Modelling Approaches for Ozone Processing

Valdramidis, Vasilis; Cullen, Patrick J.; Tiwari, Brijesh K.

doi:10.1002/9781118307472.ch14

Cited by 3 publications

(3 citation statements)

References 62 publications

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“…The presence of a concave curve, and not log-linear as in the case of attached cells, could be linked to the fact that the biofilms, being more mature, are made up of a more heterogeneous cell population in terms of age and therefore of physiology ( Wimpenny et al, 2000 ). The existence of a tail clearly indicates that, as in the case of attached cells, a portion of the microbial population is resistant to treatment, due to inherent or acquired resistances during ozonation treatment ( Valdramidis et al, 2012 ). This behavior related to ozonation treatments was also observed by other authors, although not for sessile microorganisms, i.e., in the form of biofilms ( Brodowska et al, 2017 ).…”

Section: Discussionmentioning

confidence: 99%

Inactivation of Foodborne Bacteria Biofilms by Aqueous and Gaseous Ozone

2018

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In this study, the efficacy of treatments with ozone in water and gaseous ozone against attached cells and microbial biofilms of three foodborne species, Pseudomonas fluorescens, Staphylococcus aureus, and Listeria monocytogenes, was investigated. Biofilms formed on AISI 304 stainless steel coupons from a mixture of three strains (one reference and two wild strains) of each microbial species were subjected to three types of treatment for increasing times: (i) ozonized water (0.5 ppm) by immersion in static condition, (ii) ozonized water under flow conditions, and (iii) gaseous ozone at different concentrations (0.1–20 ppm). The Excel add-in GinaFit tool allowed to estimate the survival curves of attached cells and microbial biofilms, highlighting that, regardless of the treatment, the antimicrobial effect occurred in the first minutes of treatment, while by increasing contact times probably the residual biofilm population acquired greater resistance to ozonation. Treatment with aqueous ozone under static conditions resulted in an estimated viability reduction of 1.61–2.14 Log CFU/cm2 after 20 min, while reduction values were higher (3.26–5.23 Log CFU/cm2) for biofilms treated in dynamic conditions. S. aureus was the most sensitive species to aqueous ozone under dynamic conditions. With regard to the use of gaseous ozone, at low concentrations (up to 0.2 ppm), estimated inactivations of 2.01–2.46 Log CFU/cm2 were obtained after 60 min, while at the highest concentrations a complete inactivation (<10 CFU/cm2) of the biofilms of L. monocytogenes and the reduction of 5.51 and 4.72 Log CFU/cm2 of P. fluorescens and S. aureus respectively after 60 and 20 min were achieved. Considering the results, ozone in water form might be used in daily sanitation protocols at the end of the day or during process downtime, while gaseous ozone might be used for the treatment of confined spaces for longer times (e.g., overnight) and in the absence of personnel, to allow an eco-friendly control of microbial biofilms and consequently reduce the risk of cross-contamination in the food industry.

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Section: Discussionmentioning

confidence: 99%

Inactivation of Foodborne Bacteria Biofilms by Aqueous and Gaseous Ozone

2018

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“…The microbiological quality of food products is an important criterion for applying them in the food industry as well as ensuring consumer safety [ 1 ]. An interest in microbial inactivation by food researchers has expanded for years [ 2 , 3 ]. So far, numerous nonlinear regression analyses have been proposed for different food preservation technologies.…”

Section: Introductionmentioning

confidence: 99%

Modelling the Ozone-Based Treatments for Inactivation of Microorganisms

Brodowska

Nowak

Kondratiuk-Janyska

et al. 2017

IJERPH

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The paper presents the development of a model for ozone treatment in a dynamic bed of different microorganisms (Bacillus subtilis, B. cereus, B. pumilus, Escherichia coli, Pseudomonas fluorescens, Aspergillus niger, Eupenicillium cinnamopurpureum) on a heterogeneous matrix (juniper berries, cardamom seeds) initially treated with numerous ozone doses during various contact times was studied. Taking into account various microorganism susceptibility to ozone, it was of great importance to develop a sufficiently effective ozone dose to preserve food products using different strains based on the microbial model. For this purpose, we have chosen the Weibull model to describe the survival curves of different microorganisms. Based on the results of microorganism survival modelling after ozone treatment and considering the least susceptible strains to ozone, we selected the critical ones. Among tested strains, those from genus Bacillus were recognized as the most critical strains. In particular, B. subtilis and B. pumilus possessed the highest resistance to ozone treatment because the time needed to achieve the lowest level of its survival was the longest (up to 17.04 min and 16.89 min for B. pumilus reduction on juniper berry and cardamom seed matrix, respectively). Ozone treatment allow inactivate microorganisms to achieving lower survival rates by ozone dose (20.0 g O3/m3 O2, with a flow rate of 0.4 L/min) and contact time (up to 20 min). The results demonstrated that a linear correlation between parameters p and k in Weibull distribution, providing an opportunity to calculate a fitted equation of the process.

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“…This equipment can be employed in several applications, such as alkylation reactions, polymerization, hydrogenation, and in the manufacturing of synthetic fuels by gas conversion processes, in fermentation and biochemical processes effluent treatment, Fischer-Tropsch synthesis, and coal liquefaction [12,13]. In liquid treatment applications, ozonation is limited by mass transfer process, fluid dynamics, thermodynamic and design aspects [14,15].…”

Section: Fundamentalmentioning

confidence: 99%

Simplified Models to Describe Transport and Decomposition of Ozone in a Bubble Column

Cremasco¹,

Castilho²

2018

JESE-B

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The understanding of ozonation in bubble columns is the first step to describe this process for organic and inorganic pollutants in water medium in this equipment. This paper developed mathematical models for decomposition of ozone in liquid phase, with analytical solution for zero, first and second-orders kinetics for different pH values, with and without gaseous phase mass transfer effect in the ozone transfer to the liquid phase. The results models are satisfactory when compared with experimental data, and indicate the importance to consider such effects.

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Modelling Approaches for Ozone Processing

Cited by 3 publications

References 62 publications

Inactivation of Foodborne Bacteria Biofilms by Aqueous and Gaseous Ozone

Inactivation of Foodborne Bacteria Biofilms by Aqueous and Gaseous Ozone

Modelling the Ozone-Based Treatments for Inactivation of Microorganisms

Simplified Models to Describe Transport and Decomposition of Ozone in a Bubble Column

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