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Research on Ozone Application as Disinfectant and Action Mechanisms on Wastewater Microorganisms

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Although the use of ozone in wastewater treatment plants is not a common practice, it has been known for over one hundred years. The ozone capacity as wastewater disinfectant was acknowledged in 1886 by Meritens. The first industrial application of ozone in water treatment was performed in 1893 in Holland. Since that time, its use has spread in Europe and the USA. Owing to its oxidizing properties, ozone is currently known as one of the most efficient and fastest microbicides. The evidence has shown that it can break cell membrane or protoplasm, making it impossible to activate bacteria, virus and protozoa cells, removing up to 99% of bacteria and viruses at 10 mg/l in 10 minutes. It attacks mainly unsaturated fatty acids, lipid fatty acids, glycoproteins, glycolipids, amino acids and sulphydryl groups of certain enzymes; DNA is not ozone-resistant. Different studies have shown that ozone can destroy pathogenic and non-pathogenic microorganisms such as: viruses, bacteria, fungi, spores, protozoa, nematodes (helminth eggs) and algae. In this chapter, the results of studies on the application of ozone as disinfectant and its action mechanisms for destroying pathogenic microorganisms are detailed.
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Research on ozone application as disinfectant and action mechanisms on
wastewater microorganisms
M. N. Rojas-Valencia1
1 National Autonomous University of Mexico, Institute of Engineering, Coordination of Environmental Engineering, Post
Box 70-472, Coyoacán 04510, Mexico, D.F. Mexico. Tel. (52) (55) 56233600. E-mail: nrov@iingen.unam.mx.
Although the use of ozone in wastewater treatment plants is not a common practice, it has been known for over one
hundred years. The ozone capacity as wastewater disinfectant was acknowledged in 1886 by Meritens. The first industrial
application of ozone in water treatment was performed in 1893 in Holland. Since that time, its use has spread in Europe
and the USA. Owing to its oxidizing properties, ozone is currently known as one of the most efficient and fastest
microbicides. The evidence has shown that it can break cell membrane or protoplasm, making it impossible to activate
bacteria, virus and protozoa cells, removing up to 99% of bacteria and viruses at 10 mg/l in 10 minutes. It attacks mainly
unsaturated fatty acids, lipid fatty acids, glycoproteins, glycolipids, amino acids and sulphydryl groups of certain enzymes;
DNA is not ozone-resistant. Different studies have shown that ozone can destroy pathogenic and non-pathogenic
microorganisms such as: viruses, bacteria, fungi, spores, protozoa, nematodes (helminth eggs) and algae. In this chapter,
the results of studies on the application of ozone as disinfectant and its action mechanisms for destroying pathogenic
microorganisms are detailed.
Keywords: action mechanisms; disinfectant; ozone; wastewater.
1. Introduction
The capacity of ozone as contaminated water disinfectant was acknowledged in 1886 by Meritens [1]. In 1889, the
French chemist Marius Paul Otto started studying ozone at the University of Paris [2].
In the United States of America, the installed disinfection plants (25 in 1992) have two points of application: as
primary disinfection (for treating trihalomethanes by-products) and as secondary disinfection (for microorganism
removal). In Europe, particularly in France, ozone is used for disinfection at the end of the treatment train and chlorine
can be added for presenting microbiological or algae growth in pipes.
Because of its oxidizing properties, ozone is considered one of the fastest and most efficient known microbicides. It can
break cell membrane or protoplasm, inhabilitating cellular reactivation of bacteria, coliforms, viruses and protozoa,
removing up to 99 % of bacteria and viruses at 10 mg/L in 10 minutes, attacking mainly unsaturated fatty acids, lipid fatty
acids, glycoproteins, glycolipids, amino acids and sulfhydryl groups of some enzymes; DNA is nor ozone resistant [1, 3, 4,
5].
Genera such as: Pseudomonas, Flavobacterium, Streptococcus, Legionella, etc. are some of the bacteria removed
through ozone treatment while among fungi, Candida aspergillus can be mentioned. Hereinafter, the results of studies on
ozone application on viruses, bacteria, fungi, protozoa, helminths and algae are detailed.
2. Viruses
Viruses are small particles considered borderline between live beings and inert matter that can only live and reproduce
parasiting cells and causing their destruction.
Contrary to bacteria, viruses are always harmful and cause diseases such as influenza, cold, measles, small pox,
chicken pox, German measles and poliomyelitis.
Ozone acts on viruses oxidizing the proteins of their envelope and modifying their three-dimensional structure. When
this occurs, the virus cannot anchor itself onto the host cell and thus cannot reproduce and dies. Type II and III viruses
are less resistant and their destruction is complete [6, 3].
Ozone viricide action is observable at lower concentrations than its bactericide action because the viral envelope is
less complex than the bacterial wall. Viruses are generally more ozone resistant than vegetative bacteria but no more
than the sporulated forms such as Mycobacterium.
Table 1 shows the results of ozone application at different doses, temperatures and pHs, contact time (CT) values can
also be seen for inactivating viruses, taken from the US EPA Guideline Documents [7].
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Table 1 Results of ozone application on viruses.
Organisms Dose O3
(mg/L)
Time
(min) Temperature CpH Log Reduction
(%) References
5 10 15 20 25
Polio I
0.4 3
0.4 -1.5
--- --- --- --- --- 7.2 --- 99 [3]
[8]
[5]
Polio II 4-8.5 --- --- --- --- --- --- 7.2 3 99
Polio III --- --- --- --- --- --- --- 7.4 --- 99.5
Rota SA II
V. aughn
--- 0.12-
0.19
<5 --- --- --- --- 6.8 --- 99
V. EEE 0.25 10 --- --- --- --- --- --- --- --- [6]
canine
distemper
virus
0.43 5 --- --- --- --- --- --- --- ---
V. coxsackie 0.51-33 --- --- --- --- --- --- --- 3 --- [3 , 5]
V. porcine 0.024 --- --- --- --- --- --- --- --- --- [3]
Virus
inactivation
0.6 --- 0.6
0.9
1.2
0.5
0.8
1.0
0.3
0.5
0.6
0.3
0.4
0.5
0.15
0.25
0.3
--- 2.0
3.0
4.0
--- [7]
Virus EEE= encephalomyelitis virus. --- = Not reported
3. Fungi
Some types of fungi can cause diseases to human beings. Many others can cause food alteration, turning them
unacceptable for consumption, such as molds, among others. It is thus advantageous to handle and eliminate said
pathogenic forms, the spores of which are found in all types of environments. Ozone eliminates them through its
oxidizing action causing them an irreversible cellular damage as shown in Table 2 [3, 6, 9].
Table 2 Results of ozone application in fungi.
Organisms Dose O3
(mg/L)
Time
(min)
Temperature
(C)
pH Log Reduction
(%)
References
Candida albicans 1.5 10 25 7.2 ---- 99 [10]
Candida parapsilosis ---- ---- ---- ---- ----
Candida aspergillus ---- ---- ---- ---- ----
Clostridium chauvoei
Clostridium tetani
Tricophyton verrucosum
0.8 –2.0 180 20-30 ---- 4
6.8
3.7
---- [6, 9]
Aspergillus flavus 60
11
4
60
---- ---- ---- 78 % [11]
--- = Not registered
4. Spores
Some fungi and bacteria in adverse conditions generate a thick envelope and paralyze their metabolic activity,
remaining in a latent state (spores). When conditions turn favorable, they develop normally and their metabolism
recovers its activity. Said resistance forms are known as spores and are typical of bacteria such as the ones causing
tetanus, gas gangrene, botulism and anthrax.
This resistance mechanism makes it very difficult to fight against them and generally useful treatments such as high
temperatures and the use of antimicrobial agents become inefficient. Ozone at concentrations slightly higher than the
ones used for the rest of bacteria can overcome spores resistance.
5. Bacteria
Since the beginning of the century ozone has been used in water treatment as can be seen in several works registered in
Table 3. Its bactericidal and bacteriostatic effect is obvious at low concentrations ( 0.01 ppm) and during very short
exposition periods.
The following mechanisms are attributed to ozone disinfecting power: lethal oxidation of bacterial protoplasm,
membrane oxidation followed by lysis, cell electron transfer or capture thus irreversibly altering the buffering
mechanism and membrane alteration by ozonolysis of unsaturated fatty acids constituting the external membrane.
Low ozone concentrations and short contact times are sufficient for disinfecting mixed waters. However, it is
impossible to extrapolate results, even less so when the weather condition favors the adaptation and development of a
range of strains from the most diverse genera.
Vibrio cholerae causes cholera, an acute and severe bacterial intestinal disease that has been detected as the cause of
important problems because of its environmental resistance. V. cholerae 01 adapts to chlorine becoming more rugose
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and so does S. typhi [12, 13]. S. typhi is the etiologic agent of typhoid fever. Said pathogen produces an endotoxin
causing fever and diarrhea. An adequate water treatment helps handle said microorganism. As can be seen in Table 3,
the international literature does not have registrations regarding ozone disinfectant evaluation on Salmonella typhi and
Vibrio cholerae 01 found in wastewaters.
Table 3 Results of ozone application on bacteria in different types of water.
Organisms Dose O3
(mg/L)
Time
(min)
Temperature
(C)
pH Log Reduction
(%)
References
Gram-negative bacteria
Escherichia coli 0.6-1
0.01- 2.4 2 – 8.33
12
25 7.2
4 99.99
90
[14]
Staphylococcus sp. 0.6-10 0.5 –0.6 ---- ---- ---- [14]
Pseudomonas aeruginosa 2 0.18 – 4 25 7.2 90 [15]
[16] Pseudomonas flourescens
Streptococcus fecalis 0.6 1 25 – 30 ---- 99 ---- [4]
Mycrobacterium tuberculosis 0.6 6 ---- ---- ---- ---- [4]
Fecal Coliforms
Tertiary effluent
Secondary effluent
Primary effluent
Pretreated water
Pretreated wastewater
Municipal wastewater
2
6-17
20
25-30
30
5-10
0.6
2
5-15
---- ----
2-3
2
1000
(UFC/100
mL)
[4]
[8]
[17]
Total Coliforms
(Municipal wastewater)
5-10 5-15 ---- ---- ---- ---- [18]
Salmonella typhi 0.46-0.78 10 ---- ---- ---- ----
Vibrio cholerae
(Spring water)
0.48-0.84
1.7
15
8
--- ---- ---- 95
100
[13]
Salmonella typhimurium 2.6 3.59 25 7.2 89 [15]
Shigella sonnei 1.35 25 7.2 97
Gram-positive bacteria
Staphylococcus aureus 1.97 10 25 7.2 99 [10]
Streptococcus faecalis 1.97 10 25 7.2 99
Brucella abortus 1.13 60 30 ---- ---- ---- [9]
Pasteurella multocida ---- ---- ----
T. Coliform
F. Coliform
Streptococcus
Salmonella
E. coli
300 20 ---- 7.2 99 [19]
Heterotrophic bacteria
Coliform bacteria
0.1
0.1
1
1
14.3 7.5 1.6
22
97.5
99.4
[20]
C. perfringens 23 5 6.9 5.1 [21]
Bacillus atrophaeus 20 2 25 4 5.25 [22]
--- = Not registered
From previous experience, it is known that ozone can break down cell membranes and protoplasm, and that this process
impedes cell reactivation in bacteria, coliform, virus, and protozoa [1, 5].
Ozone inactivates bacteria by means of oxidation reactions [10]. As can be seen in Figure 2, a) the cell membrane is
the first site under attack; then b) the ozone attacks glycoproteins, glycolipids, or certain aminoacids, and also acts upon
the sulfhydril groups of certain enzymes [5]; c) the effect of ozone on the cell wall begins to become apparent; d) the
bacterial cell begins to break down after being in contact with ozone; e) the cell membrane is perforated during this
process; and finally in f) the cell disintegrates or suffers cellular lysis (see Figure 1).
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Fig. 1. Bacterias undergoing lysis during disinfection with ozone.
5. Protozoa
Protozoa present in their life cycle a vegetative fragile phase (trophozoites) and a more resistant phase (cysts). Cystic
protozoa are much more resistant than viruses and bacteria vegetative forms. Cystic Giardia lamblia has an ozone
sensitivity equivalent to the sensitivity of Mycobacterium sp. sporulated form [1]. Ozone is the most effective
disinfectant for deactivating protozoa such as Cryptosporidium sp. [23, 24]. Cryptosporidium sp. is considered the most
resistant protozoa and is ten times more resistant than Giardia sp. [5].
Ozone destroys protozoa cell membrane. This may be because it affects the wall, making it more permeable. Thus
aqueous ozone enters the cyst and damages the cytoplasmic membrane. Nucleus, ribosome and other structural
components [5] are penetrated. Cryptosporidium sp. concentrations are taken as the disinfection criterion proposed by
the EPA for being one of the most difficult germs to remove [1]. Table 4 shows the results of ozone application on some
protozoa and the time requested for Giardia sp. inactivation using different temperatures.
Table 4. Results of ozone application on some protozoa.
Organisms Dose O3
(mg/L)
Time
(min) Temperature C pH log Reduction
(%)
References
5 10 15 20 25
Giardia lamblia 5-10 0.94- 5 --- ---- ---- ---- ---- 7 1.0 99 [1]
Giardia lamblia
10 ---- 0.32
0.63
0.95
1.3
1.6
1.9
0.23
0.48
0.72
0.95
1.2
1.4
0.16
0.32
0.48
0.63
0.79
0.95
0.12
0.24
0.36
0.48
0.60
0.72
0.08
0.16
0.24
0.32
0.40
0.48
---- 0.5
1.0
1.5
2.0
2.5
3.0
99.9
[7]
[16]
Giardia muris ---- 2.8-12.9 ---- ---- ---- ---- ---- 7 ---- ---- [1]
Cryptosporidium
parvum
50/50
100/0
---- ---- ---- ---- ---- ---- 7 ---- 99 [23]
[24]
Poliphaga sp. ---- 4 ---- ---- ---- ---- ---- ---- ---- 95 [23]
--- = Not registered
Researchers working have found that cystic Giardia lamblia is as sensitive to ozone as the spore form of
Mycobacteria [1]. Ozone has also been demonstrated as the most effective disinfectant for the inactivation of
Cryptosporidium [23], and this is significant because Cryptosporidium is considered the most resistant of the protozoas,
being as much as ten times more resistant than Giardia [5].
In addition to the above, results of experiments with Acanthamoeba sp. (see Figure 5) have demonstrated that these
amoebas have mitochondrias and possess Glutation, as well as the gene for the glutation reductase, and that they
possess Tiol compounds obtained through HPLC. This compound, Tiol, may be the target for the action of ozone
against this parasite, because it has been reported that ozone enters into direct and swift action on the R-HS- sulfur
compounds, with a velocity constant of KO3 = 1.1E106 M-1S-1 in an acid medium.
The survival percentage of each micro-organism resulting from the given CT with ozone, is reported in Table 1. In
all cases, the micro-organisms were very susceptible to ozonation, and a marked reduction of bacterial concentration
was observed. A linear correlation between the logarithm of bacterial concentration (N) and the contact time was found
in all cases, the linear correlation coefficients (r) being significant (α= 0.05) in all experiments (see Figures 2).
a) b)
d) e) f)
c)
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Fig. 2. Tiol compounds obtained in Acanthamoeba sp. by HPLC
7. Algae
The ozonation of algae contaminated water oxides the algae and makes them emerge to the surface. Ozone oxidizes also
the metabolic derivatives of the algae and eliminates undesirable tastes and odors (Richard and Dalga, 1993). Table 5
shows the results of ozone application on some algae using different temperatures and ozone doses, the applied doses
ranging from 1.6 to 3.5 mg/L. Diatoms are the algae most difficult to eliminate obtaining only a 60 % reduction. No
data are available on the temperatures and pH used.
Table 5. Results of ozone application on some genera of algae.
Organisms Dose O3
(mg/L)
Time
(min)
Temperature
C
pH Log Reduction
(%)
References
Phytoplankton total 1.6 8 ---- ---- 1 99.5 [25]
Diatoms
Clorofita
Cyanofita
1.6 8 ---- ---- 1
---- ----
---- ----
Diatoms 2.5-3.5 ---- ---- ---- ---- 60 [26]
Blue green algae
Aphanizomenon
Anabaena
2.5-3.5 ---- ---- ---- ---- 90
--- = Not registered
8. Ozone destruction of helminths eggs
Despite their disinfection resistance, helminths eggs can be removed from water using physical-chemical treatments
such as coagulation flocculation and filtration [27, 28], taking advantage of their size (20 to 100 μm) and their specific
gravity (1 to 1.2). However, although this technique eliminates the water problem, it transfers it to muds, and thus other
alternatives have been studied for destroying helminths eggs [29, 30].
minutes
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Gadomska et al. (1991) [31] used 500 mg O3/hour (8.3 mg O3/L) and observed a helminths eggs reduction of 81.7,
94.6 and 95.7 % with contact times of 45, 90 and 180 minutes, respectively, without mentioning if the destruction was
observed on viable or non-viable eggs.
Rojas and Orta (2000) [32] applied a concentration of 19 mg O3/L (in 500 mL) in gas phase during 30 minutes. They
observed that the disinfectant did not have effect on the structure and viability of A. suum fertile eggs at this dose and
this contact time, because they found mobile larvae inside the egg, as well as in the witness. However, non-viable eggs
were completely destroyed (see table 6).
Table 6. Results of ozone application on Ascaris suum eggs.
Organisms Dose O3 (mg/L) Time
(min) Temperature C pH Reduction
(%)
Observations
Ascaris suum 8.3 180 19-22 -- 81-96 ------
Ascaris suum 18 180 20 -- 94 ------
Ascaris suum 19 30 20 7 90 Non-viable eggs
Source: [31, 32] --- = Not registered
All helminth eggs are morphologically similar. They are also of similar size and chemical constitution. The egg shell
consists of three basic layers that are secreted by the egg itself, namely, a lipoidal inner layer, a chitinous middle layer,
and outer layer of protein (see Figure 3). Their variation mainly depends on the number of amino acids incorporated
into the layers, a result that agrees with the similarity of results obtained when ozone is applied under acid conditions.
During the oxidation process, ozone breaks the wall or shell of helminth eggs. The acid medium causes hydrolysis of
proteins, with amino acids as terminal products. The biphenyls and the quinones are characterized by the presence of
the OH donor group in aromatic nuclei. This donor group is strongly reactive to ozone. Doré (1989) reported velocity
constants for ozonation of cysteine at pH 2, and cystine at pH 1.8, as 3 X 104 and 5,5 X 102 M
-1s-1, respectively,
concluding that sulphur amino acids are highly reactive to ozone. Such observations agree with the results obtained
during this research, using pH 3. At pH 3, after the first hour, a removal rate of 96.7% of Ascaris suum eggs was
achieved. This maximum removal confirms the influence of acid conditions on an increased reactivity of ozone. The
double bond carbon-carbon, plus the sulphur and nitrogen atoms in the lateral chain of the amino acids, also constitute
very selective attack centres for ozone [33].
Figure 3 The egg shell consists of three basic layers: a lipoidal inner layer, a chitinous middle layer, and outer layer
of protein. Results obtained indicated that the degradation of the structure of each amino acid by ozone, depends on the
applied ozone dose. The amino acids which contained a high reactive side chain, were preferentially attacked by ozone.
Fig. 3. The egg shell consists of three basic layers: a lipoidal inner layer, a chitinous middle layer, and outer layer of protein.
Results obtained indicated that the degradation of the structure of each amino acid by ozone, depends on the applied
ozone dose. The amino acids which contained a high reactive side chain, were preferentially attacked by ozone.
It can be stated that ozone shows a significant reaction on the amino acids that form the shell of intestinal parasites,
particularly in an acid pH medium, because the ozone acts upon the nitrogen atom, or upon the R group (alkyl
sulphurated, or insaturated), or on both at the same time. Thus polypeptide or protein reactivity will depend on the
nature of their constituent amino acids.
Using thin-layer chromatography, the following amino acids constituting the shell of Ascaris lumbricoides eggs have
been identified: lysine, arginine, glutamic acid, serine, glycine, cystine, aspartic acid, threonine, alanine, valine,
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tyrosine, leucine, isoleucine, tryptophane, phenylalanine and proline [33]. Results have been identified through liquid
chromatography, show the components that form the external layers of helminth eggs (Figure 4).
Fig. 4. Chromatogram of amino acids constituting the shell of Ascaris lumbricoides eggs. Separation of dansyl amino acids by
HPLC, with UV detection at 250 nm.
Amino acids are symbolized by codes (according to the IUPAC-IUB Commission on Biochemical Nomenclature):
ASP = aspartic acid; GLU= glutamic acid; SER= serine; THR= threonine; GLY= glycine; ALA= alanine; ARG =
arginine; PRO= proline; VAL= valine, MET= methionine; ILE= isoleucine; LEU= leucine; W= tryptophan; PHE=
phenylalanine; CYS= cystine; O= ornithine; LYS= Iysine; TYR= tyrosine.
Background information shows that the ozonation is a viable alternative showing interesting perspectives upon being
applied to water treatment for various purposes.
In conclusion, it can be stated that ozone is a powerful oxidizing agent that can help destroy any type of pathogenic
and non-pathogenic microorganisms.
9. Comparison of cost estimates for the two conventional disinfectants
Costs of chlorine disinfection systems depend on the manufacturer, location and capacity of the treatment plant, and on
the characteristics of the wastewater to be treated.
Hypochlorite compounds, for example, tend to be more expensive than chlorine gas (see Table 5). Nevertheless, many
large cities have chosen to use hypochlorite simply to avoid transporting chlorine gas through built-up areas. In addition
to the costs of chlorination, in some cases it is also necessary to include the cost of dechlorination, because this can
increase the total cost of disinfection by a further 30 to 50 per cent.
Annual costs for running and upkeep in a chlorine disinfection system also include electricity consumption, chemical
compounds and cleaning materials, repair of equipment, and costs for employing personnel. The results of a 1995 study
by the Water Environment Research Foundation, using secondary effluents from disinfection installations with flows of
0.04 to 7.4 m3/s, revealed disinfection costs of $28.14 USD/1000 m3 or 0.02814 USD/m3 for a dose of chlorine of 20
mg/L; and costs of $40.55 USD/1000 m3 or 0.04055 USD/m3 for dechlorination [5].
To compare costs, contact times and the logarithmic reduction for each disinfectant, a dose has first to be established.
The doses necessary for the inactivation of different micro-organisms vary substantially from one disinfectant to
another, and also for the same disinfectant when applied to different micro-organisms (see Table 7).
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Table 7. Comparative summary, results obtained and costs of the two disinfectants applied to tertiary effluents
Disinfectant Micro-
organisms Dose
Contact
Time
(min)
Log
reduc
tion
Method of
disinfection
Costs
USD/ m3 Reference
Chlorine Fecal
Coliforms
5 to 20
(mg/L) 15- 30 4
Hypochlorite 0.0547 Costs calculated
in Mexico
Chlorine gas 0.0292 Costs calculated
in Mexico
Chlorine gas 0.0405 [5]
Ozone Fecal
Coliforms
15
(mg/L) 5 4 Ozone 0.043 [16]
At the present time, in terms of cost, chlorination is more efficient [$0.028 USD/m3] than disinfection with ozone
[$0.043 USD/m3]. However, when de-chlorination is required, this elevates the cost to $0.0427 USD/m3, which
effectively evens out the eventual cost.
From a bibliographic review, it can be said that ozone has the greatest germicidal power, followed by chlorine.
Ozone is 25 times more effective than hypochloric acid (HOCl); 2,500 to 3,000 times more potent and swifter than
hypochlorite (OCl); and 5,000 times better than chloramine (NH2Cl). These results have been measured by comparing
the constants of time against concentration (CT) needed to eliminate 99.99% of all micro-organisms [34].
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... Ozone therapy is based on the assumption that ozone (O3) rapidly dissociates into water and releases a reactive form of oxygen that can oxidize cells, thus having antimicrobial efficacy without inducing drug resistance. Ozone acts on glycolipids, glycoproteins, or certain amino acids, which are present in the cytoplasmic membrane of microorganisms [12][13][14]. The oxidation process of these unsaturated lipids and proteins generates a quantitative conversion of the olefinic bonds present to reactive species (ozonide) of lipid oxidation products [15]. ...
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Introduction: The positive effects of ozone on biological properties include antimicrobial, immunostimulating, and biosynthetic impacts used in the treatment and maintenance of good oral hygiene. Ozone results in alteration in the metabolism of cells by raising the partial pressure of oxygen in tissues which improves the transporting capacity of oxygen in the blood. Ozone causes more blood supply to the ischemic zones due to surgical interventions like tooth extractions and implant placement. In this context of decontamination of root and periapical canals, ozone has emerged as an important sanitizer. Objective: It was to develop a systematic review of the literature to list the main findings of the use of ozone therapy alone or combined with conventional treatments in the treatment of root canals. Methods: The PRISMA Platform systematic review rules were followed. The search was carried out from March to June 2024 in the Scopus, PubMed, Science Direct, Scielo, and Google Scholar databases. The quality of the studies was based on the GRADE instrument and the risk of bias was analyzed according to the Cochrane instrument. Results and Conclusion: A total of 122 articles were found, 35 articles were evaluated in full and 11 were included and developed in the present systematic review study. Considering the Cochrane tool for risk of bias, the overall assessment resulted in 25 studies with a high risk of bias and 22 studies that did not meet GRADE and AMSTAR-2. Most studies did not show homogeneity in their results, with X2=88.5%<50%. Results and Conclusion: It is concluded that ultrasonic and sonic ozone activation resulted in less pain in patients undergoing single-session endodontics compared to no ozone treatment. Ozonated olive oil with zinc oxide and olive oil paste with zinc oxide demonstrated good clinical and radiographic success for pulpectomy of primary teeth. Furthermore, low-intensity laser and ozone therapy are useful methods for postoperative pain in vital symptomatic teeth, but they are not superior to each other.
... The bactericidal and disinfectant power of ozone is widely described in the literature [58][59][60] with its action directed towards the bacterial membrane. In our clinical practice, ozone was applied with a concentration of 10 micrograms immediately after the endolift procedure in order to control inflammation, pain and edema, besides avoiding outbreak of bacteria that could lead to infection cases. ...
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Introduction: The endolift technique has become known for using a laser beam with a 1470 nm wavelength emitted through an optical fiber inserted into the subdermal tissue with the aim of reducing subcutaneous fat and/or toning the skin through neocollagenesis. In Brazil it became popular and commonly called endolaser or endolift laser, as in addition to 1470 nm it also uses a length of 980 nm with the same therapeutic goals. Few complications have been previously reported, most of which include mild and transient erythema, edema, ecchymosis, and nerve palsy. However, the incidence of most serious cases has increased in Brazilian territory. Objective: This study aimed to describe the authors' experience through several cases of complications resulting from endolift or endolaser technique application in Br0061’zil, and which brought to light to some important complications after the procedure. Also, it brings a brief review of the world literature on the subject. Materials and methods: It was carried out exploratory research presented in a narrative review, to highlight the action of the endolift (1470 nm) or endolaser (980 nm) technique used in the treatment of aesthetic dysfunctions. The review explored scientific articles published and available in the following databases: MEDLINE (Online Medical Literature Analysis and Recovery System), PubMed (National Library of Medicine), SCIELO (Scientific Electronic Library Online), LILACS (Latin American Literature and of the Caribbean in Health Sciences), and Google Schoolar. Furthermore, it was were added to this study a series of complications cases from the using endolift/endolaser technique which happened in Brazil in a multicentric manner and developed with the use of various commercially available devices. Results: It was found that the endolift laser technique has the potential to cause important injuries during and after its use when used without suitable criteria for antisepsis, dosimetry and skin temperature controlling. The most common complications described in this study are peripheral neuropathies, burns, local infection and steatonecrosis, the latter considered the main one. However, it was also identified general complications such as hematoma, edema, hyperchromia and optic fiber breaks. Conclusion: Despite the few reports in the world literature, serious secondary complications to the use of subdermal laser using fiber optics (1470 nm and/or 980 nm) are totally possible of happening and have become common in Brazil. Therefore, deserving full attention to the adoption of appropriate application techniques to minimize such complications, among them: greater dosimetric control, adoption of appropriate instruments to better control skin temperature, and greater rigor regarding biosafety measures (mainly antisepsis) when handling the required instrument to perform the technique.
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Ozone is an unstable, naturally occurring gas. The pure gas smells strongly of sulfur and has a gentle sky-blue hue. The molecule comprises three oxygen atoms (O3), and the spacing between them in a cyclical shape is 1.26 Å. It exists in several mesomeric states in dynamic equilibrium. In this chapter, ozone's physical and chemical properties will be addressed, along with its mechanism of microbial inactivation.
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The filtration efficiency of an Advanced Primary Treatment System (APT) was analyzed in terms of suspended solids concentration, particle size distribution and helminth eggs counts. A study was carried out on three one-metre deep sand filters with a specific size (ES) of 0.6, 0.8 and 1.2 mm. More than 50 runs were done with operating rate of 7, 10, 12 and 15 m/h. Basic design-related information was obtained for the APT system. A filter with a 1.2 mm ES provided the best effluent, with 0.1 Helminth egg/L. The average suspended solid concentration in the effluent was 39 mg/L. The most recommendable filtration rate was 10 m/h with a run time of 33 h. A study of the particle distribution was made for each step of the process based on size.
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The plant of Mont-Valérien supplies drinking water to the western suburbs of Paris. The plant has been upgraded, including a preozonation step. The plant has been operated with different doses of ozone applied during the preozonation step, and with different doses of coagulant for clarification. The purpose of that field test was to determine the best operating conditions to obtain the minimum of algae cells in the treated water. The results show that the minimum of algae cell count is obtained when the coagulant dose nullifies the zeta potential, and with an optimum dose of ozone.
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Tophill Low, a water treatment plant supplying the city of Hull, in Yorkshire, England, suffers from water quality problems due to algae and small residuals of pesticides. This plant is due for upgrading, and investigations into new compact processes were carried out to determine a cost-effective (treatment process to meet the current standards. A pilot plant was constructed to determine the efficiency of the Ozoflot® process and results for the removal of algae and oxidation of pesticides are presented, together with data on the formation and reduction of biodegradable organic carbon.
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The City of Indianapolis, Indiana operates two 125 mgd advanced wastewater treatment plants with ozone disinfection. The rated capacity of the oxygen-fed ozone generators is 6,380 Ib/day, which is used to meet geometric mean weekly and monthly disinfection permit limits for decal conforms of 400 and 200 per 100 mL, respectively. Since 1989, a disciplined process monitoring and control program was initiated. Records indicate a significant effect on process performance due to wastewater flow, contactor influent fecal coliform concentration, and ozone demand. Previously, ozone demand information was unknown. Several tasks/studies were performed in order to better control the ozone disinfection process. These include the recent installation of a pilot-scale ozone contactor to allow the plant staff to measure ozone demand on a daily basis. Also, tracer tests were conducted to measure contactor short-circuiting potential. Results demonstrated a noticeable benefit of adding additional baffles. Results also indicated operating strategies that could maximize fecal coliform removal, such as reducing the number of contactors in service at low and moderate flow conditions.