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1.
Water Res ; 149: 272-281, 2019 02 01.
Article in English | MEDLINE | ID: mdl-30465985

ABSTRACT

Photo-driven advanced oxidation process (AOP) with peracetic acid (PAA) has been poorly investigated in water and wastewater treatment so far. In the present work its possible use as tertiary treatment of urban wastewater to effectively minimize the release into the environment of contaminants of emerging concern (CECs) and antibiotic-resistant bacteria was investigated. Different initial PAA concentrations, two light sources (sunlight and UV-C) and two different water matrices (groundwater (GW) and wastewater (WW)) were studied. Low PAA doses were found to be effective in the inactivation of antibiotic resistant Escherichia coli (AR E. coli) in GW, with the UV-C process being faster (limit of detection (LOD) achieved for a cumulative energy (QUV) of 0.3 kJL-1 with 0.2 mg PAA L-1) than solar driven one (LOD achieved at QUV = 4.4 kJL-1 with 0.2 mg PAA L-1). Really fast inactivation rates of indigenous AR E. coli were also observed in WW. Higher QUV and PAA initial doses were necessary to effectively remove the three target CECs (carbamazepine (CBZ), diclofenac and sulfamethoxazole), with CBZ being the more refractory one. In conclusion, photo-driven AOP with PAA can be effectively used as tertiary treatment of urban wastewater but initial PAA dose should be optimized to find the best compromise between target bacteria inactivation and CECs removal as well as to prevent scavenging effect of PAA on hydroxyl radicals because of high PAA concentration.


Subject(s)
Wastewater , Water Purification , Disinfection , Drug Resistance, Microbial , Escherichia coli , Peracetic Acid , Sunlight
2.
Sci Rep ; 6: 38145, 2016 12 02.
Article in English | MEDLINE | ID: mdl-27909341

ABSTRACT

Solar water disinfection (SODIS) is a zero-cost intervention measure to disinfect drinking water in areas of poor access to improved water sources, used by more than 6 million people in the world. The bactericidal action of solar radiation in water has been widely proven, nevertheless the causes for this remain still unclear. Scientific literature points out that generation of reactive oxygen species (ROS) inside microorganisms promoted by solar light absorption is the main reason. For the first time, this work reports on the experimental measurement of accumulated intracellular ROS in E. coli during solar irradiation. For this experimental achievement, a modified protocol based on the fluorescent probe dichlorodihydrofluorescein diacetate (DCFH-DA), widely used for oxidative stress in eukaryotic cells, has been tested and validated for E. coli. Our results demonstrate that ROS and their accumulated oxidative damages at intracellular level are key in solar water disinfection.


Subject(s)
Disinfection/methods , Sunlight , Water Microbiology , Water Purification/methods , Water Supply , Escherichia coli K12/metabolism , Escherichia coli K12/radiation effects , Fluoresceins , Fluorescent Dyes , Humans , Reactive Oxygen Species/metabolism , Solar Energy
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