This study compared three different disinfection processes （chlorination, E-beam, and ozone） and the efficacy of three oxidants （H202, S2O8-, and peroxymonosulfate （MPS）） in removing antibiotic resistant bacter...This study compared three different disinfection processes （chlorination, E-beam, and ozone） and the efficacy of three oxidants （H202, S2O8-, and peroxymonosulfate （MPS）） in removing antibiotic resistant bacteria （ARB） and antibiotic resistance genes （ARGs） in a synthetic wastewater. More than 30 mg/L of chlorine was needed to remove over 90% of ARB and ARG. For the E-beam method, only 1 dose （kGy） was needed to remove ARB and ARG, and ozone could reduce ARB and ARG by more than 90% even at 3 mg/L ozone concentration. In the ozone process, CT values （concentration × time） were compared for ozone alone and combined with different catalysts based on the 2-log removal of ARB and ARG. Ozone treatment yielded a value of 31 and 33 （mg·min）/L for ARB and ARGs respectively. On the other hand, ozone with persulfate yielded 15.9 and 18.5 （mg.min）/L while ozone with monopersulfate yielded a value of 12 and 14.5 （mg·min）/L. This implies that the addition of these catalysts significantly reduces the contact time to achieve a 2-log removal, thus enhancing the process in terms of its kinetics.展开更多
Haloacetamides（HAMs） are cytotoxic, genotoxic, and mutagenic byproducts of drinking water disinfection. They are soft electrophilic compounds that form covalent bonds with the free thiol/thiolate in cysteine residue...Haloacetamides（HAMs） are cytotoxic, genotoxic, and mutagenic byproducts of drinking water disinfection. They are soft electrophilic compounds that form covalent bonds with the free thiol/thiolate in cysteine residues through an S_N2 reaction mechanism.Toxicity of the monohalogenated HAMs（iodoacetamide, IAM; bromoacetamide, BAM;or chloroacetamide, CAM） varied depending on the halogen substituent. The aim of this research was to investigate how the halogen atom affects the reactivity and toxicological properties of HAMs, measured as induction of oxidative/electrophilic stress response and genotoxicity. Additionally, we wanted to determine how well in silico estimates of electrophilic softness matched thiol/thiolate reactivity and in vitro toxicological endpoints.Each of the HAMs significantly induced nuclear Rad51 accumulation and ARE signaling activity compared to a negative control. The rank order of effect was IAM 〉 BAM 〉 CAM for Rad51, and BAM ≈ IAM 〉 CAM for ARE. In general, electrophilic softness and in chemico thiol/thiolate reactivity provided a qualitative indicator of toxicity, as the softer electrophiles IAM and BAM were more thiol/thiolate reactive and were more toxic than CAM.展开更多
基金supported by the Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology (No. 2012-0003505)Korea Ministry of Environment as "Global Top Project" (No. GT-11-B-01-005-1)
文摘This study compared three different disinfection processes （chlorination, E-beam, and ozone） and the efficacy of three oxidants （H202, S2O8-, and peroxymonosulfate （MPS）） in removing antibiotic resistant bacteria （ARB） and antibiotic resistance genes （ARGs） in a synthetic wastewater. More than 30 mg/L of chlorine was needed to remove over 90% of ARB and ARG. For the E-beam method, only 1 dose （kGy） was needed to remove ARB and ARG, and ozone could reduce ARB and ARG by more than 90% even at 3 mg/L ozone concentration. In the ozone process, CT values （concentration × time） were compared for ozone alone and combined with different catalysts based on the 2-log removal of ARB and ARG. Ozone treatment yielded a value of 31 and 33 （mg·min）/L for ARB and ARGs respectively. On the other hand, ozone with persulfate yielded 15.9 and 18.5 （mg.min）/L while ozone with monopersulfate yielded a value of 12 and 14.5 （mg·min）/L. This implies that the addition of these catalysts significantly reduces the contact time to achieve a 2-log removal, thus enhancing the process in terms of its kinetics.
基金partial support from the U.S.Army Engineer Research and Development Center and the Army Environmental Quality Technology program, CESU W9132T-16-2-0005 (MJP)partly supported by the interagency agreement IAG #NTR 12003 from the National Institute of Environmental Health Sciences/Division of the National Toxicology Program to the National Center for Advancing Translational Sciences, National Institutes of Health
文摘Haloacetamides（HAMs） are cytotoxic, genotoxic, and mutagenic byproducts of drinking water disinfection. They are soft electrophilic compounds that form covalent bonds with the free thiol/thiolate in cysteine residues through an S_N2 reaction mechanism.Toxicity of the monohalogenated HAMs（iodoacetamide, IAM; bromoacetamide, BAM;or chloroacetamide, CAM） varied depending on the halogen substituent. The aim of this research was to investigate how the halogen atom affects the reactivity and toxicological properties of HAMs, measured as induction of oxidative/electrophilic stress response and genotoxicity. Additionally, we wanted to determine how well in silico estimates of electrophilic softness matched thiol/thiolate reactivity and in vitro toxicological endpoints.Each of the HAMs significantly induced nuclear Rad51 accumulation and ARE signaling activity compared to a negative control. The rank order of effect was IAM 〉 BAM 〉 CAM for Rad51, and BAM ≈ IAM 〉 CAM for ARE. In general, electrophilic softness and in chemico thiol/thiolate reactivity provided a qualitative indicator of toxicity, as the softer electrophiles IAM and BAM were more thiol/thiolate reactive and were more toxic than CAM.
