Laboratory Simulation of the Effect of Ozone and Monochloramine on Biofilms in Drinking Water Mains

Chang, Lei; Craik, Steve

doi:10.1080/01919512.2012.686864

Cited by 7 publications

(5 citation statements)

References 15 publications

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“…Several studies describing disinfection strategies were performed using bacteria in the planktonic state but these are inadequate to represent the behavior of those found adhered on surfaces (Mir et al 1997;Khan et al 2017;K€ ohler et al 2018;Forbes et al 2019;Samir et al 2019). Several other works studied DW biofilms formed using reactors operating under conditions far from those found in DWDS, particularly the annular reactor (Chang and Craik 2012), the rotating disc reactor (Murga et al 2001;Pelleïeux et al 2012), and the CDC biofilm reactor (Park and Hu 2010;Abe et al 2011;Armbruster et al 2012). In these reactors the sampling area is modest and biofilms are formed on flat surfaces, which do not mimic the curved geometry of the pipes.…”

Section: Discussionmentioning

confidence: 99%

Influence of surface copper content onStenotrophomonas maltophiliabiofilm control using chlorine and mechanical stress

Gomes

Simões

2020

Biofouling

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This work aimed to evaluate the action of materials with different copper content (0, 57, 96 and 100%) on biofilm formation and control by chlorination and mechanical stress. Stenotrophomonas maltophilia isolated from drinking water was used as a model microorganism and biofilms were developed in a rotating cylinder reactor using realism-based shear stress conditions. Biofilms were characterized phenotypically and exposed to three control strategies: 10 mg l À1 of free chlorine for 10 min, an increased shear stress (a fluid velocity of 1.5 m s À1 for 30s), and a combination of both treatments. These shock treatments were not effective in biofilm control. The benefits from the use of copper surfaces was found essentially in reducing the numbers of non-damaged cells. Copper materials demonstrated better performance in biofilm prevention than chlorine. In general, copper alloys may have a positive public health impact by reducing the number of non-damaged cells in the water delivered after chlorine exposure.

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Section: Discussionmentioning

confidence: 99%

Influence of surface copper content onStenotrophomonas maltophiliabiofilm control using chlorine and mechanical stress

Gomes

Simões

2020

Biofouling

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“…Such way of expressing microbial inactivation is common in the food context (Chang and Craik, 2012). No positive control was prepared, as usual in similar studies (Baumann et al, 2009; Nicholas et al, 2013; de Candia et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

“…In this study, the inactivation data are reported as values of log ( N / N 0 ), that consider both the initial viable counts ( N 0 , untreated control) and the viable counts after the treatment ( N ). Such way of expressing microbial inactivation is common in the food context ( Chang and Craik, 2012 ). No positive control was prepared, as usual in similar studies ( Baumann et al, 2009 ; Nicholas et al, 2013 ; de Candia et al, 2015 ).…”

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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“…For instance ozone has reduced biofilm populations by two orders of magnitude (Chang and Craik 2012), and oral plaque biofilms have been reduced by two orders of magnitude using photodynamic therapy (Wood, Metcalf, Devine and Robinson 2006), but like many other approaches it is unclear how these would be implemented in situ .…”

Section: Discussionmentioning

confidence: 99%

“…Bacteria in biofilms exhibit a markedly different phenotype from planktonic (ie free-floating) bacteria, including a substantial increase in antibiotic resistance (Nickel et al 1985, Vinh and Embil 2005), effectively negating the primary clinical approach of antibiotic administration for bacterial infection. The extracellular polymeric substance (EPS)can act as a transport barrier to larger antimicrobial agents (Drenkard 2003, Fux et al 2003) and act as a reactive sink for oxidizing agents (Chang and Craik 2012, Chen and Stewart 1996), protecting the cells deeper in the film. However, it has become clear that obstruction of biocide transport is not the only resistance mechanism associated with biofilms.…”

Section: Introductionmentioning

confidence: 99%

Thermal mitigation ofPseudomonas aeruginosabiofilms

2015

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Bacterial biofilms infect 2 – 4 % of medical devices upon implantation, resulting in multiple surgeries and increased recovery time due to the very great increase in antibiotic resistance in the biofilm phenotype. This work investigates the feasibility of thermal mitigation of biofilms at physiologically accessible temperatures. Pseudomonas aeruginosa biofilms were cultured to high bacterial density (1.7 × 109 CFU cm−2) and subjected to thermal shocks ranging from 50 °C to 80 °C for durations of 1 to 30 min. The decrease in viable bacteria was closely correlated with an Arrhenius temperature dependence and Weibull-style time dependence, demonstrating up to six orders of magnitude reduction in bacterial load. The bacterial load for films with more conventional initial bacterial densities dropped below quantifiable levels, indicating thermal mitigation as a viable approach to biofilm control.

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Laboratory Simulation of the Effect of Ozone and Monochloramine on Biofilms in Drinking Water Mains

Cited by 7 publications

References 15 publications

Influence of surface copper content onStenotrophomonas maltophiliabiofilm control using chlorine and mechanical stress

Influence of surface copper content onStenotrophomonas maltophiliabiofilm control using chlorine and mechanical stress

Inactivation of Foodborne Bacteria Biofilms by Aqueous and Gaseous Ozone

Thermal mitigation ofPseudomonas aeruginosabiofilms

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