Photoreactivation of UV-irradiated Legionella pneumophila and other Legionella species

Knudson, Gregory B.

doi:10.1128/aem.49.4.975-980.1985

Cited by 64 publications

(29 citation statements)

References 39 publications

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“…Damage to bacterial DNA caused by UV irradiation may be repaired by either photoreactivation or dark repair (Knudson, 1985). However, viruses need the host enzymes to repair the UV damage; moreover Cryptosporidium and Giardia do not regain infectivity after inactivation by UV light (Shin et al, 2001;Linden et al, 2002).…”

Section: Tertiary Treatment In Pp: Uv Irradiation and Chlorinationmentioning

confidence: 99%

UV disinfection of wastewater effluents for unrestricted irrigation

Nasser

Paulman

Sela

et al. 2006

Water Science and Technology

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Wastewater reuse in arid regions is important for the production of a water resource to be utilised for non-potable purposes and to prevent the environmental transmission of disease-causing agents. This study was conducted to evaluate the effect of water quality on the comparative disinfection efficiency of viruses, bacteria and spores by UV irradiation. Furthermore, the microbial quality of effluent produced by coagulation, high rate filtration (HRF) and either UV irradiation or chlorination was determined. Using low pressure collimated beam, a UV dose of 80 mWs/cm2 was needed to achieve a 3-log10 inactivation of either rotavirus SA-11 or coliphage MS2, whereas over 5-log10 inactivation of E. coli was reached with a dose of only 20 mWs/cm2. B. subtilis inactivation was found to be linear up to a dose of 40 mWs/cm2 and then a tailing up to a UV dose of 120 mWs/cm2 was observed. It is worth noting that effluent turbidity of < 5 NTU did not influence the inactivation efficiency of UV irradiation. Operation of a pilot plant to treat secondary effluent by coagulation, HRF and UV disinfection at a UV dose of 80 mWs/cm2 resulted in the production of high quality effluent in compliance with the Israel standards for unrestricted irrigation (< 10 CFU/100 mL faecal coliform and turbidity of < 5 NTU). Sulphite reducing clostridia (SRC) were found to be more resistant than coliphages and F coliform for UV irradiation. The results of this study indicated that UV disinfection is suitable for the production of effluents for unrestricted irrigation of food crops.

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Section: Tertiary Treatment In Pp: Uv Irradiation and Chlorinationmentioning

confidence: 99%

UV disinfection of wastewater effluents for unrestricted irrigation

Nasser

Paulman

Sela

et al. 2006

Water Science and Technology

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“…Not available Gehr and Nicell (1996) FC Sunlight 2.5 hours ;1 ;0.5 Harris et al (1987) EC, SF Lamps 2 hours 3.4 (EC); 2.4 (SF) Not available Kashimida et al (1996) EC, TC, FC Sunlight 0 to 1.5 hours ;1 (maximum at 15 minutes) ;0 Lamps 0 to 2 hours ;1.5 (TC, FC, maximum at 2 hours) ;0 Knudson (1985) EC EC (7 strains) Lamps 0 to 2 hours 1 to 3.4 (maximum at 2 hours) ;0 Whitby et al (1984) TC, FC, FS Sunlight 0 to 6 hours 1 (TC, FC); 0 (FS) ;0 Zimmer and Slawson (2002) EC Lamps 0 to 4 hours 0.7 to 2.8 (maximum at 3 hours; LP) ;0 * Note: TC 5 total coliform, FC 5 fecal coliform, FS 5 fecal streptococci, EC 5 E. coli, SF 5 S. faecalis, and LP 5 low-pressure UV lamps.…”

Section: Introductionmentioning

confidence: 99%

Reduction of Photoreactivation with the Combined UV/Peracetic Acid Process or by Delayed Exposure to Visible Light

Martín¹,

Gehr²

2007

Water Environment Research

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Photoreactivation of microorganisms following UV inactivation is a well‐known, but complex, phenomenon. It is affected by several factors, including UV fluence, wavelength, light intensity, and exposure time to photoreactivating light. The effect on photoreactivation of a combined peracetic acid (PAA)/UV process has not been investigated. Accordingly, this study compared the degree of photoreactivation, under both sunlight and artificial lights, following UV and combined PAA/UV inactivation of fecal coliforms.    Effluent samples from the Montreal Wastewater Treatment Plant (MWTP) (Quebec, Canada) were exposed, for 3 hours, to both low‐ and high‐intensity artificial lights and sunlight. All resulted in similar photoreactivation levels. However, average photoreactivation for UV‐treated wastewater samples was 1.2 logs, compared with 0.1 log for the combined PAA/UV treatment. Hence, the use of PAA in combination with UV can significantly reduce the potential for photoreactivation.    To simulate the photoreactivation conditions of the MWTP effluent (which passes through a 4‐km outfall tunnel with approximately 3 hours detention time), UV‐treated samples were kept in the dark for 3 hours before photoreactivating light exposure. After this period, photoreactivation levels were close to zero. Hence, the effects of photoreactivation may be diminished by use of a combined disinfection scheme and/or by delaying exposure of the disinfected wastewater to light.

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“…To eradicate legionellae in cooling tower water, several methods, including ultraviolet irradiation, have been tested ( 1,6,9,14,15). Susceptibility of L. pneumophila to UV-radiation was reported (1,8), but this method is not yet in practical use as a biocidal treatment of cooling tower water, because the quartz glass surface quickly becomes dirty in filthy water and inhibits the penetration of ultraviolet light.…”

mentioning

confidence: 99%

Effects of FLONLIZER®, Ultraviolet Sterilizer, on Legionella Species Inhabiting Cooling Tower Water

Yamamoto

Urakami²,

Nakano³

et al. 1987

Microbiology and Immunology

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Legionella pneumophila in sterile distilled water was not detected after ultraviolet irradiation by FLONLIZER®, a new‐type sterilizer, at a flow rate of 82.5 to 364.8 liters/hr. When irradiated by FLONLIZER® at a flow rate of under 324.0 liters/hr, no viable cells of legionellae, other heterotrophic bacteria and bacterivorous protozoa were detected in the cooling tower water, which was found to contain L. pneumophila. No viable cells of L. pneumophila and L. bozemanii suspended in sterile distilled water were detected after the irradiation with UV‐doses of over 6.16 × 103 μW·sec/cm2. At the irradiation of low UV‐doses under 1.06 × 104 μW·sec/cm2, the viable count of legionellae recuperated by photoreactivation from UV‐damage increased with the exposure time under a white fluorescent lamp. However, in the samples irradiated with UV‐doses of over 3.52 × 104 μW·sec/cm2, equal to the FLONLIZER®, legionellae did not recuperate even after 18 hr illumination with a white fluorescent lamp. FLONLIZER® is thus expected to act as a sterilizer which can control the legionellae inhabiting cooling tower systems placed in outdoor space.

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Photoreactivation of UV-irradiated Legionella pneumophila and other Legionella species

Cited by 64 publications

References 39 publications

UV disinfection of wastewater effluents for unrestricted irrigation

UV disinfection of wastewater effluents for unrestricted irrigation

Reduction of Photoreactivation with the Combined UV/Peracetic Acid Process or by Delayed Exposure to Visible Light

Effects of FLONLIZER®, Ultraviolet Sterilizer, on Legionella Species Inhabiting Cooling Tower Water

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