ChapterPDF Available

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

Authors:

Abstract and Figures

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.
Content may be subject to copyright.
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].
263
©FORMATEX 2011
Science against microbial pathogens: communicating current research and technological advances
A. Méndez-Vilas (Ed.)
_______________________________________________________________________________
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
264
©FORMATEX 2011
Science against microbial pathogens: communicating current research and technological advances
A. Méndez-Vilas (Ed.)
______________________________________________________________________________
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).
265
©FORMATEX 2011
Science against microbial pathogens: communicating current research and technological advances
A. Méndez-Vilas (Ed.)
_______________________________________________________________________________
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)
266
©FORMATEX 2011
Science against microbial pathogens: communicating current research and technological advances
A. Méndez-Vilas (Ed.)
______________________________________________________________________________
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
267
©FORMATEX 2011
Science against microbial pathogens: communicating current research and technological advances
A. Méndez-Vilas (Ed.)
_______________________________________________________________________________
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,
268
©FORMATEX 2011
Science against microbial pathogens: communicating current research and technological advances
A. Méndez-Vilas (Ed.)
______________________________________________________________________________
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).
269
©FORMATEX 2011
Science against microbial pathogens: communicating current research and technological advances
A. Méndez-Vilas (Ed.)
_______________________________________________________________________________
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].
References
[1] Langlais, B., Reckhow, D. A., and Brink, D. R. “Ozone in Water Treatment: Applications and Engineering, Cooperative Research
Report (Chelsea, MI, USA: Lewis Publisher, Inc.). Chap. 2: Fundamental Aspects”, p. 43 (1991).
[2] Le Paulouë, J and Langlais, B. “State-of-the-Art of Ozonation in France”. Ozone Sci. Eng. Lewis Publishers. Vol. 21. No. 2, pp.
153-162. (1999).
[3] Garay, P. N and Cohn, F. M. “High – Quality Industrial Water Management” Manual: The Fairmont Press, Georgia. pp. 305 –
324 (1992).
[4] Rakness, K. L; Corsaro, K. M; Hale, G and Blank, B. D. (1993). “Wastewater Disinfection with Ozone Process Management and
Operation Results” Ozone Sci. Eng., Lewis Publishers, Vol. 15 No. 6, pp. 497 – 514 (1993).
[5] US EPA “Guidance Manual: Alternative Disinfectants and Oxidants” (Washington, D.C: Office of Water) Chap. 3: “Ozone”, pp.
7-19 (1999d).
[6] Chávez H., Pérez R., Redondo M. y Baluja C. “Inactivación con ozono de residuales de producciones biotecnológicas. I. Virus
Revista CENCI Ciencias Químicas. Vol. 20 No. 1-2-3, pp. 85-96 (1989a).
[7] US EPA, “Guidance Manual: for Compliance with the Filtration and Disinfection Requirements for Public Water Systems Using
Surface Water Sources”, 1989.
[8] Goncharuk, U.V., Potapchenko, N.G., Sauluk, O.S., Kosinova, V. N. and Sova, A.N. “Disinfection of Water by Ozone: Effect of
Inorganic Impurities on Kinetics of Water Disinfection” J. Water Chem. Technol. Vol. 23 No. 2, pp 55-63 (2001).
[9] Chávez H., Pérez R., Prendes C., Fernández L.A. y Baluja C. “Inactivación con ozono de residuales de producciones
biotecnológicas. III. Bacterias esporuladas y hongos”. Revista CENCI Ciencias Químicas. January-December, Vol. 20 No. 1-2-
3, pp. 104-110 (1989b).
[10] Lezcano, I., Pérez, R. R. , Gutiérrez, S. M., Baluja, Ch. and Sánchez, E. “ Ozone Inactivation of Microorganisms in Water.
Gram positive Bacteria and Yeast” Ozone Sci. Eng. Lewis Publishers. Vol 23, pp. 183-187 (2001).
[11] González M. y Molerio J. “Evaluación de la acción fungicida del ozono frente a Aspergillus flavus y a productos vegetales
contaminados con este hongo”. Revista CENCI Ciencias Químicas. January-December, Vo. 20, No. 1-2-3, pp. 118-121 (1989).
[12] Rice, E. W. “Chlorine and survival of rugose Vibrio cholerae” The Lancet. pp. 340-740 (1992).
[13] Orta, L. M. T., Díaz, P. V. Aparicio, O. G y López, A. “Detección y tratamiento de Vibrio cholerae 01 variedad rugosa
presente en agua”. Memorias del XXVI Congreso Interamericano de Ingeniería Sanitaria y Ambiental of November 1-5. Museo
de la Nación, Lima, Peru. pp. 1-5 (1998a).
[14] Lezcano, I., Pérez, R. R., Sánchez, E and Alvarez, C. “Inactivation con ozono de Pseudomonas aeruginosa y Escherichia coli,
en agua, como modelo de bacterias Gram-negativas” Revista CENIC Ciencias Químicas. Vol. 29, No. 2, pp. 105-108. (1998a).
[15] Lezcano, I., Pérez, R. R. , Gutiérrez, S. M., Sánchez, E and Baluja, Ch. “Inactivation con ozono de Staphylococcus aureus y
Streptococcus faecalis, en agua, como modelo de bacterias Gram-positivas” Revista CENIC Ciencias Químicas. Vol 29, No. 2,
pp. 109-111. (1998b).
[16] Liberti, L., Notarnicola, M. and Lopez, A. “Advanced Treatment for Municipal Wastewater Reuse in Agriculture III: Ozone
Disinfection,” Ozone Sci. Eng. Lewis Publishers. Vol. 22, No. 2, pp. 151-166 (2000).
270
©FORMATEX 2011
Science against microbial pathogens: communicating current research and technological advances
A. Méndez-Vilas (Ed.)
______________________________________________________________________________
[17] Liberti, L., and Notarnicola, M. “Advanced Treatment and Disinfection for Municipal Wastewater Reuse in Agriculture”. Wat.
Sci. Tech. Vol. 40, No. 4-5, pp. 235-245 (1999).
[18] Orta, L. M. T., Monge, R. I.,ñez, I y Rojas, V. N. “Detección, identificación y tratamiento de Vibrio cholerae en agua”. Instituto
de Ingeniería, UNAM. Project 9384. DGAPA IN118198. pp 1-123 (2000).
[19] Yasar, Abdullah, Ahmad, Nasir, Latif, Hummaira and Khan, Aamir Amanat Ali “Pathogen Re-Growth in UASB Effluent
Disinfected By UV, O3, H2O2, and Advanced Oxidation Processes”, Ozone: Science & Engineering, 29: 6, 485 – 492 (2007).
[20] Mark J. Sharrer, Steven T. Summerfelt. “Ozonation followed by ultraviolet irradiation provides effective bacteria inactivation in
a freshwater recirculating system”, Aquacultural Engineering. Vol 37, pp 180–191 (2007).
[21] Lanao, M., Ormad, M. P., Ibarz, C., Miguel, N. and Ovelleiro, J. L. “Bactericidal Effectiveness of O3, O3/H2O2 and O3/TiO2
on Clostridium perfringens”, Ozone: Science & Engineering, 30: 6, 431 – 438 (2008).
[22] Han S. Uhm, Yi F. Hong, Han Y. Lee, Yun H. Park. “Increase in the ozone decay time in acidic ozone water and its effects on
sterilization of biological warfare agents” Journal of Hazardous Materials 168 1595–1601 (2009).
[23] Rennecker J. L., Marióas, B.J., Owens, J.H and Rice, E. W. “Inactivation of Cryptosporidium parvum Oocysts with Ozone”.
Wat. Res. Vol. 33 No. 11, pp. 2481- 2488 (1999).
[24] Driedger, M. A., Rennecker, L.J. and Mariñas, J. B “Sequential Inactivation of Cryptosporidium parvum oocysts with Ozone
and free Chlorine”. Wat. Res. Vol.34 No. 14, pp. 3591-3597 (2000).
[25] Richard Y and Dalga, N. “Preozonation Related to Algae Removal: A Case History: The Plant of Mont- Valérien”, Ozone Sci.
Eng. Vol. 15, No. 5, pp. 445-456 (1993).
[26] Lewis, D.W. Nogueria, J, Faivre, F. M. and Boisdon, V. “The Use of Ozoflotation for the Removal of Algae and Pesticides
from a Stored Lowland Water”. Ozone Sci. Eng. Lewis Publishers. Vol. 15, No. 6, pp. 481-496 (1993).
[27] Jiménez, B., Chávez, A. And Hernández, C. “Alternative Wastewater Treatment Intended for Agricultural”. Wat. Sci. Tech. Vol.
40, No. 4-5, pp. 355-362 (1999).
[28] Landa, H., Capella, A., and Jiménez, B. “Particle Size Distribution in an Effluent From an Advanced Primary Treatment and its
Removal During Filtration” IAWQ. Published by Elsevier Science Ltd. Vol. 97, pp. 159-165 (1997).
[29] Carrington E and S. Harman “The Effect of anaerobic Digestion Temperature and retention Period on the Survival of
Salmonella and Ascaris Ova. En Sewage Sludge Stabilization and Disinfections”. A Bruce (ed), Ellis Horwood Limited, UK.
pp. 369-380 (1984).
[30] Barrios, J. A., Jiménez, B., González, O., Salgado, G., Sanabria, L y Iturbe, R. “Destrucción de coliformes fecales y huevos de
helmintos en lodos fisicoquímicos por vía ácida”. XII Congreso Nacional Ciencia y Conciencia. Morelia, Michoacán, March
21-24 pp. 683-692 (2000).
[31] Gadomska, K., Maleszewska, J., Krogulska, B and Wichrowska, B. “Analysis of Survival Rate of Ascaris suum (Goeze, 1782)
Eggs and of Escherichia coli in Ozone-Desinfected Water”, Bull. Pol. Acad. Sci. Biol. Vol. 39 No. 3, pp. 347-352. (1991).
[32] Rojas, V. N y Orta, L. T. “Resistencia de los Huevos de helmintos a la desinfección con ozono y luz ultra violeta”. Rev. Tláloc-
AMH, April-June No. 18, pp. 23-24 (2000).
[33] Rojas, V. N y Orta, L. T., Mabel Vaca Mier and Víctor-Franco. “Ozonation by-products issued from the destruction of
microorganisms present in wastewaters treated for reuse” Water Science & Technology Vol. 50. No. 2:187–193 © IWA
Publishing 2004 Printed in OK. ISSN 0273-1223. Factor de impacto: 0.710.
[34] Singer, C. P. “Impact of Ozone on the Removal of Particles TOC and THM precursors”, AWWA. (1989)p 1-152.
271
©FORMATEX 2011
Science against microbial pathogens: communicating current research and technological advances
A. Méndez-Vilas (Ed.)
_______________________________________________________________________________
... This study described direct measurements of ozone concentration that could be reached in small and enclosed containers (plastic storage boxes) used as improvised decontamination systems for small items, e.g., disposable personal protective equipment (N95 masks, nitrile gloves, etc.), clothing, small packages, and food. This study also analysed the doses and times required to destroy the virus, mentioning many authors (Farooq and Akhlaque, 1983;Hudson et al., 2009;Li and Wang, 2003;Rojas-Valencia, 2011;Li, 2006, 2008;Zhang et al., 2004;Gray, 2013). ...
... On the other hand, the waste load was considered in the understanding that it was a question of providing the maximum amount of material to simulate the most unfavorable situation. Regarding the effectiveness of the ozone level, it was considered adequate based on the aforementioned literature authors (Dennis et al., 2020;Farooq and Akhlaque, 1983;Hudson et al., 2009;Li and Wang, 2003;Rojas-Valencia, 2011;Li, 2006, 2008;Zhang et al., 2004;Gray, 2013). ...
Article
The Covid-19 pandemic has certainly changed behaviour patterns in many aspects of life, such as the management of solid wastes inside residential spaces. The goal of this research work is to study an ozone generator device as a disinfection and sterilization tool for these wastes in dwellings themselves, thus re-establishing the selective collection to take them back to the recycling chain. In addition, an approach to the risk verification is made. The methodology is based on an experimentation with a device designed to be as cheap as possible. A room like a bedroom is used as a test bed to apply the device, but with no people inside the room to avoid risks. The results show that the device is feasible, concluding that risks are acceptable if its use is correct and appropriate equipment is available to be applied and controlled, all without prejudice of the rigorous control by the competent authorities that approve its use.
... Under this perspective, an additional study based on the removal efficiency of Clostridium perfringens spores as protozoa indicator was carried out. This indicator was selected due to their recent introduction in EU 2020/741 and their resistance to complete removal in conventional tertiary treatments (including chlorine, UV-C light, or even conventional ozonation) as compared with other parasites [61][62][63]. The results showed an average removal percentage of 75 ± 10% during continuous work under optimal conditions (from 800 ± 141 CFU/100 mL in the O 3 /MNBs inlet wastewater). ...
Article
Full-text available
Wastewater treatment plant effluents can be an important source of contamination in agricultural reuse practices, as pharmaceuticals are poorly degraded by conventional treatments and can enter crops, thereby becoming a toxicological risk. Therefore, advanced tertiary treatments are required. Ozone (O3) is a promising alternative due to its capacity to degrade pharmaceutical compounds, together with its disinfecting power. However, mass transfer from the gas to the liquid phase can be a limiting step. A novel alternative for increased ozone efficiency is the combination of micro-nano bubbles (MNBs). However, this is still a fairly unknown method, and there are also many uncertainties regarding their implementation in large-scale systems. In this work, a combined O3/MNBs full-scale system was installed in a WWTP to evaluate the removal efficiency of 12 pharmaceuticals, including COVID-19-related compounds. The results clearly showed that the use of MNBs had a significantly positive contribution to the effects of ozone, reducing energy costs with respect to conventional O3 processes. Workflow and ozone production were key factors for optimizing the system, with the highest efficiencies achieved at 2000 L/h and 15.9 gO3/h, resulting in high agronomic water quality effluents. A first estimation of the transformation products generated was described, jointly with the energy costs required.
... Quality of life is related to the way of understanding and comprehending sensations and meanings attributed by individuals concerning their daily lives and presents a notion of health as "the right to a quality life; health as a right to comprehensive care, with the privilege of promotion and prevention, without prejudice to the recovery and rehabilitation of health conditions; as an expression of the journey of life". Oral health was considered, for the first time, as the quality of life in World War II, when oral well-being was established as a means to assess the individual's suitability for the service [15]. ...
Article
Full-text available
Introduction: The bacterium Staphylococcus aureus is, in most cases, the agent of the disease. Thus, inflammation of the bone marrow can cause compression of the bone tissue walls and decrease or blockage of blood supply in the region's blood vessels, which can induce bone necrosis. Clinical studies have demonstrated the efficiency of ozone therapy in the treatment of peritonitis, infected wounds, and advanced ischemic disease. Objective: It was demonstrate the main scientific findings of the use of antiseptic ozone therapy in endodontic treatment. Methods: The research was carried out from July to October 2022 in 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 127 articles were found, and 57 articles were evaluated and 29 were included in this systematic review. Considering the Cochrane tool for risk of bias, the overall assessment resulted in 10 studies with a high risk of bias and 28 studies that did not meet GRADE. Most studies showed homogeneity in their results, with I2 =96.8% >50%. Ozone therapy is scientifically proven and demonstrated in this work, it proved to be effective for tissue repair and the prevention and treatment of bone necrosis. It was observed that patients undergoing chemotherapy, radiotherapy, and antiresorptive drugs are more affected by bone necrosis. It was also observed the importance of the patient feeling that the treatment works and is restoring his ability to reinvent himself and adapt to his social environment. Treatments should not only be based on established numbers and protocols, without analyzing the specific sensations and perceptions of each patient with their lived reality.
... 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 [8]. Ozone acts on glycolipids, glycoproteins, or certain amino acids, which are present in the cytoplasmic membrane of microorganisms [9]. 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 [10]. ...
Article
Full-text available
Introduction: Issues related to endodontic treatment are intrinsically linked to the prevention and total control of pulp and periapical infections. The presence of microorganisms is not limited to the endodontic but is also present in the periradicular regions, characterized by an apical biofilm that is strongly adhered to the surface. In this context of decontamination of root and periapical canals, ozone has been highlighted as an important sanitizer. Objective: To demonstrate the main experimental and clinical findings of the use of ozone therapy alone and in association with conventional treatments as an antiseptic in the treatment of root canals. Methods: The research was carried out from May 2021 to June 2021 and developed based on Scopus, PubMed, Science Direct, Scielo, and Google Scholar, following the Systematic Review-PRISMA rules. The quality of the studies was based on the GRADE instrument and the risk of bias was analyzed according to the Cochrane instrument. Results: There is moderate evidence to provide important preliminary information about ozone therapy. As for reducing the microbial load for patients undergoing root canal treatment, ozone therapy has inferior results when compared to conventional chemomechanical techniques using NaOCl. The joint action of these treatments proved to be quite effective. Conclusion: Ozone therapy is proving to be a useful new treatment modality that offers great benefits to patients. The strong antimicrobial power of ozone, together with its ability to stimulate the circulatory system and modulate the immune response, makes it a corrective agent of choice in the treatment of various oral infectious diseases. More research is needed to help with its reproducibility, its use should be indicated by the dentist in clinical practice.
... Our [15,16]. The effectiveness of O 3 for killing viruses depends on the relative humidity, temperature, and type of virus, as shown in Dubuis et al. 2020, who reported that a higher effect of low-dose O 3 exposure (0.23-1.23 ppm) for the inactivation of norovirus was found at 85% relative humidity (RH) for 40 min norovirus, while 20% RH for 10 min gave the same result for bacteriophages. ...
Article
Full-text available
Background Ozone (O 3 ) is an effective disinfectant agent that leaves no harmful residues. Due to the global health crisis caused by the COVID-19 pandemic, surgical masks are in high demand, with some needing to be reused in certain regions. This study aims to evaluate the effects of O 3 for pathogen disinfection on reused surgical masks in various conditions. Methods O 3 generators, a modified PZ 2–4 for Air (2000 mg O 3 /L) and a modified PZ 7 –2HO for Air (500 mg O 3 /L), were used together with 1.063 m ³ (0.68 × 0.68 × 2.3 m) and 0.456 m ³ (0.68 × 0.68 × 1.15 m) acrylic boxes as well as a room-sized 56 m ³ (4 × 4 × 3.5 m) box to provide 3 conditions for the disinfection of masks contaminated with enveloped RNA virus (10 ⁵ FFU/mL), bacteria (10 ³ CFU/mL) and fungi (10 ² spores/mL). Results The virucidal effects were 82.99% and 81.70% after 15 min of treatment with 2000 mg/L O 3 at 1.063 m ³ and 500 mg/L O 3 at 0.456 m ³ , respectively. The viral killing effect was increased over time and reached more than 95% after 2 h of incubation in both conditions. By using 2000 mg/L O 3 in a 1.063 m ³ box, the growth of bacteria and fungi was found to be completely inhibited on surgical masks after 30 min and 2 h of treatment, respectively. Using a lower-dose O 3 generator at 500 mg O 3 /L in 0.456 m ³ provided lower efficiency, although the difference was not significant. Using O 3 at 2000 mg O 3 /L or 500 mg O 3 /L in a 56 m ³ room is efficient for the disinfection of all pathogens on the surface of reused surgical masks. Conclusions This study provided the conditions for using O 3 (500–2000 mg/L) to reduce pathogens and disinfect contaminated surgical masks, which might be applied to reduce the inappropriate usage of reused surgical masks.
... Being a gaseous potent oxidant, made up of oxygen only, ozone-based disinfection technology is practical and beneficial compared to other counterparts such as chlorine dioxide, hydrogen peroxide vapors, cold plasma, etc. (Alimohammadi & Naderi, 2021). Ozone is a highly effective disinfectant for almost all kinds of viruses and its ability for disinfection is significantly higher than other disinfectants such as hypochloric acid (25 times), hypochlorite ($3000 times) (Alimohammadi & Naderi, 2021;Moccia et al., 2020;Rojas-Valencia, 2011) and so for hydrogen peroxide (Filippi, 2000). Besides inherent disinfectant characteristics, the interest in using ozone lies in its ability to penetrate spaces easily and revert back into oxygen after use, without releasing toxic by-products (Britton et al., 2020). ...
Article
Full-text available
COVID-19 pandemic has created chaos in almost every walk of life. The harsh impact of the disease is mainly rooted to the rapid and easy spread of SARS-CoV-2 virus through airborne and fomite routes. Thus, disinfection of contaminated surfaces and air is important to hamper COVID-19 disease transmission. Ozone being a potent gaseous disinfectant has been utilized to inactivate a wide-range of viruses and has more recently gained interest in the inactivation of SARS-CoV-2. This article critically reviews the current state-of-knowledge on disinfection of surface-adhered and airborne SARS-CoV-2 by ozone. The transmission and survival characteristics of SARS-CoV-2 alongside the specificity of ozone inactivation process are reviewed. Distinct focus is then given to reviewing the status of ozone inactivation of surface-adhered and airborne SARS-CoV-2 in terms of experimental investigations, kinetics, and influence of the operational factors on the inactivation process. Ozone inactivation of SARS-CoV-2 is compared to other enveloped viruses, and the challenges and future prospects of ozone inactivation of SARS-CoV-2 are also addressed.
... Ozone Ozone is a potent oxidizing agent and it is widely used in the pharmaceutical and food industries as well as in the environmental regulation of pathogenic microorganisms (Table 4.) [29] [30] [31] . In comparison with the chlorine based disinfectants, ozone is 25 times more powerful than Hypo chloric acid (HOCl), and 2,500 to 3,000 times more effective than hypochlorite (OCl − ) [32] . Furthermore, production of ozone gas is easier, more economical, and safer to handle and apply [33] . ...
Article
Full-text available
As Severe acute respiratory syndrome-Coronavirus-2 (SARS-CoV-2) emerged in 2019, scientists sought to find a way of inactivating this new virus to effectively disinfect surfaces, air, hands, etc. The first proposed manners were on the basis of chemical disinfectants such as chlorine and bleach, however, application of these methods can result in some hazards for human beings and the environment. Therefore, new methods such as ultraviolet (UV) radiation were recommended. Not only these new methods can accelerate the inactivation of SARS-CoV-2 in a more efficient way, their hazards and side effects are also less when compared to chlorine-based disinfectants. In this review, we discussed the utilization of UV-C, hydrogen peroxide, ozone, and cold plasma as new, nonthermal methods to disinfect personal protective equipment, air, and surfaces in hospitals, since hospitals were one of the major sources of Coronavirus disease-2019 infection and members of health care team were highly prone to being infected.
... Furthermore, ozone also stands out as an important endodontic antiseptic [22,23]. Ozone acts on glycolipids, glycoproteins, or certain amino acids, which are present in the cytoplasmic membrane of microorganisms [24,25]. In this sense, there is the production of ozonides that have antimicrobial effects [23,25]. ...
Article
Full-text available
Introduction: In the COVID-19 pandemic scenario, in addition to the pathogenesis of SARS-CoV-2, microbial coinfection increases the difficulties of diagnosis, treatment, the prognosis of COVID-19, as well as it can worsen comorbidities and affect the risk of the life of patients. COVID-19 has had a profound impact on dentistry. In addition to endodontic treatment, a management protocol was suggested. Objective: To present the importance of effectively performing endodontic asepsis in the context of the COVID-19 pandemic, to elucidate that infection by the SARS-CoV-2 virus can lead to coinfection, worsening the conditions for endodontic treatment. Methods: The research was carried out from July 2021 to August 2021 and developed based on Scopus, PubMed, Science Direct, Scielo, and Google Scholar, following the Systematic Review-PRISMA rules. The quality of the studies was based on the GRADE instrument and the risk of bias was analyzed according to the Cochrane instrument. Results: A total of 70 articles were found involving the endodontic treatment and COVID-19. A total of 58 articles were evaluated in full and 39 were included and evaluated in the present study. It was found that ozone has high antimicrobial action. N-acetylcysteine (NAC) has a potent effect against endodontic biofilms. Calcium hydroxide is more effective as a root canal disinfectant in primary teeth than formocresol and camphorphenol. The association of 2% chlorhexidine followed by ozone gas for 24 seconds promoted the complete elimination of Candida albicans and Enterococcus faecalis. Low-intensity laser therapy has the property of oral sterilization, facilitating tissue healing and sterilization. Combining antimicrobial photodynamic therapy with antimicrobial irrigants may provide a synergistic effect. Conclusion: There are effective treatments for the sterilization of endodontic tissues, to avoid as much as possible the coinfection with SARS-CoV-2 and the consequent worsening of the infectious condition, highlighting calcium hydroxide, ozone therapy, and laser therapy.
Article
Ozone (O3) is known as the powerful oxidant and has several beneficial applications, especially in biotechnology and agricultural industries. Ozone can be easily created on site with the use of electricity and air. Ozone is a safe antioxidant when used as a substitute to toxic chemical-based pesticides for the storage of grains. As the awareness and preference is augmenting among the people for consumption of organic foods; in this condition, O3 can play the major role as an effective and non-hazardous decontaminant. The O3 has half-life of 20–50 minutes because it rapidly decomposes to diatomic oxygen (O2), and leaving no harmful residue on the surface of grains. The, decayed O3 releases a single O2 atom that is highly reactive towards the cell membrane of bacteria and attacks the cellular components and disrupts normal cellular activity. It has been reported that, O3 at 350 to 600 ppm-h can show highly destructive effects on bacterial and fungal vegetative cells. On the other hand, it is also important to optimize the dose of O3 from species to species and genus of the different bacteria. Some strains of Escherichia coli are resistant to the lower dosage of O3. On overall analysis of scientific opinion and recent outcomes of the laboratory results, we strongly recommend that the use of O3 for the storage of grains should be further investigated and utilized at large scale. Preservation of grains by the use of O3 is also an ecofriendly and considered as a customer-caring method to reduce food pathogens from seed grains without applying any toxic chemicals.
Article
Consumers' awareness toward nutritionally superior foods and improved knowledge of human health have enhanced the inclusion of fruits and vegetables as an integral part of regular dietary intake. However, concerns regarding the safety and quality of foods especially with reference to the outbreak of foodborne illnesses cause a major complication in the consumption of fruits and vegetables. Other major concerns, besides the safety of food from foodborne pathogens, include spoilage due to microbes and chemical pesticide residues. Traditionally, fresh fruits and vegetables are sanitized using chemicals, viz., chlorine, peracetic acid, electrolyzed water, hydrogen peroxide, etc. All these chemicals have been proven to exhibit ill effects over the consumers and the environment over a period of time, and thus, there is a great need for a safe alternative technique, which is eco-friendly and sustainable industrially. Ozone treatment is one such green technology available with multiple benefits such as antimicrobial nature, shelf life extension, pesticide residue removal, starch modification, waste water treatment, and many other industrial applications. It was also approved by FDA as a Generally Recognized As Safe (GRAS) sanitizer because of its eco-friendly nature (degradation into nonharmful oxygen after a short half-life) in addition to its inherent antimicrobial and antiethylene activity. This review focouses on ozone, its mode of action, and its applications in different horticultural crops with potential industrial use. ARTICLE HISTORY
Article
Full-text available
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.
Article
Full-text available
The results of our experiments suggest that the V cholera rugose phenotype represents a fully virulent survival form of the organism that can persist in the presence of free chlorine. The ability of V cholerae to assume this phenotype may limit· the usefulness of chlorination in blocking endemic and epidemic spread of cholera.
Conference Paper
Full-text available
RESUMEN Se estudió la estabilización ácida de lodos fisicoquímicos con altas concentraciones de huevos de helmintos (113.8 huevos/g ST) para producir biosólidos. Se emplearon lodos fisicoquímicos provenientes de la planta de tratamiento de aguas residuales de San Pedro Atocpan (Distrito Federal) con concentraciones de 6.37 a 6.70% de sólidos totales. Los ácidos empleados fueron sulfúrico, perclórico, peracético y acético en dosis de 1,000 a 57,600 ppm dependiendo del ácido. La concentración mínima de huevos de helmintos alcanzada fue de 1.3 huevos viables/g ST empleando ácido acético. En cuanto a coliformes fecales, el ácido peracético logró reducir su densidad por debajo del límite de detección (< 3 NMP/g ST). En todos los casos se cumplió con las densidades requeridas de coliformes fecales para los lodos clase B de acuerdo con la US EPA y la NOM-004-ECOL-2000. INTRODUCCIÓN En la actualidad, el manejo integral de los lodos residuales ha cobrado gran importancia debido al potencial de reúso benéfico que éstos presentan. Dentro de las opciones para reutilizar los lodos, su aplicación en suelos es la práctica más empleada en diversos países de la Comunidad Europea así como en los Estados Unidos, representando aproximadamente 45 y 56% respectivamente (Lue-Hing et al., 1996 y Bastian, 1997). En México su manejo se ha limitado a la disposición en lagunas y rellenos sanitarios principalmente, pero se espera que la tendencia se enfoque al reúso benéfico con la publicación de la Norma Oficial Mexicana NOM-004-ECOL-2000 que establecerá los límites máximos permisibles de contaminantes para los lodos residuales que sean dispuestos o aprovechados. Esta norma regulará el contenido de metales y microorganismos así como la reducción de la atracción de vectores. Para lograr cumplir con los límites de microrganismos que dicha norma establecerá, es necesario aplicar algún proceso de tratamiento que reduzca considerablemente los contenidos de coliformes fecales, Salmonella sp. y huevos de helmintos contenidos en los lodos.
Article
Full-text available
An Advanced Primary Treatment (APT) system commercially known as ACTIFLO®, coupled with a system of filtration and chlorination are described. The system used microsand grains in the coagulation phase. This allowed an almost immediate start-up as well as an increase in loading in the sedimentation tank to rates far higher than those previously described (up to 180 m/h). The process was shown capable of treating wastewater from a combined drainage system, which typically varies in water quality and quantity. The ACTIFLO® process reduced TSS from 354 to 27 mg/L, helminth eggs from 24.8 to 1.2 HE/L, COD from 460 to 198 mg/L, TKN from 21.7 to 18.3 mg/L, and TP-P from 8.7 to 3.2 mg/L. To comply with WHO, 1989 recommendations regarding HE quality in water destined for irrigation of crops eaten raw it is necessary to add to the APT a system of filtration. In the paper two types of filter media are compared. In both cases the HE were reduced to <1.0 HE/L for filtration rates of up to 40 m/h. In the disinfection phase 10 mg Cl2/L were used to reduce the number of fecal coliforms from 6.5 × 108 to 340 MPN/100 mL.
Article
Full-text available
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.
Article
Full-text available
Results of a pilot (100 m/h) investigation on ozone disinfection of municipal tertiary effluents for reuse in agriculture carried out at West Bari (S. Italy) treatment plant are presented. Among dosages, contact times and advanced treatment schemes investigated it was demonstrated that ozone disinfection results in the achievement of the WHO microbial guideline (1,000 CFU/100ml for Fecal Coliforms) for unrestricted wastewater reuse in agriculture of both clarified and clarified-filtered municipal secondary effluents; it is very effective towards Pseudomonas aeruginosa, rather effective towards Giardia lamblia and substantially ineffective towards Cryptosporidium parvum and it forms limited amount of DBP (approx. 350 ppb of total aldehydes). O&M costs amount to 37 Euro/1000m.
Article
The influence of Na+, K+, and Mg2+ cations and SO42-, cl-, HCO3- anions upon the antimicrobial action of ozone in water regarding the test-microorganism Escherichia coli was studied. It was found that Na+, K+, Mg2+ cations and SO42-, Cl- anions which are typical for natural Dniper water did not influence the disinfecting action of ozone. The introduction of HCO3- anions into water (pH > 8.8) results in increasing ozone dose needed for the necessary degree of disinfection being reached due to its decomposition in water.
Article
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.
Article
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.
Article
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.