The photocatalytic disinfection of urban waste waters

Melián, J.A. Herrera; Doña-Rodrı́guez, J.M.; Suárez, Andrés Santiago Suárez; Rendón, E. Tello; Campo, Cecilia Valdés do; Araña, J.; Peña, J. Pérez

doi:10.1016/s0045-6535(99)00502-0

Cited by 158 publications

(52 citation statements)

References 7 publications

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“…This process is based on the ability of a semiconductive catalyst (TiO 2 ) to kill bacteria upon illumination in aqueous solution (1,12,15,16,30). However, the basis for the bactericidal effect of photocatalysis is not well established.…”

mentioning

confidence: 99%

TiO ₂ Photocatalysis Causes DNA Damage via Fenton Reaction-Generated Hydroxyl Radicals during the Recovery Period

Gogniat

Dukan

2007

Appl Environ Microbiol

131

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Here, we show that resistance of Escherichia coli to TiO 2 photocatalysis involves defenses against reactive oxygen species. Results support the idea that TiO 2 photocatalysis generates damage which later becomes deleterious during recovery. We found this to be partly due to DNA attack via hydroxyl radicals generated by the Fenton reaction during recovery.Studies in the past few years have revealed that classical disinfection by chlorine or ozonation can generate carcinogenic and mutagenic by-products, thereby boosting research into alternative methods, such as photocatalysis (2,26,28). This process is based on the ability of a semiconductive catalyst (TiO 2 ) to kill bacteria upon illumination in aqueous solution (1,12,15,16,30). However, the basis for the bactericidal effect of photocatalysis is not well established.Active TiO 2 in anatase crystalline form behaves as a classical semiconductor. The bactericidal effect of photocatalysis with TiO 2 could be due to the presence of reactive oxygen species (ROS), such as superoxide (O 2 · Ϫ ), hydrogen peroxide (H 2 O 2 ), and hydroxyl radical (HO·), generated either by illuminated TiO 2 or by the illumination (mainly UV) of the cells. Most studies have concluded that HO·, directly generated by this process, is the main cause of the bactericidal effect of photocatalysis (5, 19).To prevent the harmful effects of ROS generated during the normal course of aerobic metabolism, especially that of the extremely reactive HO· able to damage DNA (18), bacteria like Escherichia coli are equipped with defenses, including catalases (KatG and KatE) and superoxide dismutases (SodA, SodB, and SodC) (4, 17). These defenses decrease H 2 O 2 and O 2 · Ϫ steady states and consequently limit the formation of HO·, for which no defense exists (22). Previous reports have shown that HO· is generated via a Fenton reaction (H 2 O 2 ϩ Fe 2ϩ 3 HO· ϩ HO Ϫ ϩ Fe 3ϩ ) and that regulating iron uptake by the transcriptional repressor Fur (3, 7) permits maintenance of low-level HO· production.Here, we aimed to investigate the resistance of E. coli to TiO 2 photocatalysis. Cells were grown in Luria-Bertani broth at 37°C on a rotary shaker (160 rpm) to an absorbance at 600 nm of 0.5. We then washed the cells twice with sodium phosphate (0.05 mol/liter, pH 7, 4°C) and resuspended them in sodium phosphate (0.05 mol/liter, pH 7) solution to a concentration of 2 ϫ 10 7 CFU/ml. As previously described (14), culture plates were illuminated from 310 nm to 800 nm with a xenon lamp in a Hanau Suntest system (AM1) at 550 W/m 2 light intensity with a filter cutting off wavelengths below 310 nm. Stopped bacterial growth in the exponential phase followed by incubation in phosphate buffer causes starvation and induction of the RpoS regulon, involved in resistance towards many environmental stresses (7,13). With this in mind, we used a mutant strain of E. coli to test whether the induction of the RpoS regulon protects cells against photocatalysis (Degussa P25, 20% rutile 80% anatase crystalline form; Degussa AG, Switz...

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mentioning

confidence: 99%

TiO ₂ Photocatalysis Causes DNA Damage via Fenton Reaction-Generated Hydroxyl Radicals during the Recovery Period

Gogniat

Dukan

2007

Appl Environ Microbiol

131

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“…[16][17][18][19][20] Recovery of the total coliform and Shigella populations could be explained by the fact that, under oxidative stress, their cells can enter a viable but non cultivable (VBNC) state. 30 UV irradiation and attacks by oxidative species generate changes in the permeability of the lipid membrane and/or modify the bacterial DNA, leading the loss of cultivability while viability remains unaltered.…”

Section: Post Irradiation Events After the Photocatalytic Treatmentmentioning

confidence: 99%

“…[12][13][14] Only a few studies have been published using wastewater. [15][16][17][18][19][20] The effluents studied in this work are from domestic wastewater in the town of Ginebra (Valle del Cauca, Colombia), which was previously treated by various biological treatment systems. Photocatalytic disinfection was studied using two different kinds of light sources: a commercial UV A source (black-light lamp, BLL), and a Hanau Suntest AM-1 solar simulator.…”

Section: Introductionmentioning

confidence: 99%

TiO2 photocatalytic inactivation under simulated solar light of bacterial consortia in domestic wastewaters previously treated by UASB, duckweed and facultative ponds

Rengifo‐Herrera¹,

Pulgarín²,

Machuca³

et al. 2010

Quím. Nova

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Recebido em 28/8/09; aceito em 23/4/09; publicado na web em 9/8/10In this work, TiO 2 photocatalysis was used to disinfect domestic wastewaters previously treated by different biological treatment systems: Upward-flow Anaerobic Sludge Blanket (UASB), facultative pond, and duckweed pond. The microorganisms monitored were E. coli, total coliforms, Shigella species, and Salmonella species. Photocatalytic experiments were carried out using two light sources: a solar simulator (UV intensity: 68-70 W m ). Samples were taken after each treatment stage. Results indicate that bacterial photocatalytic inactivation is affected by characteristics of the effluent, including turbidity, concentration of organic matter, and bacterial concentration, which depend of the type of biological pretreatment previously used.

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“…1993-as publikációjukban [110] arról is beszámolnak, hogy hidroxilgyök-fogó hozzáadásakor nem pusztultak a baktériumok a megvilágított szuszpenzióban. Számos más kutató hangsúlyozza a fotokatalízisben keletkező OH• fontosságát [24,42,100,[115][116][117][118][119][120][121][122], ugyanakkor néhány más gyök, illetve reaktív molekula (mint például a hidrogénperoxid) jelentősége is szóba kerül [24,43,[115][116][117]123].…”

Section: Fertőtlenítés Titán-dioxiddalunclassified

“…Számos publikációt találunk a szakirodalomban, melyben különböző mikroorganizmusok fotokatalitikus inaktiválását vizsgálják: Gram pozitív baktériumok (mint például a Lactobacillus acidophilus [109], az Enterococcus faecalis [37,124], a Streptoccocus faecalis [120], a Bacillus cereus [115], a Bacillus thuringiensis [125], a Micrococcus lylae [100], a Mycobacterium smegmatis [125], vagy a Staphylococcus aureus [24,42,115,124]),…”

Section: Lineáris öSszefüggés a Oh• Koncentráció éS A Fertőtlenítőhatunclassified

Környezeti szennyezők ártalmatlanítása UV- és látható fényre aktív titán-dioxid alapú fotokatalizátorokkal

Veréb¹

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The photocatalytic disinfection of urban waste waters

Cited by 158 publications

References 7 publications

TiO ₂ Photocatalysis Causes DNA Damage via Fenton Reaction-Generated Hydroxyl Radicals during the Recovery Period

TiO ₂ Photocatalysis Causes DNA Damage via Fenton Reaction-Generated Hydroxyl Radicals during the Recovery Period

TiO2 photocatalytic inactivation under simulated solar light of bacterial consortia in domestic wastewaters previously treated by UASB, duckweed and facultative ponds

Környezeti szennyezők ártalmatlanítása UV- és látható fényre aktív titán-dioxid alapú fotokatalizátorokkal

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The photocatalytic disinfection of urban waste waters

Cited by 158 publications

References 7 publications

TiO 2 Photocatalysis Causes DNA Damage via Fenton Reaction-Generated Hydroxyl Radicals during the Recovery Period

TiO 2 Photocatalysis Causes DNA Damage via Fenton Reaction-Generated Hydroxyl Radicals during the Recovery Period

TiO2 photocatalytic inactivation under simulated solar light of bacterial consortia in domestic wastewaters previously treated by UASB, duckweed and facultative ponds

Környezeti szennyezők ártalmatlanítása UV- és látható fényre aktív titán-dioxid alapú fotokatalizátorokkal

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TiO ₂ Photocatalysis Causes DNA Damage via Fenton Reaction-Generated Hydroxyl Radicals during the Recovery Period

TiO ₂ Photocatalysis Causes DNA Damage via Fenton Reaction-Generated Hydroxyl Radicals during the Recovery Period