Citation Context

...on of chemical pollutants and inactivation ofsmicroorganisms can be an adequate alternative.sUV-C alone (without H2O2 addition) has been used to a large extent for the oxidationsof several chemicals (=-=Legrini et al., 1993-=-; Tuhkanen, 2004). This process is not usuallysconsidered as an AOP since it is based on the direct photolysis of organic compounds whichsare able to absorb UV-C photons (wavelength of 254 nm). When h...

Citation Context

...talsProtection Agency, 1996). The germicidal effect is based on the absorption of these highenergy UV-C photons by the DNA, inhibiting its replication and consequently thesmicroorganism reproduction (=-=Ravanat et al., 2001-=-). However, these damages can be reversiblesdue to the self-repairing mechanism of the microorganism cells. In contrast, UV-C/H2O2 hassnot been used to such a large extent for disinfection application...

Citation Context

...and Hong, 1999). Since the first work ofsMatsunaga et al. (1985), several publications have been reported for bacteria inactivation withsheterogeneous photocatalysis, showing very successful results (=-=Malato et al., 2009-=-). Thesmechanism of microorganism inactivation is more complex since a significant amount ofshydroxyl radical attacks are required to cause the bacterial lysis, leading to irreversiblesdamages (Malato...

Citation Context

...lso from the stoichiometric equation for total oxidation of each pharmaceutical tosCO2 and H2O). Hydrogen peroxide concentration was followed colorimetrically at 410 nmsafter adding titanium sulfate (=-=Eisenberg, 1943-=-). 3. Results and Discussions3.1. UV-C.sExperiments at low UV-C irradiation power (Figure 1) have shown hardly differencessin irradiation time required to reach a complete E. coli inactivation for dei...

Citation Context

...such as pharmaceuticals in wastewater effluents has taken place. They seem tosbe appropriate for this application as shown by the successful results reported by severalsauthors (Ikehata et al., 2006; =-=Klavarioti et al., 2009-=-). However, very few approaches havesbeen done to their application to disinfection processes which might achieve the simultaneoussinactivation of microorganisms and oxidation of micropollutants (Buff...

Citation Context

...creasing theirsresistance to oxidative stress by increasing the permeability of the membrane to H2O2. Thissabsence of disinfectant effect of H2O2 in SWTP effluents is in agreement with other authorss(=-=Rincón and Pulgarín, 2004-=-; Mamame et al., 2007; Paleologou et al., 2007). Concerning thesoxidation of the pharmaceuticals, no significant effect of H2O2 addition was observed either insthe dark or under UV-A irradiation for b...

Citation Context

...trace level concentrations not only in wastewater treatment plant effluents but alsosin drinking water. Their reported negative effects make it necessary to remove them especiallysfor reuse purposes (=-=Ikehata et al., 2006-=-). Therefore, the use of alternative disinfectionstechnologies for simultaneously removing traces of these emerging micropollutants has to besexplored.sAdvanced Oxidation Processes (AOPs), based on th...

Citation Context

...ver, its addition at high concentrations has also been reported not tosimprove the photocatalytic process since the oxidation of H2O2 by the photogenerated holesslead to a decrease in •OH production (=-=Wang and Hong, 1999-=-). Since the first work ofsMatsunaga et al. (1985), several publications have been reported for bacteria inactivation withsheterogeneous photocatalysis, showing very successful results (Malato et al.,...

Citation Context

...Cl2, and MgSO4) and organic matter (meat peptone, beef extract andsurea) diluted to a total organic carbon value of 15 mg L -1 , similar to effluents of a secondaryswastewater treatment plant (SWTP) (=-=Kositzi et al., 2004-=-).s2.2. Bacterial analysis.sEscherichia coli was selected as model microorganism due to its wide use as faecalscontamination indicator. E. coli K12 strain was provided by the Colección Española desCul...

Citation Context

...09). Once again, although it is expected that the presence of H2O2sfavors the process, there are controversial results in the literature when microrganisms aresinvolved (Hartman and Eisenstark, 1978; =-=Bayliss and Waites, 1980-=-; Lanao et al., 2010).sA notably increase in recent literature regarding these technologies to removesmicropollutants such as pharmaceuticals in wastewater effluents has taken place. They seem tosbe a...

Citation Context

...h its additional production of hydroxyl radicals are alreadysaccepted (Yasar et al., 2007), it remains unclear if the hydrogen peroxide has positive orsnegative effects on the disinfection processes (=-=Labas et al., 2009-=-).sRegarding the oxidation mechanism of TiO2 photocatalysis, it is based on thesactivation of a semiconductor material upon UV-A radiation, eventually producing hydroxylsradicals. The addition of H2O2...

Citation Context

...t, UV-C/H2O2 hassnot been used to such a large extent for disinfection applications. Despite early publicationssconcerning the role of UV-C radiation and H2O2 for inactivation purposes were reporteds(=-=Hartman and Eisenstark, 1978-=-; Sundström et al., 1992), and the disinfectant properties ofshydrogen peroxide together with its additional production of hydroxyl radicals are alreadysaccepted (Yasar et al., 2007), it remains uncle...

Citation Context

...n at 254 nm is lower than that of the other compounds. Therefore, thespharmaceutical structure seems to notably influence the sensitivity to the oxidation process, insagreement with previous reports (=-=Kim et al., 2009-=-). Thus, although the irradiation timesrequired to completely inactivating the bacteria has been really low, it does not guarantee ascomplete photolytic degradation of pharmaceuticals and other possib...

Citation Context

...acterial regrowth (Coohillsand Sagripanti, 2008; Shang et al., 2009) reversing the DNA damages produced uponsabsorption of UV-C photons. And even, inactivation-reactivation curves have been reporteds(=-=Nebot et al., 2007-=-), showing a regrowth phase as function of availability of nutrients and kindsof bacteria.sConcerning the pharmaceuticals, Figure 1 inset shows that their photolytic degradationshas been really slow a...

Citation Context

... increasing the permeability of the membrane to H2O2. Thissabsence of disinfectant effect of H2O2 in SWTP effluents is in agreement with other authorss(Rincón and Pulgarín, 2004; Mamame et al., 2007; =-=Paleologou et al., 2007-=-). Concerning thesoxidation of the pharmaceuticals, no significant effect of H2O2 addition was observed either insthe dark or under UV-A irradiation for both, deionized water and SWTP effluent.sConsum...

Citation Context

...it is expected that the presence of H2O2sfavors the process, there are controversial results in the literature when microrganisms aresinvolved (Hartman and Eisenstark, 1978; Bayliss and Waites, 1980; =-=Lanao et al., 2010-=-).sA notably increase in recent literature regarding these technologies to removesmicropollutants such as pharmaceuticals in wastewater effluents has taken place. They seem tosbe appropriate for this ...

Citation Context

...able bacterial concentration of 3-log after UV-C irradiation and 24 h in dark. Severalsrepairing enzymatic mechanisms have been reported to favor the bacterial regrowth (Coohillsand Sagripanti, 2008; =-=Shang et al., 2009-=-) reversing the DNA damages produced uponsabsorption of UV-C photons. And even, inactivation-reactivation curves have been reporteds(Nebot et al., 2007), showing a regrowth phase as function of availa...

Citation Context

... to such a large extent for disinfection applications. Despite early publicationssconcerning the role of UV-C radiation and H2O2 for inactivation purposes were reporteds(Hartman and Eisenstark, 1978; =-=Sundström et al., 1992-=-), and the disinfectant properties ofshydrogen peroxide together with its additional production of hydroxyl radicals are alreadysaccepted (Yasar et al., 2007), it remains unclear if the hydrogen perox...