriological Data - Grand Isle West Shore 1/76 to 1/77 . . .22
13 Bacteriological Data - Grand Isle West Shore 2/77 to 9/77 ... 22
14 Bacteriological Data - Grand Isle West Shore 6/21/77 24
15 Chloroform Content of Water 32
vii
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SECTION 1
INTRODUCTION
Chlorination has traditionally been used in the United States for dis-
infection because it is a well understood process, relatively simple,
inexpensive, and provides a measurable residual resulting in a final barrier
of protection to the water before it reaches the consumer. It has been
the experience of the Vermont State Department of Health, Division of
Environmental Health, that some small community water systems have diffi-
culties in maintaining proper chlorination practice. Chlorination practice
often results in inadequate disinfection in those small water systems where
the operators are inadequately trained. The logistics involved in obtaining
chlorine and the expertise required to properly add it are lacking in many
of these systems.
Adequacy of disinfection is of concern because there are many water
systems in Vermont using surface water without complete treatment. Of the
approximately 420 water systems in Vermont nearly 30 percent use unfiltered
surface water and 41 percent use springs as sources of supply. In many
instances, due to the geology of the State, springs yield water contained
within the upper few feet of the ground and are generally considered surface
sources. These are mainly small systems which have limited economic,
operational, and maintenance resources.
Claims had been made by various equipment manufacturers and suppliers
that ozone or ultraviolet (UV) radiation would provide better disinfection
capabilities than chlorination on small water systems. Ozone and UV radia-
tion are produced on site, using only electrical power and thus the
logistical problems of chemical supply are eliminated. Reportedly, taste
and odor problems are nonexistent. When using ozone or UV, claims had also
been made that ozone and UV radiation provided adequate disinfection without
operation and maintenance problems.
There are several reports concerning the use of ozone disinfection on
large water systems^'^ and, based on a study by Huff et al, UV radiation
had been approved for water disinfection on U.S. ships. Unfortunately,
there is a lack of information on the actual operating experience of small
water systems using ozone or UV radiation for disinfection. To determine
information on the adequacy of ozone or UV radiation for disinfection in
small water systems we obtained a demonstration contract from the U.S.
Environmental Protection Agency (EPA 68-03-2182). Commercial ozone and
UV radiation disinfection units normally designed for installation in bottled
water.plants were installed in existing water systems and monitored. An
existing chlorination unit in a water system was also monitored. Information
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was gathered on operation and maintenance requirements, performance
reliability, capital and operating costs, and disinfection performance for
the period from December, 1975, to September, 1977. We report on our
findings in this paper.
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SECTION 2
CONCLUSIONS AND RECOMMENDATIONS
(1) Neither ozone nor UV disinfection offer an advantage over chlori-
nation for small water systems. From an operation and maintenance stand-
point, ozone and ultraviolet disinfection at the present state of the art are
inferior to chlorine disinfection when used in this application. In this
respect, we see no advantage to be gained in their use. More importantly,
neither ozone nor UV disinfection provide a residual disinfectant to protect
the water in the distribution system.
(2) The main problem with chlorination on small community water systems
is inadequate operation and maintenance. Inadequate operation and maintenance
is a general problem and it results in impairments to all aspects of small
community water systems, not just chlorination. Further research is required
to determine methods of greatly improving operation and maintenance of small
water systems.
(3) UV disinfection directly at the point of use, the tap, appears to
be theoretically possible and a need for this type of application exists. How-
ever, our findings have shown that further development is required even for
this type of application. The effects of photoreactivation and dark field
repair on drinking water disinfection need to be determined. Reliable UV
intensity meters are required. Most importantly, detailed performance
standards for UV disinfection must be developed.
(4) There is a possible research need for field evaluations of UV disin-
fection equipment of superior design that corrects for the equipment defi-
ciencies cited in this study. Such field evaluations should be performed at
locations with known coliform contamination problems.
(5) Although coliform contamination should exist in any future studies
of this nature, the Standard Plate Count should be relied on as the primary
means of measuring disinfection performance because of the certainty of the
existence and density of these organisms in sufficient magnitude to measure
disinfection effectiveness and distribution system water quality. Coliform
examinations are also necessary because of their sanitary significance and
their role in the Federal Primary Drinking Water Regulations. The uncertainty
of regular coliform.,occurrence, however, restricts the use of this indicator
organism as the primary measure of disinfection performance.
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SECTION 3
BACKGROUND INFORMATION
UV RADIATION DISINFECTION
History
The germicidal effects of UV radiation have been known for many years
and are well documented. In 1878, the first recorded discovery of the
bacteriological effects of radiant energy was made, based on observations of
the effect of sunlight on a mixture of microorganisms. It was concluded
that radiation of short wavelength was responsible for their destruction.
In the early 1900's the quartz mercury vapor arc lamp was developed.
The first recorded attempt to utilize ultraviolet radiation (UV) for disin-
fection of water was in Marseilles, France, in 1910 where an experimental
apparatus was used to treat 36 m^/h (160 gpm). Jepson^ has reported that
between 1916 and 1928, UV disinfection was applied by at least four water
authorities in the United States. The largest works reportedly supplied a
population of some 12,000 and had a capacity of 96-135 1/s (1,522-2140 gpm).
However, the initial interest in UV radiation for the disinfection of
drinking water waned considerably because of the difficulties experienced
with reliability and maintenance of UV equipment and the relatively high
costs of the process.
While UV installations for use on ships has been employed since 1916,
reports of problems with this type of application continue even to the
present.6,7,8
Principles of UV Disinfection
The principles of UV disinfection are well known, albeit not completely
understood. While UV radiation extends from 15 to 400 nanometers (nm), it
is in the range between 200 nm and 310 nm where UV has the most lethal
effects on microorganisms. For most species the bactericidal effect as a
function of wavelength is greatest at about 250 to 260 nm.9
The germicidal effect of UV radiation is thought to be associated with
its absorption by various organic molecular components essential to the cell' s
functioning. The exact mechanism of destruction is still not completely
understood but it points to the absorption of UV by a nucleic acid as the
start of a photobiochemical reaction (or reactions) ultimately leading to
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the inactivation of the cell. Energy dissipation of excitation causing
disruption of unsaturated bonds appears to produce a progressive lethal
biochemical change. It appears that most of the photochemical damage
caused by UV occurs as a result of lesions such as chain breakage produced
in deoxyribonucleic acid. '
Several studies have demonstrated that microorganisms treated with UV
radiation disinfection may be subsequently reactivated. Photoreactivation
after UV treatment was discovered by Kelner in 1948.10'H Research
progressed rapidly so that a considerable body of knowledge was available
for review by 1955.12 In 1975, Carson and Peterson reported on photo-
reactivation of Pseudomonas cepacia after UV exposure and concluded that
this organism could be a potential source of contamination in UV treated
waters.^ -* Both photoreactivation and dark repair mechanisms have been
described in a variety of microorganisms. ' Conclusions concerning the
impact of photoreactivation and dark repair mechanisms on the effectiveness
of UV disinfection of drinking water have not yet been reached.
Characteristics of UV Lamps
For practical disinfection application, UV radiation is produced from
specially constructed low pressure mercury vapor lamps which emit a con-
siderable portion of their energy at the germicidal 253.7 nm wavelength. The
lamps, constructed with 10-20 mm diameter clear fused quartz envelopes, have
mercury vapor pressures of the order of 10" to 10 mm Hg, and can produce
some 85-90% of the UV output at 253.7 nm. The lamp output intensities
decrease with age usually due to internal darkening of the quartz envelope.
They have, however, a relatively long effective life (7500 hrs.). A com-
paratively high starting voltage is required but full UV output is available
after a brief 2-5 minute warmup period and the discharge can be stopped or
started at will.
The lamp, being the UV source, is a most essential part of the disin-
fection equipment and must provide the required intensity of radiation
within the equipment. The temperature of the lamp is an important factor
because decreased lamp temperature results in decreased UV output. For this
reason, the lamp is normally located in a protective quartz tube 50 mm in
diameter which runs the length of the disinfection chamber and through the
use of seals extends through and beyond the ends of the chamber. The pro-
tective quartz tube eliminates direct lamp/water contact. This results in
the lamp being kept dry, fully accessible, and maintained at an operating
temperature of 40 C.
Characteristics of UV Disinfection Equipment
The disinfection chambers, which are generally horizontal cylinders,
are usually constructed of stainless steel, although plastic chambers are
also used. The inside of the disinfection chamber is maintained at the
water system pressure, reportedly up to a maximum of 150 psi.
The disinfection chamber may be equipped with a monitoring port which
allows for viewing the inside of the chamber through a quartz window. The
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monitoring port, in turn, may be equipped with a photo-electric cell to
measure UV intensity.
Some disinfection chambers have facilities for the hydromechanical or
chemical cleaning of the inside of the chambers.
Control equipment is required to maintain and monitor the voltage
applied to the lamp(s). The control equipment may also incorporate a UV
intensity meter if the disinfection chamber is equipped with a monitoring
port and photoelectric cell. The control equipment may be mounted directly
on the outside of the disinfection chamber or at some distance from the
chamber.
Factors Affecting Germicidal Efficiency
The factors affecting UV germicidal efficiency may be grouped as
those affecting the available UV intensity or those affecting the utiliza-
tion of the available intensity. Age of lamp and coating on the outside of
the protective quartz tube are those items which may affect the available
UV intensity. The nature of the water is the primary factor affecting
utilization of UV intensity.
Huff et al found that water with color at a maximum level of 5 units,
or iron content up to 3.7 mg/1 as interfering factors in UV transmission
did not decrease efficiency of treatment. Turbidity levels up to 5 units,
they found, did not decrease treatment efficiency below acceptable limits.
However, they concluded that, generally, units of color and units of
turbidity are not adequate measures of the decrease that may occur in UV
energy transmission. The organic nature of materials present in water can
give rise to significant transmission difficulties.
OZONE
History
Ozone was first noted by Van Marum in 1785. Ozone's first important
commercial use was in the disinfection of drinking water. As early as 1892,
several experimental plants were in use; however, the first major plant placed
into operation was in Nice, France, in 1906. Ozone underwent its peak devel-
opment for water disinfection in Europe soon after its commercial intro-
duction. By 1936, some 100 municipal installations were reported to be in
operation in France with 30 to 40 more installations in other countries.-*-
It was estimated that in 1972 more than 1,000 water treatment plants were
using ozone.
Very little use has been made of ozone as a water disinfectant in the
United States. In 1940, Whiting, Indiana, began using ozone and has the
longest operating experience with ozone of any U.S. city. Whiting, however,
does not use the ozone for disinfection, but as an oxidant for taste and
odor control.
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Disinfection Efficiency
Ozone is a very powerful disinfectant. Numerous studies have shown
that relatively low concentrations of ozone (less than 0.5 mg/1) will des
microorganisms including viruses in water. ' ' ' Ozone concentratio:
of from 0.2 to 4.0 mg/1 are usually used in water disinfection.
Ozone is a powerful oxidizing gas. Ozone's great ability to oxidize
accounts for its ability to disinfect water. The mechanism of disinfection
with ozone is the result of the decomposition of ozone to oxygen (O~) and
nascent oxygen (6). The strong oxidizing potential is in the nascent oxygen
atom.
Chemical/Physical Properties
Ozone, O3, with a molecular weight of 48 has a characteristic pungent
odor. Ozone is generally encountered in a dilute form in a mixture with air
or oxygen. While ozone is more soluble in water than is oxygen, it is
difficult to obtain more than a few milligrams per liter concentration under
normal conditions of temperature and pressure because of a much lower
available partial pressure.
Under normal temperature and pressure, ozone is naturally unstable
and decomposes to oxygen. Heat accelerates this decomposition, and moisture
and several chemicals catalyze this decomposition. Ozone may also be decom-
posed photochemically. From a practical standpoint, decomposition is slow
enough to permit the use of ozone for water disinfection.
Production of Ozone
Due to its unstable nature, ozone must be produced on site. The pro-
duction of ozone may be from air or oxygen. An ozone generation system
consists of the following:
—An intake air filter and compressor, which maintains a
positive pressure through the ozone generating system,
are required for air feed units;
—A compressed air stream cooling system consisting of
either a refrigeration unit or a water cooled heat
exchange is required for air feed units;
—An air drying unit consisting of either silica gel or
calcium chloride desiccators is required for air feed
units;
—An ozone generator;
—An ozone/water mixer and contact chamber.
The compressed air stream must be cooled and dried because the vapor content
of the air should not exceed 1.38 mg/1 for maximum ozone production
efficiency.
The most common type of ozone generation consists of passing dry air
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or oxygen through a high tension electric discharge, referred to as a
"corona glow", during which some of the oxygen present is converted into
ozone. The electric discharge may take place across either plate or tubular
units. A dielectric insulating material, usually glass, is used between the
positive and negative electrodes. The voltage necessary for the high
tension electric discharge ranges from approximately 5,000 to 25,000 volts.
The high tension voltage discharge is accomplished by use of a transformer
which receives feed voltage of 110 volts for small generating systems and
up to 220 to 440 volts for larger units. Alternating current frequencies in
the generator range from 1000 Hz to 2000 Hz, with the newer ozone generators
operating at higher frequencies with reportedly increased efficiency.
The high tension electric discharge results in significant heat pro-
duction and the generator must be cooled. The smaller ozone generators
usually use air cooling. Larger ozone generators are water cooled.
Approximately 1%, weight concentration, of the air stream is converted
to ozone requiring a total of 10 to 13 kilowatt hours to produce one pound
of ozone. If oxygen feed is used, the power consumption is usually less than
for air feed and approximately 2% weight concentration is converted to ozone.
These power savings are however negated by the high cost of oxygen.
Dispersing and Dissolving Ozone in Water
Efficient use of ozone in water disinfection is dependent upon two
main factors: 1) the mass transfer of ozone from the gaseous to the liquid
phase where reaction can occur; and, 2) the rate of reaction of the ozone
with the microorganisms in the solution. However, the rate of disinfection
is not necessarily limited by the action of the residual ozone concentration
alone. Disinfection can also occur at the contact of an ozone bubble with
a microorganism. A contacting system should strive to achieve both, some-
what conflicting goals: 1) promoting ozone bubble contact by appropriate
mixing conditions; and 2) avoiding gas-stripping so as to maintain sufficient
ozone residual in the water for as long a period as possible.
-in 21 99
Various mixing techniques are now in use. ' •L>^z- in the Otto partial
injection system ozonated air is pulled into a contact chamber as a result
of a pressure loss across an injector, and then mixes with water in an up-
ward verticle flow in a chamber. In the Kerag system a propeller with a
perforated base rotates at high frequency in a wet chamber and ozonated air,
which is fed through the hollow shaft of the propeller, is pulled into the
water as a result of the rotation of the impeller. In the diffuser system,
ozonated air is introduced through porous diffusers at the bottom of a deep
contact chamber and mixes with the water.
There are, of course, various modifications of these basic techniques.
In general, the type of ozone/water mixer and contact chamber must be matched
to the specific application under consideration. An individual application
may be very suitable for the use of one particular mixing device, while a
slightly different ozone requirement cannot be adequately met with the same
mixer. The goal must be high mixing efficiencies and present techniques
reportedly achieve 90% mixing efficiencies.
8
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SECTION 4
MATERIALS AND METHODS
Five existing small water systems in Grand Isle County, Vermont,
were chosen for study. Permission for the study was obtained from the man-
aging boards of each system. All of the systems studied were within a
ten (10) square mile area and used Lake Champlain as their supply source.
Two water systems, one filtered and the other unfiltered were equipped with
UV radiation disinfection units. Ozone disinfection units were installed
on two other systems, one filtered and the other unfiltered. The fifth
system was unfiltered and continued to use its existing chlorination system.
Commercially available ozone and UV radiation equipment designed for
disinfecting drinking water was obtained and installed by a local plumber
and electrician. After the ozone and UV radiation units were installed,
each system was visited once each weekday to determine operating and
maintenance requirements. Once each week a series of samples for bacter-
iological analysis was obtained from each system. Raw, finished, and three
distribution samples were obtained. The samples were analyzed physically
for temperature and turbidity, chemically for pH, and chlorine and ozone
residuals (as applicable), and bacteriologically for total coliform, fecal
coliform and standard plate count.
Temperature was measured on site using a calibrated thermometer. pH
was recorded on site with a Beckman pH meter and combination electrode. pH
was also measured colorimetrically using bromthymol blue as an indicator.
Turbidity samples were brought to the Vermont State Health Department
Laboratory and were analyzed the same day with a Hach 2100A nephelometric
turbidimeter. Total and fecal coliform samples were analyzed using the
membrane filter technique in accordance with the 13th edition of Standard
Methods. Total bacteria samples were also processed in accordance with
the 13th edition of Standard Methods, but were allowed to incubate for 48
hours instead of 24 hours. Bacteriological samples were processed within
six hours.
UV RADIATION STUDY
An Ultraviolet Purification System's Inc. EP-160 unit was installed
at Grand Isle Fire District Number 4 Water System, which provides simple
filtration using pressure sand filters and serves 300 people. This EP-160
unit was installed after the filters. This unit was obtained by the use of
competitive bidding using the U.S. Public Health Service's "Policy Statement
for the Use of Ultraviolet Disinfection Units - 1966" in our specifications.
The EP-160 unit was rated by the manufacturer as being capable of treating
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10 1/s (160 gpm).
Another UV radiation disinfection unit was installed on the South Hero
Fire District Number 2 North Water System. This system serves 40 people.
An Ultraviolet Purification Systems, Inc. EP-50 unit with a rated treatment
capacity of 3.2 1/s (50 gpm) was installed. This unit was obtained from
U.S. Environmental Protection Agency, Region I, Office of Water Supply.
Ultraviolet light intensity was determined using the firm's "Water
Quality Monitor".
OZONE DISINFECTION STUDY
Ozone disinfection units were installed on the South Hero Fire District
Number 1 Water System which provides simple filtration using pressure filters
and serves 180 people and on the Grand Isle Water Supply Company's system
which provides no treatment and serves 185 people. Each system was equipped
with a Welsbach W-15 ozone generator and a Welsbach 8C91 contactor, capable
of disinfecting 3.2 1/s (50 gpm) of water with an ozone application dose of
2.5 mg/1 with a three minute contact time. The unit on the South Hero Fire
District Number 1 Water System was installed after filtration. The ozone
disinfection units were obtained by competitive bids.
Ozone residuals were determined using N,N-diethyl-p-phenylenediamine
(DPD). On a routine basis, residuals were determined colorimetrically as
opposed to titrating the sample.
CHLORINE DISINFECTION STUDY
The existing disinfection equipment was monitored at the Grand Isle
West Shore Water System, which serves 100 people and does not filter. A
Precision Control hypochlorinator (Model #12701-11) installed in 1975 was
used to feed sodium hypochlorite solution into the water directly before
the system's 3787 1 (1000 gal) hydropneumatic tank. This arrangement
provided a minimum 15 minute contact time before distribution to the first
service.
Chlorine residuals were determined in the field by use of a Hach
CN-66 DPD chlorine comparator.
10
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SECTION 5
FINDINGS
SOUTH HERO FIRE DISTRICT #1 - BACTERIOLOGICAL MONITORING
Raw water at this water treatment plant was pumped through pressure
filters with no pretreatment. Pressure filtration alone had little effect
on standard plate count and total coliform count. Some decrease in
turbidity was noted however. Filtered water seldom had a turbidity above
1.0 NTU. The filters usually afforded a 50% decrease in turbidity.
The water from the filters was then ozonated with a contact period of
approximately three minutes. The treated water from the ozone contact
chamber generally had an ozone residual of 0.4 mg/1. This residual ozone
in the water quickly dissipated, and it was not detectable after standing
between one to two minutes.
The ozonation system was on line for the period of May, 1976, to
September, 1977. During this period, occasional malfunctions in the equip-
ment forced a reversion to chlorine disinfection. A summarization of the
data follows. (Table 1.)
TABLE 1. BACTERIOLOGICAL DATA - SOUTH HERD FIRE DISTRICT #1
SYSTEM USING OZONE DISINFECTION
COLIFORM ORGANISMS PER 100 ML.
NUMBER NUMBER
SAMPLE SAMPLES RANGE MEAN > 4
STANDARD PLATE COUNT PER 1 ML
NUMBER
SAMPLES RANGE MEAN
RAW 67
FINISHED 69
DISTRIBUTION 198
0-259 37.7 NA
0-1 0.13 0
0-45 1.2 9
SYSTEM USING CHLORINE DISINFECTION
RAW 2
FINISHED 2
DISTRIBUTION 6
9-14 11.5
0-0 0
0-0 0
NA
0
0
65
63
189
2
2
6
1-3000
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(1250)
400-
300-
o
Q.
oRaw
XFinished
Distribution
51—-*—*—*—*—*
200-
100 -
MONTH
Figure 1. Monthly Standard Plate Count Average -- South Hero Fire District #1
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Instances of coliform contamination at South Hero Fire District #1 in
finished and distribution water can be attributed to a number of factors.
Simple failure of the ozone disinfection equipment soon after start up caused
some contamination. In one case, a solenoid valve which allowed ozone to flow
into the contact chamber burned out. Without any ozone being introduced into
the water, coliform contamination in the distribution system resulted.
A basic design flaw during the first six months of operation resulted in an
uncertainty as to where distribution system contamination originated. In the
initial disinfection system configuration, ozone was introduced into the con-
tactor at the same time that the water pumps started. This resulted in an
extremely low ozone residual in the contact chamber initially. Although all
the water in the contact chamber at this point should have been disinfected, the
possibility existed that the incoming raw water could have short circuited
through the contact chamber and not have been totally disinfected.
We found no evidence to support this during the first two months of opera-
tion in that little coliform contamination was noted in the distribution system.
However, during August and September, 1976, some contamination was noted in the
distribution system. The average coliform concentration in the distribution
system during this time period was 5/100 ml. After September of 1976, coliform
contamination of the distribution system ceased, and little contamination was
noted in the distribution system until June 20, 1977- In this intervening
period, the problem with low initial ozone residuals in the contact chamber was
solved by automatically introducing ozone into the contact chamber before water
flow commenced, but this had not completely eliminated distribution system
coliform contamination.
Of 39 distribution samples taken between June 20, 1977, and September 12,
1977, thirteen (13) showed some coliform contamination. The minimum was 1/100
ml., and the maximum 25/100 ml. The mean contamination was 4/100 ml., the
median contamination was 1/100 ml. It should be noted that ten of these contam-
inated samples were taken at the same point. This sampling point included the
highest four instances of contamination. During this period, finished water
samples showed no coliform contamination. Occurrence of coliform organisms past
the point of disinfection could be the result of either the reactivation of
organisms stressed by ozone (UV light) or regrowth of organisms in pipe sedi-
ments and not held in check by a disinfectant residual or the organisms could
have been introduced through situations such as line repairs or cross connections.
Standard plate counts at this water system showed a significant seasonal
variation. Generally, raw water counts were typically low during the winter
months, and rose during months with a higher water temperature. Finished water
standard plate counts showed little variation throughout the year. Additionally,
there appeared to be no correlation between raw and finished water standard plate
counts.
Standard plate counts in the distribution system showed a marked seasonal
variation. With very low water temperatures, standard plate counts were much
the same as those encountered In finished water during this time period. As
water temperatures rose, however, standard plate counts in the distribution
system rose dramatically. This is well illustrated for the period June -
September, 1977 on Figure 1.
13
-------
During the first two weeks of June, 1977, the ozonator became inoper-
ative, and a reversion to chlorine disinfection took place. During this
period, standard plate counts were as follows. (Table 2.)
TABLE 2. STANDARD PLATE COUNT - SOUTH HERO FIRE DISTRICT #1 6/2/77 £• 6/6/77
STANDARD PLATE COUNT/1 ML.
6/2/77 6/6/77
RAW WATER SAMPLE 39 14
FINISHED WATER SAMPLE 33 25
DIST. SAMPLE #1 14 2
DIST. SAMPLE #2 15 7
DIST. SAMPLE #3 19 5
Subsequently, ozone disinfection was reintroduced, and the following
standard plate counts were obtained. (Table 3.)
TABLE 3. STANDARD PLATE COUNT-SOUTH HERO FIRE DISTRICT #1 6/14/77 & 6/27/77
STANDARD PLATE COUNT/1 ML.
6/14/77 6/27/77
RAW WATER SAMPLE 32 44
FINISHED WATER SAMPLE 8 3
DIST. SAMPLE #1 15 1700
DIST. SAMPLE #2 46 650
DIST. SAMPLE #3 39 350
Chlorine disinfection appeared to suppress standard plate counts in the
distribution system. Ozone disinfection did not.
GRAND ISLE WATER SUPPLY COMPANY - BACTERIOLOGICAL MONITORING
Water for this system was taken from the lake, ozonated, and pumped to
a 7571 litre (2000 gallon) pressure storage tank. Several problems with the
ozone system resulted in periods of intermittent chlorine disinfection
during June and July, 1977. An inability to adequately control coliform
contamination in the distribution system necessitated abandonment of the
ozone disinfection system in July, 1977.
The ozone disinfection unit operated for the period of September, 1976,
to July, 1977. A summary of the data follows. (Table 4.)
14
-------
TABLE 4. BACTERIOLOGICAL DATA GRAND ISLE WATER SUPPLY COMPANY - OZONE
COLIFORM ORGANISMS/100 ML.
NUMBER NUMBER
> 4
STANDARD PLATE COUNT/1 ML.
NUMBER
SAMPLES RANGE MEAN
RAW
FINISHED
DISTRIBUTION
34
32
102
0-350
0-4
0-13
46.7
0.5
1.4
NA
2
8
30
31
93
<1-451 93.3
<1-145 20.4
1-1700 163
During this period, the chlorinator operated at times when the ozone
system was not functioning. A summary of data while the system used
chlorination is as follows. (Table 5.)
TABLE 5. BACTERIOLOGICAL DATA GRAND ISLE WATER SUPPLY COMPANY-CHLORINE
COLIFORM ORGANISMS/100 ML. STANDARD PLATE COUNT/1 ML.
NUMBER NUMBER NUMBER
SAMPLES RANGE MEAN > 4 SAMPLES RANGE MEAN
RAW
FINISHED
DISTRIBUTION
10
10
30
0-48
0-0
0-2
17.4
0
0.2
NA
0
0
10
10
30
5-107
-------
(582)
400
- 300
o
0.
200
100
oRaw
X Finished
Distribution
System used
chlorine for
disinfection
f //
-------
TABLE 6.
COLIFORM ORGANISMS/100 ML.
7/12/77 7/14/77 7/27/77 8/2/77
DISINFECTION
METHOt
RAW
3:
FINISHED
DIST.
DIST.
DIST.
#1
#2
#3
OZONE
19
0
1
1
6
CHLORINE
0
0
0
0
0
OZONE
1
0
0
5
6
CHLORINE
0
0
0
0
0
This data clearly shows that coliform contamination could not be con-
trolled after the point of disinfection with ozone as the disinfectant.
Standard plate counts at this water system showed a similar pattern to
those at South Hero Fire District #1. With increasing water temperatures,
standard plate counts in the distribution system showed a marked increase.
Using chlorine disinfection, no such increase was noted.
After July 27, 1977, all attempts at ozone disinfection were abandoned
and chlorine was used exclusively for disinfection.
SOUTH HERO FIRE DISTRICT #2 (NORTH SHORE SYSTEM) - BACTERIOLOGICAL MONITORING
The North Shore System pumped water from the lake through a pressurized
UV radiation unit to disinfect the water, into a 3785 litre (1,000 gallon)
hydropneumatic tank and then to the distribution system. The distribution
system consisted of a single 5.1 cm. (2") galvanized iron pipe approximately
0.8 km (0.5 mile) in length, serving ten houses.
The hydropneumatic tank was often waterlogged, because air recharge was
done infrequently. This caused short cycling of the pump. Only about 7570
litres (2,000 gallons) were pumped per day.
The ultraviolet disinfection system was on line for the period of
December, 1975, to September, 1977, except during August and September, 1976,
when because of renovations to the system the South Shore System supplied
chlorinated water to the North Shore system. A summary of the data for the
periods when UV radiation was used follows. (Table 7.)
TABLE 7. BACTERIOLOGICAL DATA-SOUTH HERD FIRE DISTRICT #2 NORTH SHORE
COLIFORM ORGANISMS/100 ML.
RAW
FINISHED
DISTRIBUTION
NUMBER
SAMPLES
79
80
240
RANGE
0-302
0-3
0-14
MEAN
25.2
0.1
0.2
NUMBER
> 4
NA
0
3
NUMBER
SAMPLES
78
80
234
RANGE
6-418
1-400
MEAN
72.4
14.9
29.2
17
-------
Monthly averages of standard plate counts are shown in Figure 3.
At South Hero Fire District #2, North Shore System, there were several
instances of coliform contamination between mid-July and late August, 1977.
In all cases the unit's ultraviolet light intensity sensor indicated that
the disinfection dosage was in the "safe" range. Below is a summary of
data for this time period. (Table 8)
TABLE 8. CDLIFORM DATA-SOUTH HERO FIRE DISTRICT #2 NORTH SHORE
COLIFORM/100 ML.
RAW
FINISHED
DIST.
DIST.
DIST.
#1
#2
#3
7/18
0
0
3
0
0
7/25
1
1
2
1
3
8/1
6
3
2
0
0
8/9
2
0
0
0
1
8/15
49
0
0
0
0
8/22
9
0
0
0
0
8/29
100+
0
9
1
14
9/
25
0
0
0
0
6.
The data indicates that in certain instances, coliform contamination was
noted immediately after disinfection (7/25/77 and 8/1/77). Also, there were
instances when contamination was noted in the distribution system although
none was noted immediately after disinfection. Most notably, this occurred
on August 29, 1977. It was difficult to ascertain whether breakthrough was
occurring at the point of disinfection, or past the point of disinfection,
or both.
Additionally two instances of coliform contamination were noted in 1976.
Table 9)
TABLE 9. COLIFORM DATA-SOUTH HERO FIRE DISTRICT #2 NORTH SHORE 5/3/76 &7/27/76
COLIFORM/100
RAW
FINISHED
DIST.
DIST.
DIST.
#1
#2
#3
5/3/76
11
0
5
2
0
ML.
7/27/76
10
0
0
3
2
In both cases, the ultraviolet equipment appeared to be operating
properly.
No significant trends were noted in standard plate counts in the distri-
bution system. The highest counts were noted in October, 1976. This was
just after the ultraviolet disinfection was reinstituted, and after some work
had been done on the distribution network. There was a general rise in
standard plate counts during the summer of 1977.
18
-------
400-
- 300
O
a.
200
100
oRaw
xFinished
Distribution
*
* *
'Water System
Inoperative
*
MONTH
Figure 3. Monthly Standard Plate Count Average -- South Hero Fire District #2
North Shore.
-------
GRAND ISLE FIRE DISTRICT #4 - BACTERIOLOGICAL MONITORING
This water system provided simple filtration and ultraviolet radiation
disinfection. This disinfection system operated for the period of April 5,
1976, to July 16, 1976. After July 16, 1976, ultraviolet disinfection was
discontinued because of equipment failure.
A summary of the data is as follows. (Table 10)
TABLE 10. BACTERIOLOGICAL DATA - GRAND ISLE FIRE DISTRICT #4
COLIFORM ORGANISMS/100 ML. STANDARD PLATE COUNT/1 ML.
NUMBER NUMBER NUMBER
SAMPLES MEAN RANGE > 4 SAMPLES MEAN RANGE
RAW
FINISHED
DISTRIBUTION
14
14
42
34
3.
3.
5
5
2-100
0-33
0-100
NA
3
3
13
13
39
50
26
23
< 1-280
< 1-140
3-110
Monthly averages of standard plate counts are shown in Figure 4.
Despite this short operating period, coliform contamination in the dis-
tribution system was noted on several occasions. Significant contamination
is noted on the following table. (Table 11)
TABLE 11. COLIFORM CONTAMINATION-GRAND ISLE FIRE DISTRICT #4
COLIFORM ORGANISMS/100 ML.
DATE; 5/25/76 6/1/77 6/28/77 7/6/77
RAW 36 100+ 87 5
FINISHED 8* 33* 8* 0
DIST. #13 28 3 0
DIST. #2 0 100+ 0 0
DIST. #30 803
* SAMPLE TAKEN AFTER HYDROPNEUMATIC STORAGE TANK
All follow up samples taken showed no contamination. Additionally,
followup samples taken directly after the ultraviolet unit showed no con-
tamination.
No trends were noted in standard plate count results.
GRAND ISLE WEST SHORE-BACTERIOLOGICAL MONITORING
This water system used sodium hypochlorite for disinfection, with no
filtration. After chlorination, water was delivered to a 3,785 litre (1,000
gallon) hydropneumatic tank. For the period January, 1976, to January, 1977,
the local operator serviced the chlorinator. Results for this time period
are as follows. (Table 12)
20
-------
400
_ 300
E
o
o.
200
100U
oRaw
xFinished
* Distribution
*
<6
MONTH
Figure 4. Monthly Standard Plate Count Average - Grand Isle Fire Distri
istrict #4.
-------
TABLE 12. BACTERIOLOGICAL DATA-GRAND ISLE WEST SHORE 1/76 TO 1/77
JANUARY 1976 - JANUARY 1977
OPERATOR MAINTAINED
COLIFORM ORGANISMS/100 ML.
NUMBER NUMBER
SAMPLES MEAN RANGE > 4
STANDARD PLATE COUNT/1 ML.
NUMBER
SAMPLES MEAN RANGE
RAW
FINISHED
DISTRIBUTION
47
46
138
66.
5.
2.
3
7
1
1-311
0-100
0-97
NA
4
10
45
44
135
128.
52.
104.
5
8
8
9-850
M-330
M-850
Coliform contamination occurred frequently at this water system for the
period January, 1976, to January, 1977. The main cause of this was inadequate
chlorination practice. On five separate occasions, no chlorine was present
in the distribution system or finished water. This was caused by an unfilled
chlorine solution feed tank. Subtracting these results from the mean coli-
form density for the period, a mean concentration of .06 coliform/100 ml.
in the distribution system results.
Additionally, finished water was collected at a point which generally
afforded short chlorine contact time. This would account for occasional
coliform contamination in the finished water even when chlorine was present.
For the period February, 1977, to September, 1977,- we controlled the
chlorination practice and attempted to maintain a free chlorine residual
throughout the distribution system. Results for this time period are as
follows. (Table 13)
TABLE 13 - BACTERIOLOGICAL DATA - GRAND ISLE WEST SHORE 2/77 TO 9/77
FEBRUARY 1977 - SEPTEMBER 1977
PROJECT MAINTAINED
COLIFORM ORGANISMS/100 ML.
NUMBER NUMBER
SAMPLES MEAN RANGE >4
STANDARD PLATE COUNT/1ML.
NUMBER
SAMPLES MEAN RANGE
RAW
FINISHED
DISTRIBUTION
31
31
93
34.
4.
1.
0
1
1
0-204
0-128
0-73
NA
1
4
31
31
31
117.
53.
27.
5
1
4
6-650
1-390
-------
..(593)
1\J
U>
400 -
oRaw
XFinished
Distribution
Chlorination by Operator
Chlorination by State
Health Department
MONTH
Figure 5. Monthly Standard Plate Count Average -- Grand Isle West Shore.
-------
sample results were obtained. (Table 14)
TABLE 14 - BACTERIOLOGICAL DATA-GRAND ISLE WEST SHORE 6/21/77
CL2 RESIDUAL CDLIFDRM/100 ML. SPC/1 NIL.
RAW
FINISHED
DIST. #1
DIST. #2
DIST. #3
1.2
0.8
0.4
0.3
FREE
FREE
FREE
FREE
34
1
14
7
73
14
16
13
10
9
Follow up samples the next day showed no contamination in either the
finished water or in the distribution system. The standard plate count was
not unusually high.
During the period, no other major contamination was noted. If this set
of results were dropped from the data, a mean coliform density in the distri-
bution system would have been 0.1/100 ml., with one sample having a coliform
density greater than 4/100 ml.
Standard plate counts at this water system showed a definite corelation
to chlorine residual. For example, in January, 1977,- the chlorinator became
inoperative and this resulted in a dramatic increase in the standard plate
count one week (1-12-77). Standard plate counts were as follows: Raw, 13/
1 ml, finished, 330/1 ml., and distribution average 205/1 ml.
The previous week (1/5/77), when the chlorinator was working properly,
counts were: raw, 40/1 ml., finished 26/1 ml., and distribution average
14/1 ml. This example was true in most instances when low or no chlorine
residuals were present in the distribution system.
Finished water bacteriological counts were often only slightly below the
raw water bacteriological counts. This is explained by the fact that
finished water was sampled directly from the unbaffled hydropneumatic tank
immediately after chlorination. Very short contact times occurred here.
Thus, the chlorine, which needs between 20 minutes and 3 hours for adequate
disinfection did not have sufficient contact time.
When an adequate chlorine residual was detected in the distribution
system, standard plate counts were generally low. A study conducted at the
onset of the project before any alternate disinfection equipment had been
installed generally showed a logrithmatically inverse relationship between
standard plate count and chlorine residual in the systems under observation.
COLIFORM CONTAMINATION-ANALYSIS
Absence of coliform organisms in the distribution system using ozone or
ultraviolet radiation disinfection could not always be assured, even when
these systems appeared to be operating properly. This was especially true
during the summer months. At the Grand Isle Water Supply Company, ozonation
24
-------
was discontinued after July, 1977, because contamination could not be
eliminated from the distribution system. This occurred despite the fact
that the disinfection system appeared to be operating properly and that
finished water samples had no coliform contamination.
At South Hero Fire District #2, coliform organisms were seldom noticed
in the distribution system. However, in the summer of 1977, coliform con-
tamination occurred several times, despite the fact that the ultraviolet
intensity monitoring device supplied with the unit showed an adequate ultra-
violet dosage. This observation can be interpreted that either the intensity
monitoring device did not measure the intensity precisely or that UV did not
provide satisfactory disinfection.
These instances of contamination emphasize the fact that when there is
no residual disinfectant, the only sure way to ascertain that no problems
exist in the distribution system is with bacteriological testing. Except
for the one instance at Grand Isle West Shore system, when coliform contami-
nation was found despite an adequate chlorine residual, a free residual
chlorine provided a ready indicator of no coliform contamination.
We found that proper operation and maintenance of the disinfection
system is the most important aspect in assuring proper disinfection, regard-
less of what kind of disinfectant is used. This was clearly indicated while
monitoring the chlorinated Grand Isle West Shore System for the period
January, 1976, to January, 1977. As will be discussed, similar problems
would probably occur with ozone and ultraviolet disinfection systems.
STANDARD PLATE COUNT-ANALYSIS
From the data, it is evident that there was a significant rise in the
standard plate count in the ozonated systems in the distribution system
samples. This was not the case when the systems were properly chlorinated.
Several factors could have caused this.
Regrowth of Bacteria Past the Point of Disinfection
With rising temperatures beginning in late May, accelerated regrowth of
bacteria may have occurred. There would be no disinfecting residual to
counteract this. Additionally, recent studies have shown that organics in
water which have been ozonated actually provide more usable "nutrients" to
bacteria than the unozonated organics and thus encourage regrowth.
Inadequately Disinfected Repairs to the Distribution System
During the months of April and May, 1977, several repairs to the distri-
bution systems of Grand Isle Water Supply Company and South Hero Fire Dis-
trict #1 were made. Disinfection is not usually practiced in the trans-
mission line where these repairs occur. Without any disinfectant residual,
growth of any organisms introduced could not be controlled.
Low or Negative Pressure in the Transmission Lines
This is a frequent problem in these water systems. Storage of water is
accomplished by using small pressure tanks. Power outages are frequent. The
25
-------
combination of these two factors cause loss of water pressure in the lines
after only a short length of time during power failure. Additionally, there
is a further problem in that many transmission lines are inadequately sized
and old.
Backsiphonage and/or entrance of contamination through leaks could occur
at many points in the system. With no residual disinfectant, control of
growth of any bacteriological contamination would be nonexistant.
At the South Hero Fire District #2, we did not note the levels of
regrowth that were observed at the ozonated water systems. However, it is
important to state that there was a significant difference in the distribu-
tion system. As mentioned, it is quite limited with only a 1/2 mile length
of galvanized iron pipe. There were no repairs to this pipe during the
time period in which results are displayed.
At Grand Isle Water Supply and South Hero Fire District #1, the
distribution systems are much more extensive, with several miles of various
types of pipe. Several repairs were made on these systems during the time
period. This is significant in that it points out that bacteriological
results at the five water systems cannot be compared to one another without
taking into account the differences in their distribution networks. For a
more exact comparison, all the disinfection systems would have to be used
on the same water system on a rotating basis.
ULTRAVIOLET RADIATION DISINFECTION - EQUIPMENT PERFORMANCE
In obtaining UV radiation disinfection equipment we found six firms
offering units ranging in capacity of .19 1/s (3 gpm) to 3155 1/s (50,000
gpm). Most, but not all, of the firms made claims that their equipment could
be used to disinfect potable water. Present commercial application of UV
radiation units range from the treatment of water used to manufacture drugs
and cosmetics to the disinfection of potable water on ships.
The equipment was relatively easy to install in the existing water
systems' buildings. The units were compact 91x30x30 cm (36"xl2"xl2") for
the 3.2 1/s (50 gpm) unit and 169x42x42 cm (66Vx 16V x 16V) for the 10
1/s (160 gpm) unit. A local plumber and electrician installed the units in
approximately 24 man hours per unit for a total installation cost of $400
for the 3.2 1/s (50 gpm) unit and $800 for the 10 1/s (160 gpm) unit.
The major problems noted with the units used in the study can be
grouped into the following categories.
Performance Standards
We have failed to find any nationally recognized governmental or
industry standard(s) for UV radiation units for the disinfection of community
water systems.
UV Radiation Intensity Measuring Device
26
-------
On the disinfection units studied consistent problems were noted with
the UV radiation intensity measuring device. This device consists of a UV
transparent quartz window in the side of the disinfection chamber with an
attached photoelectric cell and a meter on the control panel. The photo-
electric cell, according to the manufacturer, responds only to UV radiation
in the germicidal range of 253.7 nm.
Problems noted include failure to obtain "on-scale'1 readings, photo-
electric cells response to visible light, constant response to varying UV
and visible light, and variations in intensity readings when photoelectric
cells were interchanged.
Leakage
Water leakage problems have ranged from small leaks around the com-
pression gaskets of the quartz tube to flooding of the Grand Isle Fire Dist-
rict Number 4 Water Treatment Plant.
OZONE DISINFECTION - EQUIPMENT PERFORMANCE
In obtaining ozone disinfection equipment, generator and contactor, we
found five firms offering ozone generator units capable of producing .68
kg/d (1.5 Ibs/d) which was required for the needed water flow rates of 3.2
1/s (50 gpm). Most of the ozone generators in this range were normally used
for research purposes. Of the three firms responding to our bids for ozone
generating and contact units, only one firm had standard contactors available
as well as generators.
The equipment was difficult to install in the existing water systems'
buildings. The units were large and heavy: generator 168x91x76 cm (66"x36"x
30"), approximately 386 kg (850 Ibs.); contactor 69 cm dia-193 cm h (27" dia
x 76" h ), 68 kg (150 Ibs.). Extensive modifications were required in the
piping and electrical systems at each site. The average installation cost was
$1,600 including materials for each site. Approximately 80 man hours were
required for installation at each site.
While no national standards are available, at least there are no con-
fusing claims of standards. Based upon existing studies and consultations,
ozone disinfection equipment capable of supplying a maximum of 2.5 mg/1 ozone
with a contact time of three minutes was obtained. Generally, an ozone res-
idual of from 0.3 to 0.5 mg/1 at the outlet of the contact chamber was
obtained.
The most significant problem with ozone is operation and maintenance.
The ozone system was found to be far more complicated than either chlorine
or UV. In addition to the ozone generator and contactor with their auxil-
iary equipment, a second pump has to be used in the system, since the con^
tactor must operate at atmospheric pressure.
In less than a year of operation we had to repair much of the auxil-
iary equipment. Two flow control solenoid valve coils were replaced due to
overheating. Check valve o-rings in the driers cracked, causing drier
27
-------
failure. Shock mounts on the air compressors check valve burned out and had
to be replaced. Various ozone leaks, broken hoses, and loose or burned out
wiring had to be repaired.
At Grand Isle Water Supply Company we lost cooling water flow to the
ozone tubes when the ozone system was inadvertently shut down by the local
plant operator. The dielectric shells froze which subsequently led to the
cracking of all three dielectrics.
When using air feed to produce ozone, air compressors are necessary
and these compressors and air driers must be operated on a continual basis.
This is necessary in order to maintain a constant dry air environment in the
ozone generating tubes. We estimate that the compressors and driers would
have to be overhauled at least on a yearly basis for proper operation. The
fact that the air compressor must run continually also adds significantly to
the electrical costs. The compressor which we used drew approximately nine
amps continually.
Alternatives are available to using air feed and operating the com-
pressors on a continual basis. It would be possible to bring bottled or
liquid oxygen into the plant and thus eliminate the need for compressors
or driers. However, this brings about a new item of maintenance and cost.
Bottled or liquid oxygen is more difficult to supply and store than calcium
or sodium hypochlorite. During the winter, delivery of bottled oxygen to the
small plants would be difficult.
CHLORINE DISINFECTION - EQUIPMENT PERFORMANCE
We encountered no major problems with the chlorine disinfection equip-
ment studied. However, contamination in the system resulted when the
chlorinator's solution feed tank was allowed to be pumped dry, so that no
chlorine was injected into the water. Additionally, the chlorinator pump
lost its prime when there was no solution in the tank to be pumped. If the
chlorinator was not re-primed when the solution feed tank was refilled (after
having been pumped dry), it would not pump.
Operating failures occurred at least five times during the period when
we were monitoring the Grand Isle Water Supply Company.system. In all cases,
coliform contamination, ranging from 1/100 ml. to 97/100 ml,, was detected in
the distribution system.
Operation and Maintenance Requirements
One of the main purposes of the disinfection demonstration project was
to determine if an alternate disinfectant to chlorine could be found which
would substantially reduce operation and maintenance requirements. We have
found that neither ozone nor ultraviolet light meet this requirement.
The following is a comparison of routine maintenance for the distri-
bution systems.
28
-------
Ozone
Check ozone residual at outlet of contact chamber, adjust ozonator
as necessary.
Check air pressure and flow from compressor and after drier.
Check for proper operation of drier.
Check cooling water flow.
Check solenoid valves for proper operation.
Check for proper operation of all accessory controls, time delay
relays, and level controls.
Ultraviolet Light
Check ultraviolet monitoring device for ultraviolet intensity.
Check lamps for proper operation.
Chlorine
Check chlorine residual in distribution system.
Check solution feed tank level.
Weekly
Ozone
Check for leakage in ozone gas piping.
Clean air intake filters.
Ultraviolet
Check for leakage around quartz tubes
Calibrate ultraviolet intensity measuring device for proper
sensitivity.
Chlorine
Fill chlorine solution feed tank.
Every 2-6 months (depending on conditions)
Ozone
Clean dielectric tubes.
Check tube seals for leakage.
Check drier seals for cracks.
Check solenoid valve coils for heat damage.
Ultraviolet
Clean interior of ultraviolet chamber
Clean contacts on bulbs.
Check fail safe devices for proper operation.
Chlorine
Clean out chlorine injection line.
Yearly
Ozone
Rebuild air compressor.
Rebuild drier.
Replace rubber air compressor lines.
Ultraviolet Light
Replace bulbs.
29
-------
Examine seals, replace if necessary.
Have UV intensity meter calibrated.
Chlorine
Examine diaphragm for wear.
Clean chlorine solution feed tank.
Extraordinary maintenance must also be considered. Probability of
equipment failure becomes more common with increasing complexity of equip-
ment. With equipment failures, comes the additional problem of availability
of equipment. Disinfection systems must be reliable, and if they do break
down, replacement parts must be easily obtainable. Generally, replacement
parts for chlorinators are much more readily available than either parts for
ozonators or ultraviolet light disinfection systems.
The consideration of safety of operation must also be taken into account.
Ozone gas is toxic, and may cause respiratory difficulty with only slight
exposure. The possibility for an ozone gas leak would always be present.
Persons who were not aware of the dangers of the gas could take in harmful
quantities. This situation would be likely in a small rural water system.
Ultraviolet light can cause radiation burns which can become infected
and cause conjunctivitis with only slight exposure to the eyes. Precaution
must be taken to avoid this. The fragility of the seals and quartz tubes in
use on most ultraviolet light disinfection units may also be a problem. The
accidental rupture of a seal, or breaking of a quartz tube could cause water
to be released from the unit at high pressure. Consequences could range from
the soaking of a person present to flooding of the water treatment plant. This
could be especially hazardous during the winter months.
Chlorine when used as 12% sodium hypochlorite solution must be handled
with care, and skin contact must be avoided.
COSTS
The following are approximate capital costs encountered during the pro-
ject (labor costs not included), for a 3.2 1/s (50 gpm) system.
Initial Capital Costs
-Hypochlorination: $ 550.
-Ultraviolet light water purifier: 1,995.
-Ozonation: 13,735.
Operational costs for the above system pumping 75,758 I/day (20,000 gpd)
are as follows.
Chlorination
Assume dosage at 2 mg/1
Cost of chlorine $5.00 for 5 gallons of 12% NaOCL
Cost of Electricity - $.05/KWH
Chlorine .31 gallons/day 13% NaOCL = $.31 = $113/year
Electricity chlorinator on for 6.67 hrs./day draws 230 watts =
1.5 KWH/day = 550 KWH/year = $28
30
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TOTAL $141.00
Ultraviolet Radiation Purification
Assume unit to run continuously regardless of whether water is
flowing or not.
UV bulbs—one new set per year.
9 bulbs at $30 per bulb - $270
Electricity draws 360 watts - 8.6 KWH/day - 3154 KWH/year at $.05 -
$158
Cleaning - citric acid at $2.50/lb., 3 Ibs/cleaning 4 cleanings/year
$30
TOTAL $458.00
Ozonation
Assume Welsbach compressor runs continually to maintain dry air
environment in ozone producing tubes.
Electricity - compressor draws 1 KW - 24 KWH/day - 8760 KWH/year =$438.
Ozonator draws 150 watts at 6.67 hrs/day - 1 KWH/day - 365 KWH/year-$18
Parts for rebuilding air compressors and driers $75/year
TOTAL $531.00
Prom this evaluation it is obvious that applying ozone or ultraviolet
light disinfection in place of chlorination in an existing rural water
system using small pressure storage tanks is significantly more expensive
than disinfecting with comparable chlorination equipment.
It must be stressed that these were costs incurred by the project as
the systems were operated.
Obviously modification could be made in each system to change both
capital and operation and maintenance costs. Since the systems involved
are all automatic in operation with limited pressure storage, UV and ozone
systems had to be designed to fit the particular pumphouse. Thus, the UV
unit had to be run all of the time since water is called for frequently
and it would be impractical to turn the unit on and off and to warm it up
for three minutes each time. With design modifications in the treatment
plant, it would be possible to have the unit on only when the pumps are
running. This might save both on electricity and bulb life. The same is
true for ozone equipment.
Capital costs could be reduced in the ozone system by designing and
building a contactor. The Welsbach unit was used by us only because it fit
well into the existing pumphouse. Additionally, if an inexpensive source
of oxygen were obtained, the ozone generator size could be reduced. Savings
on air compressors and driers could also be realized.
It must be mentioned that it is also possible to reduce chlorination
costs, most likely by finding a more inexpensive source of chlorine such as
31
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gas chlorination.
CHLOROFORM CONTENT ANALYSIS
During 1977, four series of samples from each water system were sub-
mitted to the Lawrence Experiment Station in Lawrence, Massachusetts for
chloroform analysis. Results are as follows. (Table 15)
TABLE 15. CHLOROFORM CONTENT OF WATER
SAMPLE LOCATION
SOUTH HERO F.D.tfl
SOUTH HERO F.D.#2
GRAND ISLE WATER
SUPPLY
GRAND ISLE WEST
SHORE
RAW
FINISHED
DIST.
RAW
FINISHED
DIST.
RAW
FINISHED
DIST.
RAW
FINISHED
DIST.
MICROGRAMS/LITRE CHC13 FOUND
1/31/77 3/9/77 6/8/77 6/29/77
0.1 0.6
ND
1.3
1.2
0.4
3.3
1.2
1.5
1.7
0.7 1.8
29.5 20.8
ND
5.9
23.0
ND
ND
ND
ND
ND
ND
ND
1.5
27.0
ND
ND
ND
ND
ND
ND
ND
15.8
40.1
15.2
27.8
56.4
8/4/77
ND
ND
ND
ND
ND
ND
ND
0.1
>0. 1
ND
30.3
71.0
As expected, only chlorinated systems showed significant chloroform
formation. In all cases, Grand Isle West Shore was chlorinated. On June 8,
1977, South Hero Fire District #1 was chlorinated and on June 29, 1977,
Grand Isle Water Supply Company was chlorinated.
32
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SECTION 6
DISCUSSION
PROTECTION OF FINISHED WATER IN THE DISTRIBUTION SYSTEM
The process of disinfection, if it is to adequately protect the con-
sumer's drinking water, must extend beyond the treatment plant into and
throughout the distribution system. A disinfectant residual is required in
the distribution system to protect the bacteriological quality of the drink-
ing water. For this reason chlorine has been extensively used in the United
States because, when properly applied, it provides effective initial disin-
fection and residual disinfection in the distribution system.
The relationship between chlorine residual and protection of the
bacteriological quality in the distribution system is well documented. In a
study by Buelow and Walton it was found that the probability of finding
coliform bacteria in a distribution system sample decreases as the residual
chlorine concentration of the water increases. Baylis found that main-
tenance of residual chlorine in the water throughout the system is generally
the only safeguard that may be used under existing conditions in many cities.
A substantial free chlorine residual may correct damage created by undetected
cross connections, except in instances of major contamination. Even in those
instances of major contamination the loss of residual chlorine in a localized
area can serve as an indicator that foreign material has entered the system
and as a monitor to detect contamination.
Regardless of the degree of effectiveness of initial disinfection,
neither ozone nor UV provide any appreciable residual disinfectant to protect
the distribution system. A residual disinfectant, such as chlorine, is re-
quired after either ozone or UV disinfection to protect the distribution
systems. The need to maintain a residual disinfectant in the distribution
systems after ozonation has been recognized on large systems in France.
It is impractical to use ozone or UV for initial disinfection and then
add chlorine to maintain a residual in the distribution system in small commu-
nity systems. On most community water systems, especially the small systems
that we studied, we have found that chlorination alone, when properly practiced,
provided initial disinfection equal to or better than ozone or UV and in addition
provided a residual to protect the distribution system. Proper chlorination was
less costly both in terms of initial and operating costs and presented few
operation or maintenance difficulties.
The use of ozone or UV without a supplemental chlorine residual would
necessitate extreme care in construction of the distribution system and connected
33
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plumbing. It would have to be absolutely free of cross connections and
low water pressure situations. Increased maintenance of the distribution
lines by use of regular flushing, frequent enough to eliminate deposits
that could harbor bacterial growth, would also be necessary.
UV DISINFECTION
On a theoretical basis, UV radiation should be a satisfactory method
of initial disinfection. The potential problems resulting from subsequent
contamination by photo reactivation and/or dark field repair have not been
researched and assessed for the disinfection of drinking water. Even if it
is found that photoreactivation and/or dark field repair present no problems,
we have determined that UV disinfection is not adequate for small community
water systems because of the lack of a residual disinfectant and the result-
ing hazard of contamination in the distribution system. However, adequate
UV disinfection of water of suitable quality at the point of use appears to
be theoretically possible. UV disinfection of drinking water at the consum-
er's tap would eliminate the known hazards of distribution system contamination.
Even this limited role of UV disinfection of drinking water at the tap
would not be possible until several problems noted with the UV disinfection
units are corrected. These problems are with performance standards, UV
radiation intensity measuring devices, leakage, and bacteriological contam-
ination breakthrough.
Performance Standards
At present, there are no reliable performance standards for UV disin-
fection units for drinking water. There is a Department of Health, Educa-
tion and Welfare (DREW) "Policy Statement on Use of the Ultraviolet Process
for Disinfection of Water" that is ambiguous and inadequate for multi-tube
units. It cannot be considered to be a performance standard.
During the course of obtaining a UV radiation unit for the study, we were
referred to a "new standard." We found that this "new standard" was an
excerpt from the potable water maintenance section of the DHEW "Recommenda-
tions of Vessel Sanitation" issued in 1974. This "new standard" is not a
performance standard and contains unknown disinfection parameters. We have
been unable to obtain technical justification for these "new standards" or an
explanation of the disinfection parameters used. Even within the UV disin-
fection equipment supply industry there is sentiment that the "new standard"
is, from a scientific point of view, completely without basis.
No known reliable performance standards for UV disinfection units exist
today. Until standards are developed concerning reliability of performance
in addition to biological effectiveness, and UV disinfection units meeting
the performance standards are available, reliance cannot be placed on this
method of disinfection.
UV Radiation Intensity Measuring Devices
In addition to our findings, a study conducted by the DHEW, Center for
Disease Control, during November and December, 1976, of UV disinfection
equipment in actual use on seven passenger cruise vessels found similar
34
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problems with UV radiation intensity measuring devices. These findings point
out another reason why UV disinfection of drinking water is not acceptable at
this time.
With UV disinfection there is no residual either in the contact chamber,
immediately after the contact chamber, or in the distribution system. There-
fore, the only on site method of determining adequacy of disinfection is by
measuring UV radiation intensity in the contact chamber. The UV radiation
intensity measuring devices which were supplied with the units used in our
study have not provided adequate monitoring of disinfection dosage.
From a public health standpoint, our experience with the UV radiation
intensity measuring devices used on the disinfection units used in this
project indicates UV radiation disinfection is not acceptable. The monitor-
ing of UV radiation intensity within the contact chamber is the only method
readily available for a water system operator to determine if the required
amount of UV radiation is being applied to the water to be disinfected.
Without a reliable method of determining UV penetration through the contact
chamber there is a significant health hazard.
However, there does not appear to be any scientific reason why a
reliable intensity measuring device capable of detecting UV radiation in
the germicidal range cannot be developed for widescale use. Such a device
would eliminate the problems noted.
Leakage
Leakage as experienced with the UV disinfection units studied is not
acceptable. Again, however, this appears to be a problem that should be
easily corrected.
Bacteriological Contamination
In addition to bacteriological contamination being detected in the
distribution systems studied, there were instances when contamination was
noted directly after: the disinfection chamber. Contaminated water was also
detected after a UV disinfection chamber by a DREW, Center for^Disease
Control, study of a disease outbreak aboard a passenger ship. These
findings are in conflict with laboratory studies concerning the adequacy of
UV disinfection of water. This problem should be resolved by a study of
UV disinfection of drinking water including consideration of photoreactiva-
tion and/or dark field repair and the development of reliable performance
standards.
OZONE DISINFECTION
The lack of a reliable residual disinfectant to protect the water in
the distribution system makes ozone disinfection not acceptable for a small
community water system. In addition, it has been our experience that ozone
disinfection requires far more equipment and resultant operation and main-
tenance input than either chlorination or UV disinfection. There does not
35
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appear to be a technically feasible method, at this time, of significantly
reducing the complexity of ozone disinfection.
CHLORINE DISINFECTION
Our experience indicates that when proper chlorination is practiced and
a chlorine residual is maintained in the distribution system, chlorination
provides reliable disinfection. The equipment is inexpensive, dependable,
and easy to operate. On the average, a fifteen minute per day period at the
treatment plant was all that was required for operation and maintenance of
the hypochlorination system studied.
The time necessary to service the hypochlorination equipment was little
more than that required for a daily inspection visit to the plant which is
recommended as good operation and maintenance procedure. However, we did
find that daily inspection visits on small water systems are often neglected.
It is now apparent that those problems which were felt to be associated only
with chlorine disinfection are in fact merely indicators of the much larger
problem of general poor operation and maintenance of small water systems.
Since we had, in the past, monitored mainly those parameters associated
with disinfection this had appeared to be the only problem. We have found
that along with disinfection, all other aspects such as maintenance of
pressure, monitoring, repair of distribution system anomalies, etc., often
are neglected on small water systems. When proper operation and maintenance
is practiced, chlorination presents no problems.
Q / QR Q £ Q~7
Recent studies '' ' ' have found that chlorination results in the
production of chlorinated organic compounds which have been detected in
drinking water. In a study of New Orleans drinking water,- the existence of
certain chlorinated organic compounds in the water has been associated with
elevated cancer rates. ' However, the association between chlorinated
organics in drinking water and cancer has been challenged.^ The health
hazard, if any, resulting from the presence of chlorinated organic compounds
in drinking water has not, at present, been completely determined. Further
studies are being conducted to determine the health hazard, if any, of
chlorinated organic compounds in drinking water and, if necessary, to
establish maximum safe limits of these compounds.
If it is determined that chlorinated organic compounds do present a
real health hazard and present levels of these compounds in drinking water
exceed maximum safe limits, action will be required. It is known that by
simply modifying current treatment techniques the levels of chlorinated
organic compounds can be greatly reduced on chlorinated systems. ^ Addi-
tional treatment or different disinfectants may be required.
While there are many unanswered questions at this time, one thing is
certain; a residual disinfectant is required to protect the water in the
distribution system. Also, from our experience, ozone or UV disinfection
cannot provide adequate disinfection on small community water systems. In
addition, the health hazards resulting from the products of ozone or UV
disinfection have not been determined and, in fact, studies in these areas
are only just beginning.
36
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REFERENCES
1. Cornelia, C. Ozone Practice in France. Jour. AWWA, 64:1:39 (Jan. 1972)
2. Bouchard, J. Twenty Years of Ozone in the Treatment of Potable Waters.
Proc. 2nd Int. Symposium on Ozone Tech., Montreal, Canada (1975)
3. Huff, C.B. et al. Study of Ultraviolet Disinfection of Water and Factors
in Treatment Efficiency. Public Health Reports, 80:8:695 (Aug. 1965)
4. Roller, L.R. Ultraviolet Radiation. J. Wiley, New York
5. Jepson, J.D. Disinfection of Water Supplies by Ultraviolet Radiation.
Water Treatment and Examination 64:6:377 (June, 1972)
6. Study of Ultraviolet and Chlorine Water Disinfection Equipment on Board
Passenger Cruise Vessels. U.S. Department of Health, Education, and
Welfare; Public Health Service; Center for Disease Control. Atlanta,
Georgia (Jan. 1977)
7. Final Report of the Drinking Water Disinfection ad hoc Advisory Committee-
March 1, 1977. U.S. Department of Health, Education, and Welfare; Public
Health Service; Center for Disease Control. Atlanta, Georgia
8. Gastrointestinal Illness Aboard a Cruise Ship. Morbidity and Mortality
Weekly Report. 25:39:309
9. Buttolph, L.J. Practical Application and Sources of Ultraviolet Radiation.
Radiation Biology (A. Hollander, Ed.) McGraw-Hill Book Co., New York,
New York (1955) p 455-486
10. Kelner, A. Effects of Visible Light on the Recovery of Streptomyces
griseus conidia from Ultraviolet Irradiation Injury. Proc. Nat'l Acad.
Sci. U.S. 35:73 (1949)
11. Kelner, A. Photoreactivation of Ultraviolet-Irradiated E. Coli. J.
Bact. 58:511-522 (1949)
12. Dulbecco, R. Photoreactivation. Radiation Biology Vol. 2 (A Hollaender
Ed) McGraw Hill Book Company, New York, New York (1955) p 455-486.
13. Carson, L.A. & Peterson, N.J. Photoreactivation of Pseudomona cepacia
after Ultraviolet Exposure: a Potential Source of Contamination in
Ultraviolet-Treated Waters. J. Clinical Micro. 1:5:462 (May 1975)
37
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14. Halldal, A. & Taube, 0. Ultraviolet Action and Photoreactivation in
Algae Photophysiology Vol. 7 (A.C. Giese, Ed.) Academic Press, New
York, New York (1972) p 163-188.
15. Rupert, C.S. Photoreactivation of Ultraviolet Damage Photophysiology
Vol. 2 (A.C. Giese, Ed.) Academic Press, New York, New York (1964)
p 283-327
16. Bartuska, J.F. Ozonation at Whiting: 26 Years Later. Public Works
(1967)
17. Katzenelson, E.; Kletter, F. & Shuval, H.I. Inactivation Kinetics of
Viruses and Bacteria in Water by Use of Ozone. Jour. AWWA 66:12:689
(Dec. 1974)
18. Majumdar, S.B. ; Ceckler, W.H. & Sproul, O.J. Inactivation of Poliovirus
in Water by Ozonation. Jour. WPCF 45:12:2433 (Dec. 1973)
19. O'Donovan, D.C. Treatment With Ozone. Jour. AWWA 57:9:1167 (Sept. 1965)
20. Morin, R.A.; Keller, J.W. & Schaffernoth, T.J. Ozone Pilot Plant Studies
At Laconia, New Hampshire. Symposium on New Trends in Water and Sewage
Treatment Using Pure Oxygen and Ozone. Denver, Colorado October 12, 1974
21. Masschelein, W.; Fransolet, G. & Genot, J. Techniques for Dispersing
and Dissolving Ozone in Water. Water and Sewage Works December 1975,
p 57
22. Nebel, C; Unangst, P.C. & Gottschling, R.D. An Evaluation of Various
Mixing Devices for Dispersing Ozone in Water. Water and Sewage Works
Ref. Number 1973, p R-6
23. Standard Methods for the Examination of Water and Wastewater, 13th
Edition, American Public Health Association, American Water Works
Association, Water Pollution Control Federation, New York, N.Y., (1971)
24. Palin, A.T. Analytical Control of Water Disinfection With Special
Reference to Differential DPD Methods for Chlorine, Chlorine Dioxide,
Bromine, Iodine and Ozone. Jour. Inst. Water Eng. 28:3:139 (May 1974)
25. Hartemann, P.; Block, J.C. & Maugras, M. Biochemical Aspects of the
Toxicity Involved By The Ozone Organic Oxidation Products In Water.
Workshop: Ozone/Chlorine Dioxide Oxidation Products of Organic
Materials. November 17-19 Cincinnati, Ohio
26. Buelow, R.W. & Walton, G. Bacteriological Quality vs. REsidual Chlorine.
Jour. AWWA 63:1:28 (Jan. 1971)
27. Baylis, J.R. & Kuehn, N.H., Jr. Chlorine Residuals - Chicago. Jour.
AWWA 51:2:216 (Feb. 1959)
28. Crabill, M.P. Chlorine Residuals - Indianapolis, Inc. Jour. AWWA,
51:2:221 (Feb. 1959)
38
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29. Policy Statement on Use of the Ultraviolet Process for Disinfection of
Water. U.S. Department of Health, Education, and Welfare; Public Health
Service. Washington, D.C. (April 1, 1966)
30. Hoehn, R.C. Comparative Disinfection Methods. Jour. AWWA. 68:6:302
(June 1976)
31. Recommendations on Vessel Sanitation. Department of Health, Education,
and Welfare; Public Health Service; Center for Disease Control. Atlanta,
Georgia (October 17, 1974)
32. Study of Ultraviolet and Chlorine Water Disinfection Equipment on Board
Passenger Cruise Vessels. U.S. Department of Health, Education, and
Welfare; Public Health Service; Center for Disease Control. Atlanta,
Georgia (Jan. 1977).
33. Gastrointestinal Illness Aboard a Cruise Ship. Morbidity and Mortality
Weekly Report. 25:39:309
34. Rook, J.J. Formation of Haloforms During Chlorination of Natural Waters.
Water Treatment and Examination 23: Part 2:234(1974)
35. Bellar, T.A.; Lichtenberg, J.J. & Kroner, R.C. The Occurrence of
Organohalides in Chlorinated Drinking Water. Jour. AWWA 66:12:703
(Dec. 1974)
36. Rook, J.J. Formation and Occurrence of Chlorinated Organics in Drinking
Water. Presented at the 95th Annual Conference of the American Water
Works Association, June 8-13, 1975, Minneapolis, Minn.
37- Symons, J.M. et. al. National Organics Reconnaissance Survey for
Halogenated Organics in Drinking Water. U.S. Environmental Protection
Agency, National Environmental Research Center, Cincinnati, Ohio (April,
1975)
38. Harris, R.H. The Implications of Cancer-Causing Substances in
Mississippi River Water. A Report by the Environmental Defense Fund,
Washington, D.C. (November 6, 1974)
39. Page, T. ; Harris, R.H. & Epstein, S.S. Drinking Water and Cancer
Mortality in Louisiana. Science. 193:4247:55 (July, 1976)
40. Miller, R.W. Evaluation of the Report by Robert H. Harris, Ph.D.,
of the Environmental Defense Fund on Cancer-Causing Substances in
Mississippi River Water Department of Health, Education, and Welfare;
National Cancer Institute; Epidemiology Branch (Memorandum dated
December 18, 1974).
41. Symons, J.M. et. al. Interim Treatment Guide for the Control of
Chloroform and Other Trihalomethanes. U.S. Environmental Protection
Agency, National Environmental Research Laboratory, Cincinnati, Ohio
(June, 1976)
39
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-79-060
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Ozone and Ultraviolet Radiation Disinfection for
Small Community Water Systems
5. REPORT DATE
July 1979 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Linden E. Witherell, Ray L. Solomon,
Kenneth M. Stone
8. PERFORMING ORGANIZATION REPORT NO
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Vermont State Health Department
Burlington, Vermont 05401
10. PROGRAM ELEMENT NO.
1CC614, SOS #2, Task 6
11. CONTRACT/GRANT NO.
Contract No. 68-03-2182
12. SPONSO~RIN'G'~AG"E"NCY NAME AND"A'DDRESS J' '
Municipal Environmental Research Laboratory—Cin.,OH
Office of Research & Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/600/14
15. SUPPLEMENTARY NOTES
Project Officer: Ralph W. Buelow (513-684-7236)
16. ABSTRACT
Ozone and ultraviolet radiation were used as alternatives to chlorine
for disinfection in several small existing community water systems. Both ozone and
ultraviolet light were found to be inferior to chlorination from the standpoint of
operation and maintenance requirements and maintaining disinfection in the distri-
bution system. A disinfectant residual was found to be necessary even in the small
water distribution systems studied. Neither ozone or ultraviolet provide a
residual disinfectant. The main problem with chlorination in small community water
systems is inadequate operation and maintenance. Inadequate operation and
maintenance is a general problem of small community water systems, not limited to
the disinfection aspect. Methods for improving operation and maintenance of small
water systems need to be established.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Water treatment, Disinfection, Ultra-
violet radiation, Ozonization,
Chlorination, Water supply
Ozonation
Small community water
systems
13B
3. DISTRIBUTION STATEMEN:
Release to Public
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
48
20. SECURITY CLASS (This page}
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
40
US GOVERNMENT PRINTING omcc 1979-6 57-060 / 54 j 1
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