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HOVEID et al 2008 Ozone for Disinfection of Drinking Water

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HOVEID et al 2008 Ozone for Disinfection of Drinking Water
Archive of SID
1386 ‫ زﻣﺴﺘﺎن‬، ‫ ﺷﻤﺎره دوم‬،‫ﻋـﻠـﻮم ﻣﺤـﯿـﻄﯽ ﺳﺎل ﭘﻨﺠﻢ‬
ENVIRONMENTAL SCIENCES Vol.5, No.2 , Winter 2008
31-38
Evaluating the Use of Ozone for Disinfection of
Drinking Water, Case Study: Tehran Pars Water
Treatment Plant (Iran)
Hassan Hoveid, Gholamreza Nabi Bidhendi, Hamid Reza Jafari,
Touraj Nasrabadi‫٭‬, Toktam Shahriari
Department of Environmental Planning, Faculty of Environment, University of Tehran
Abstract
During recent years, surface water resources
supplying Tehran's potable water – Karaj, Lar and
Jajrood Rivers – are contaminated with different
microorganisms due to population growth.
Additionally, the amount of organic materials
generating odor, taste and color in the surface
water has increased sharply. By considering the
trihalomethane (THM) production potential of
dissolved chlorine in reaction with innocuous
humic substances, future use of chlorine as a
disinfectant in Tehran's drinking water is clouded
in uncertainty. Accordingly, the use of ozone as
another alternative was taken in to consideration
for disinfection of drinking water in this mega
city. In order to evaluate advantages and
disadvantages of water ozonation a pilot with a
generating capacity of 4 gr ozone per hour was
designed. This study was performed between
April and September 2005 and Tehran Pars water
treatment plant in the Northeast of Tehran was
chosen for the case study. Bacteria removal was
considered to be at highest level in all monthly
samples. Different ozone contact times and
dosages were tested in the deactivation of
nematodes and the results showed the perfect
removal in specified periods. Although the initial
investment for construction and implementation of
the required apparatuses is relatively high, since
the raw material for ozone generation is air, the
use of ozone is financially justifiable during the
predicted time of operation. Moreover, the transfer
and storage of ozone is much easier in comparison
with chlorine which is currently in use. Unlike
chlorine, the use of ozone as a disinfectant does
not have the potential of THMs generation. On the
other hand, ozone must be generated on site and is
instable in water. Therefore, a continuous and
precise monitoring and maintenance process must
be taken in to consideration. Furthermore, due to
high corrosive potential of ozone, special resistant
materials must be used in the applied instruments.
Keywords: ozone, water disinfection, Tehran Pars
water treatment plant
‫ارزﯾﺎﺑﯽ اﺳﺘﻔﺎده از ازن در ﮔﻨﺪزداﯾﯽ آب آﺷﺎﻣﯿﺪﻧﯽ‬
‫ ﺗﺼﻔﯿﻪﺧﺎﻧﻪ آب ﺗﻬﺮان ﭘﺎرس‬:‫ﻣﻄﺎﻟﻌﻪ ﻣﻮردي‬
،‫ ﺣﻤﯿﺪرﺿﺎ ﺟﻌﻔﺮي‬،‫ ﻏﻼﻣﺮﺿﺎ ﻧﺒﯽ ﺑﯿﺪﻫﻨﺪي‬،‫ﺣﺴﻦ ﻫﻮﯾﺪي‬
‫ ﺗﮑﺘﻢ ﺷﻬﺮﯾﺎري‬،*‫ﺗﻮرج ﻧﺼﺮآﺑﺎدي‬
‫ داﻧﺸﮕﺎه ﺗﻬﺮان‬،‫ داﻧﺸﮑﺪه ﻣﺤﯿﻂ زﯾﺴﺖ‬،‫ﮔﺮوه ﻃﺮاﺣﯽ ﻣﺤﯿﻂ زﯾﺴﺖ‬
‫ﭼﮑﯿﺪه‬
‫ ﻻر و ﺟﺎﺟﺮود‬،‫ رودﺧﺎﻧﻪﻫﺎي ﮐﺮج‬،‫ ﺑﻪ دﻟﯿﻞ رﺷﺪ ﺟﻤﻌﯿﺖ‬،‫ﻃﯽ ﺳﺎلﻫﺎي اﺧﯿﺮ‬
‫ ﺑـﺎ رﯾﺰﺟﺎﻧـﺪاران‬،‫ﺑﻪ ﻋﻨﻮان ﻣﻨﺎﺑﻊ آب ﺳﻄﺤﯽ ﺗﺄﻣﯿﻦ ﮐﻨﻨﺪه آب ﺷـﺮب ﺗﻬـﺮان‬
‫ ﻃﻌـﻢ و رﻧـﮓ‬،‫ ﻫﻤﭽﻨﯿﻦ ﻣﯿﺰان ﻣﻮاد آﻟﯽ ﻣﻮﻟﺪ ﺑـﻮد‬.‫ﮔﻮﻧﺎﮔﻮﻧﯽ آﻟﻮده ﺷﺪهاﻧﺪ‬
‫ ﺑـﺎ ﺗﻮﺟـﻪ ﺑـﻪ ﭘﺘﺎﺳـﻨﯿﻞ‬.‫در آبﻫﺎي ﺳﻄﺤﯽ اﻓﺰاﯾﺶ ﭼﺸﻢﮔﯿﺮي داﺷـﺘﻪ اﺳـﺖ‬
‫ اﺳﺘﻔﺎده ﻣـﻮﺛﺮ‬،humic ‫ﺗﻮﻟﯿﺪ ﺗﺮي ﻫﺎﻟﻮ ﻣﺘﺎن از واﮐﻨﺶ ﮐﻠﺮﯾﻦ ﻣﺤﻠﻮل ﺑﺎ ﻣﻮاد‬
‫آﺗﯽ از ﮐﻠﺮﯾﻦ ﺑﻪ ﻋﻨﻮان ﻣﺎده ﮔﻨـﺪزداي آب آﺷـﺎﻣﯿﺪﻧﯽ ﺗﻬـﺮان در ﻫﺎﻟـﻪاي از‬
‫ اﺳـﺘﻔﺎده از ازن ﺑـﻪ‬،‫ از اﯾﻦرو‬.(‫اﺑﻬﺎم ﻗﺮار ﻣﯽﮔﯿﺮد )ﺑﺎ ﻋﺪم ﻗﻄﻌﯿﺖ روﺑﺮوﺳﺖ‬
‫ﻋﻨﻮان ﮔﺰﯾﻨﻪاي دﯾﮕﺮ ﺑﺮاي ﮔﻨﺪزداﯾﯽ آب آﺷﺎﻣﯿﺪﻧﯽ ﮐﻼن ﺷﻬﺮ ﺗﻬﺮان ﻣﻮرد‬
‫ ﯾـﮏ‬،‫ ﺑﻪ ﻣﻨﻈﻮر ارزﯾﺎﺑﯽ ﻓﻮاﯾﺪ و ﺿﺮرﻫﺎي ازن زﻧـﯽ آب‬.‫ﺑﺮرﺳﯽ ﻗﺮار ﮔﺮﻓﺖ‬
‫ اﯾـﻦ‬.‫ ﮔﺮم ازن در ﺳﺎﻋﺖ در ﻧﻈﺮ ﮔﺮﻓﺘﻪ ﺷﺪ‬4 ‫ﻣﻮرد آزﻣﺎﯾﺸﯽ ﺑﺎ ﻇﺮﻓﯿﺖ ﺗﻮﻟﯿﺪ‬
‫ اﻧﺠـﺎم ﺷـﺪ و ﺗـﺼﻔﯿﻪ ﺧﺎﻧـﻪ‬1384 ‫ﻣﻄﺎﻟﻌﻪ در دوره زﻣﺎﻧﯽ ﻓﺮوردﯾﻦ ﺗﺎ ﺷﻬﺮﯾﻮر‬
‫ﺗﻬﺮان ﭘﺎرس در ﺷﻤﺎل ﺷﺮﻗﯽ ﺗﻬﺮان ﺑﻪ ﻋﻨﻮان ﻣﮑﺎن آزﻣﺎﯾﺸﯽ ﻣﻄﺎﻟﻌﻪ اﻧﺘﺨـﺎب‬
‫ ﺑﺎﻻﺗﺮﯾﻦ ﺳـﻄﺢ ﺣـﺬب ﺑـﺎﮐﺘﺮيﻫـﺎ در ﻫﻤـﻪ‬،‫ ﺑﻪ ﻣﻨﻈﻮر اﻧﺠﺎم اﯾﻦ ﻣﻄﺎﻟﻌﻪ‬.‫ﺷﺪ‬
‫ زﻣﺎنﻫﺎ و ﻏﻠﻈﺖﻫﺎي ﻣﺘﻔﺎوت ازندﻫـﯽ‬،‫ﻧﻤﻮﻧﻪﻫﺎي ﻣﺎﻫﯿﺎﻧﻪ در ﻧﻈﺮ ﮔﺮﻓﺘﻪ ﺷﺪ‬
‫ ﺣـﺬف ﮐﺎﻣـﻞ ﺑـﺎﮐﺘﺮيﻫـﺎ در‬،‫در ﺧﻨﺜﯽﺳﺎزي ﻧﻤﺎﺗﻮدﻫﺎ آزﻣﺎﯾﺶ ﺷﺪ و ﻧﺘﺎﯾﺞ‬
‫ ﺑﺎ وﺟﻮد اﯾﻦﮐﻪ ﺳﺮﻣﺎﯾﻪﮔﺬاري اوﻟﯿـﻪ ﺑـﺮاي‬.‫دوره ﻫﺎي ﺗﻌﯿﯿﻦ ﺷﺪه را ﻧﺸﺎن داد‬
‫اﺣﺪاث و ﺑﻬﺮه ﺑﺮداري از دﺳﺘﮕﺎهﻫﺎ و ﺗﺠﻬﯿﺰات ﻣﻮرد ﻧﯿﺎز از ﺟﻤﻠﻪ ﻣـﻮاد ﺧـﺎم‬
‫ اﻣــﺎ اﺳـﺘﻔﺎده از ازن در ﻃـﻮل زﻣــﺎن‬،‫ﺑـﺮاي ﺗﻮﻟﯿـﺪ ازن در ﻫــﻮا ﻧـﺴﺒﺘﺎً ﺑﺎﻻﺳـﺖ‬
‫ اﻧﺘﻘـﺎل و‬،‫ ﻋـﻼوه ﺑـﺮ اﯾـﻦ‬.‫ﭘﯿﺶ ﺑﯿﻨﯽ ﺷﺪه ﺑﻬﺮه ﺑﺮداري ﺗﻮﺟﯿـﻪ اﻗﺘـﺼﺎدي دارد‬
،‫ذﺧﯿﺮه ازن ﻧﺴﺒﺖ ﺑﻪ ﮐﻠﺮﯾﻦ ﮐﻪ در ﺣﺎل ﺣﺎﺿﺮ ﻣﻮرد اﺳﺘﻔﺎده ﻗـﺮار ﻣـﯽﮔﯿـﺮد‬
‫آﺳﺎن ﺗﺮ اﺳﺖ و اﺳﺘﻔﺎده از ازن در ﻣﻘﺎﯾﺴﻪ ﺑﺎ ﮐﻠﺮﯾﻦ از ﭘﺘﺎﻧﺴﯿﻞ ﺗﻮﻟﯿﺪ ﺗﺮي ﻫﺎﻟﻮ‬
‫ ﺗﻮﻟﯿﺪ ﺷـﻮد و‬،‫ از ﺳﻮي دﯾﮕﺮ ازن ﺑﺎﯾﺪ در ﻣﺤﻞ‬.‫ﻣﺘﺎن ﮐﻤﺘﺮي ﺑﺮﺧﻮردار اﺳﺖ‬
‫از ﺛﺒﺎت )ﻣﺎﻧﺪﮔﺎري( ﮐﻤﺘﺮي در آب ﺑﺮﺧﻮردار اﺳﺖ و ﺑﻨﺎﺑﺮاﯾﻦ اﺗﺨﺎذ ﻓﺮاﯾﻨـﺪ‬
‫ ﻋﻼوه ﺑﺮ ﻣـﻮارد ﯾﺎدﺷـﺪه ﺑـﻪ‬.‫ﻧﮕﻬﺪاري و ﭘﺎﯾﺶ دﻗﯿﻖ و ﻣﺪاوم ﺿﺮوري اﺳﺖ‬
‫ ﺑﺎﯾﺪ ﻣﻮادي ﺑﺎ ﻣﻘﺎوﻣﺖﻫﺎي وﯾﮋه در اﺑﺰار‬،‫دﻟﯿﻞ ﭘﺘﺎﻧﺴﯿﻞ ﺧﻮرﻧﺪﮔﯽ ﺑﺎﻻي ازن‬
.‫ﮐﺎرﺑﺮدي اﺳﺘﻔﺎده ﺷﻮد‬
.‫ ﺗﺼﻔﯿﻪ ﺧﺎﻧﻪ آب ﺗﻬﺮان ﭘﺎرس‬،‫ ﮔﻨﺪزداﯾﯽ آب‬:‫ﮐﻠﯿﺪواژهﻫﺎ‬
* Corresponding author. E-mail Address: [email protected]
1386 ‫ زﻣﺴﺘﺎن‬،‫ ﺷﻤﺎره دوم‬،‫ﻋـﻠـﻮم ﻣﺤـﯿـﻄﯽ ﺳﺎل ﭘﻨﺠﻢ‬
ENVIRONMENTAL SCIENCES Vol.5, No.2 , Winter 2008
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Archive of SID
Introduction
demanding materials in solution will render the half-
Globally, surface water and ground water are
life even shorter (Rice et al., 1979).
important sources for drinking water production
Ozone is widely used in drinking water treatment
(Heberer, 2002a; Heberer, 2002b; Hua et al., 2006).
practice in Europe, its first application having been in
Disinfection, one of the unavoidable stages in water
1893 at Oudshoorn in The Netherlands. Today more
treatment, is defined as the destruction of pathogenic
than 1,000 plants throughout the world use ozone.
microorganisms. It does not apply to non-pathogenic
Canada has 22 plants and Montreal has probably the
microorganisms or to pathogens that might be in the
world's largest (Rice et al., 1979).
spore state (McCarthy and Smith, 1974). Chlorine is
Ozone must be produced on-site because it can not
the most widely used disinfectant because it is
be stored as chlorine can. This is not necessarily bad;
effective at low concentrations, is cheap and forms a
serious accidents have happened with chlorine because
residual if applied in sufficient dosage. It may be
of breaks in storage systems. Ozone is produced by
applied as a gas or as a hypochlorite, the gas form
passing air between oppositely charged plates or
being more common. The disinfecting ability of
through tubes in which a core and the tube walls serve
chlorine is due to its powerful oxidizing properties,
as the oppositely charged surfaces. Air is refrigerated
which oxidize those enzymes of microbial cells that
to below the dew point to remove much of the
are essential to the cells' metabolic processes (Hammer
atmospheric humidity and then is passed through
and Hammer, 2004). Reaction of chlorine with
desiccants such as silica gel, activated alumina to dry
innocuous humic substances results in the formation of
the air to a dew point of -40 to -60 degrees centigrade.
trihalomethanes including chloroform, bromoform,
The use of dry and clean air results in less frequent
bromodichloromethane and dibromochloromethane.
ozone generator maintenance, long-life units and more
These compounds are limited by drinking water
ozone production per unit of power used (Jolley,
regulations to a total of .1 miligram per liter because
1975).
Ozone
of tumorigenic properties (White, 1998). Conventional
sterilizes
water
and
removes
all
as
microorganisms including microbes, viruses, amebas,
coagulation/flocculation, filtration, and chlorination
etc. in a short period of time (Qasim et al., 2002).
are largely ineffective in removing some specific
Being a powerful oxidant, it oxidizes all humic
pollutants (Ternes et al., 2002; Verstraeten et al.,
compounds in addition to iron and manganese and
2002). Ozone (O3) has traditionally been applied in
consequently
drinking
completely and color up to 60%.
drinking
water
water
treatment
treatment
processes
plants
such
(WTPs)
for
decreases
water
taste
and
odor
disinfection and oxidation (e.g. decoloration, taste and
During recent years, surface water resources
odor control, elimination of micropollutants, etc.)
supplying Tehran's potable water – Karaj, Lar and
(Von Gunten, 2003a; Hijnen et al., 2001). However,
Jajrood Rivers – have been contaminated with
the benefits of treatment by ozone are unfortunately
different microorganisms due to population growth.
accompanied by the oxidation of bromide to bromate
Additionally, the amount of organic materials
which is classified as a potential human carcinogen
generating odor, taste and color in surface water has
(von Gunten, 2003b; Meunier et al., 2006; Smeets et
been increasing sharply. By considering the THM
al., 2006). Ozone is an allotrope of oxygen. It is a
production potential of dissolved chlorine in reaction
powerful oxidant and is more powerful than chlorine
with innocuous humic substances, future use of
and other oxidants. In aqueous solution it is relatively
chlorine as a disinfectant in Tehran's drinking water is
unstable, having a half-life of 20 to 30 minutes at 20
clouded in uncertainty. Accordingly, the use of ozone
degrees
centigrade.
The
presence
of
oxidant-
1386 ‫ زﻣﺴﺘﺎن‬،‫ ﺷﻤﺎره دوم‬،‫ﻋـﻠـﻮم ﻣﺤـﯿـﻄﯽ ﺳﺎل ﭘﻨﺠﻢ‬
ENVIRONMENTAL SCIENCES Vol.5, No.2 , Winter 2008
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Archive of SID
as another alternative was taken in to consideration for
disinfection of drinking water in this city.
September 2005 and Tehran Pars water treatment plant
In this study the use of ozone as a water
disinfectant
is
taken
in
to
consideration
This study was performed between April and
was chosen for the case study. This water treatment
for
plant is located in the Northeast of Tehran and its
disinfection of drinking water in the mega city of
water supply is provided via the Lar and Jajrood
Tehran.
Rivers. This water treatment plant has been used since
1983 and, currently, dissolved chlorine is used for
Materials and Methods
disinfection in this treatment plant. Particularly .6 and
In order to evaluate advantages and disadvantages of
1 milligrams per liter is injected for pre-chlorination
water ozonation a pilot with a generating capacity of 4
and chlorination respectively.
gr ozone per hour was designed. As ozone is in gas
Results and Discussion
form and its addition to water in precise measures is so
difficult in bench scale, the saturated solution of ozone
Sampling was carried out in order to evaluate
in water was applied instead. Considering ozone
the influence of ozone in the deactivation of bacteria
instability in water, the pilot was designed in such a
and parameters like total coliforms in most probable
way that dissolved ozone is easily added to samples
number (MPN), fecal streptococci in MPN and
with no contact by atmosphere. A simplified schematic
heterotrophic bacteria in colony forming units per
view of the pilot is given in Figure 1. The ozone
milliliter (CFU/ml) were measured in proportion to the
generator pumps the ozone to a chamber having a
amount and contact time of ozone. The results are
volume of 4 liters. After being mixed with the entered
shown in Table 1.
ozone, the water sample is sent to a 6-liter reactor.
Figure1- Designed pilot for water ozonation
1386 ‫ زﻣﺴﺘﺎن‬،‫ ﺷﻤﺎره دوم‬،‫ﻋـﻠـﻮم ﻣﺤـﯿـﻄﯽ ﺳﺎل ﭘﻨﺠﻢ‬
ENVIRONMENTAL SCIENCES Vol.5, No.2 , Winter 2008
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Table 1- Effect of ozone with concentration of 1 ppm in deactivation of different bacteria
Sample
Contact Time
(Min)
Residual
Ozon
(ppm)
Total Coliform
Bacteria
(MPN/100ml)
Blank
1
Fecal Streptococci
(MPN/100ml)
Heterotrophic
Bacteria
(CFU/ml)
----
----
4
.55
>1600
900
>6500
16.1
>1.1
>25
2
5
.4
2.2
>1.1
10
3
10
.3
1.1
>1.1
----
4
12
.3
1.1
>1.1
----
In Figures 2 to 5 the percentage of bacteria
be seen in these figures, bacteria removal is at its
removed and residual ozone are illustrated for
highest level in all cases.
different amounts and contact times of ozone. As can
100
80
60
% Bacteria Removal
40
% Residual Ozone
20
0
Coliform
Bacteria
Streptococci
Bacteria
Heterotrophic
Bacteria
Figure 2- Percentage of bacteria removal in a 4-minute contact time and ozone concentration of 1 ppm
100
90
80
70
60
50
% Bacteria Removal
40
30
20
% Residual Ozone
10
0
Coliform
Bacteria
Streptococci Heterotrophic
Bacteria
Bacteria
Figure 3- Percentage of bacteria removal in a 5-minute contact time and ozone concentration of 1 ppm
1386 ‫ زﻣﺴﺘﺎن‬،‫ ﺷﻤﺎره دوم‬،‫ﻋـﻠـﻮم ﻣﺤـﯿـﻄﯽ ﺳﺎل ﭘﻨﺠﻢ‬
ENVIRONMENTAL SCIENCES Vol.5, No.2 , Winter 2008
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100
90
80
70
60
50
40
30
20
10
0
% Bacteria Removal
% Residual Ozone
Coliform
Bacteria
Streptococci
Bacteria
Heterotrophic
Bacteria
Figure 4- Percentage of bacteria removal in a 10-minute contact time and ozone concentration of 1 ppm
100
90
80
70
60
50
% Bacteria Removal
40
% Residual Ozone
30
20
10
0
Coliform
Bacteria
Streptococci
Bacteria
Heterotrophic
Bacteria
Figure 5- Percentage of bacteria removal in a 12-minute contact time and ozone concentration of 1 ppm
Nematodes are among the most tolerant
many factors including initial concentration of
microorganisms in water because of their coticoul
bromide in water, pH, etc. Ozone is a major factor
membrane. Chlorine in low dosages is incapable of
which reinforces the conversion of bromide to
removing them. Accordingly, in evaluating the
bromated compounds. Accordingly, the measurement
efficiency of ozone in water disinfection these
of bromide and bromate was applied after a five-
microorganisms have been considered as indexes.
Different ozone contact times and dosages were tested
in deactivation of nematodes in the samples (6 liters)
and the results are shown in Table2.
Formation of bromated compounds in water –
which are considered to be carcinogenic – depends on
minute contact time of ozone which is a common
period of time in ozonation. The results are given in
Table 3. As is indicated, the concentration of bromate
is more than the maximum contaminant level (MCL)
entitled US EPA.
1386 ‫ زﻣﺴﺘﺎن‬،‫ ﺷﻤﺎره دوم‬،‫ﻋـﻠـﻮم ﻣﺤـﯿـﻄﯽ ﺳﺎل ﭘﻨﺠﻢ‬
ENVIRONMENTAL SCIENCES Vol.5, No.2 , Winter 2008
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Table 2- Influence of ozone on nematode removal
Sample
Ozone
Ozone
concentration
residual after
(ppm)
5 min (ppm)
Number of
Number of
Number of
Percentage of
be taken in to consideration. Furthermore, due to the
nematodes in
living
dead
nematodes
samples
nematodes
nematodes
after
after
removal
ozonation
ozonation
Blank
0
0
286
286
0
0
1
2.5
.2
316
43
273
86
2
2.75
.5
257
7
250
97
3
3
.7
276
5
271
98
4
3.25
1.4
262
2
260
99
5
3.25
1.9
190
0
190
100
Table 3- Results of bromate generation as a consequence of ozonation
Sample
Date
pH
Turbidity
T (ºC)
(NTU)
Bromide
Residual
Generated
Brom to
mg/l
ozone
Bromate
Bromate
after 5
mg/l
min
conversion
efficiency %
(mg/l)
1
April
8.4
.6
23
.4
2
.25
39
2
July
8.2
1.5
24
.5
1.6
.35
44
3
Sept.
8.3
1.5
21
.5
.8
.36
45
Conclusion
Although the initial investment for construction and
high corrosive potential of ozone, particular resistant
implementation of the required equipments is
materials must be used in applied instruments.
relatively high, since the raw material for ozone
According to the data achieved, use of ozone as
generation is air the use of ozone can be justified
a disinfectant is extremely efficient in the removal of
financially during the predicted time of operation.
different kinds of bacteria including total coliforms,
Moreover, transfer and storage of ozone is much easier
fecal streptococci and heterotrophic bacteria as well as
in comparison with chlorine which is currently in use.
nematodes. Similar results have been reported by
Unlike chlorine, use of ozone as a disinfectant
different authors; Gomella and co-workers have also
does not have the potential of trihalomethanes (THMs)
observed complete destruction of poliovirus samples
generation (Chang et al., 1991). Additionally, in the
in distilled water at a residual of .3 mg/ l at the end of
case of MTBE existing in the water of an over-
3 minutes of exposure to ozone. They then observed
polluted city like Tehran, ozone has the potential for
the same effectiveness when the viruses were
removing it.
suspended in Seine River water, and recommended the
On the other hand, ozone must be generated on-
use of .4 mg/ l after a contact of four minutes
site and is unstable in water. Therefore, a continuous
(Cheremisinof, 2002). However, testing some shorter
and precise monitoring and maintenance process must
ozone contact times or even thinner concentrations of
ozone is also suggested for further studies.
1386 ‫ زﻣﺴﺘﺎن‬،‫ ﺷﻤﺎره دوم‬،‫ﻋـﻠـﻮم ﻣﺤـﯿـﻄﯽ ﺳﺎل ﭘﻨﺠﻢ‬
ENVIRONMENTAL SCIENCES Vol.5, No.2 , Winter 2008
¡ 36 ¡
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Archive of SID
Use of ozone decreases sharply the required time
for
flocculation
and
coagulation.
Heberer,
Furthermore,
T.
(2002a).
Tracking
persistent
pharmaceutical residues from municipal sewage
to drinking water, J. Hydrol., 266: 175–189.
increasing the efficiency of filtration up to 50%, use of
ozone decreases sludge generation rate in back wash
of filters. The only limiting factor in the usage of
Heberer, T. (2002b). Occurrence, fate, and removal of
ozone as a disinfectant in the Tehran Pars water
pharmaceutical
treatment plant is the existence of bromide in feed
environment: a review of recent research data,
water. Further studies are recommended by the authors
Toxicol. Lett. 131: 5–17.
for the determination of the bromated compounds
formation potential of water ozonation in this plant.
full-scale ozonation of the River-lake waterworks
of Amsterdam Water Supply. In: Proceedings of
identifying by-products of the reaction of ozone with
the International Ozone Association Congress,
organic materials. The formation of several persistent,
September 2001, London.
potentially dangerous epoxies has been predicted by
health
and
environmental
aquatic
Improvement of the disinfection efficiency of the
Different researches have been directed toward
human
the
Hofman, A.D. Bosch, G. J. Medema (2001).
about the reaction of ozone with organic materials.
significant
in
Hijnen, W. A. M., Th.G.J. Bosklopper, J. A.M.H.
It should be noted that there are uncertainties
ozone reaction models. These by-products may have
residues
Hua, W., E.R. Bennett, R.J. Letcher (2006). Ozone
treatment and the depletion of detectable
consequences that will influence the use of ozone for
pharmaceuticals
water disinfection.
and
atrazine
herbicide
in
drinking water sourced from the upper Detroit
As a future study, a cost-benefit research on the
River, Ontario, Canada, Water Res. 40(12), 2259-
use of ozone and chlorine for disinfection of Tehran's
2266.
drinking water in different water treatment plants is
suggested. Additionally, a parallel study on the
Jolley, R. L. (1975). Chlorine-Containing Organic
adverse effects of THMs and bromated compounds in
Constituents in Chlorinated Effluents, Journal
drinking water of Tehran is also recommended.
Water Pollution Control Federation (WPCF),
47(3):601.
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1386 ‫ زﻣﺴﺘﺎن‬،‫ ﺷﻤﺎره دوم‬،‫ﻋـﻠـﻮم ﻣﺤـﯿـﻄﯽ ﺳﺎل ﭘﻨﺠﻢ‬
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