To manage potential microbial risks and meet increasingly strict drinking water health standards,UV treatment has attracted increasing attention for use in drinking water systems in China.However,the effects of UV tre...To manage potential microbial risks and meet increasingly strict drinking water health standards,UV treatment has attracted increasing attention for use in drinking water systems in China.However,the effects of UV treatment on microbial control and disinfection byproducts(DBPs)formation in real municipal drinking water systems are poorly understood.Here,we collected water samples from three real drinking water systems in Beijing and Tianjin to investigate the impacts of UV treatment on microbial control and DBP formation.We employed heterotrophic plate count(HPC),flow cytometry(FCM),quantitative PCR analysis,and high-throughput sequencing to measure microorganisms in the samples.Different trends were observed between HPC and total cell count(measured by FCM),indicating that a single indicator could not reflect the real degree of biological re-growth in drinking water distribution systems(DWDSs).A significant increase in the 16S rRNA gene concentration was observed when the UV system was stopped.Besides,the bacterial community composition was similar at the phylum level but differed markedly at the genera level among the three DWDSs.Some chlorine-resistant bacteria,including potential pathogens(e.g.,Acinetobacter)showed a high relative abundance when the UV system was turned off.It can be concluded that UV treatment can mitigate microbial re-growth to some extent.Finally,UV treatment had a limited influence on the formation of DBPs,including trihalomethanes,haloacetic acids,and nitrogenated DBPs.The findings of this study may help to understand the performance of UV treatment in real drinking water systems.展开更多
The efficacy of ultraviolet(UV)disinfection has been validated in numerous studies by using culturebased methods.However,the discovery of viable but non-culturable bacteria has necessitated the investigation of UV dis...The efficacy of ultraviolet(UV)disinfection has been validated in numerous studies by using culturebased methods.However,the discovery of viable but non-culturable bacteria has necessitated the investigation of UV disinfection based on bacterial viability parameters.We used quantitative polymerase chain reaction(qPCR)to investigate DNA damage and evaluated adenosine triphosphate(ATP)to indicate bacterial viability.The results of qPCR effectively showed the DNA damage induced by UV when using longer gene amplicons,in that sufficiently long amplicons of both 16S and gadA indicated that the UV induced DNA damages.The copy concentrations of the long amplicons of 16S and gadA decreased by 2.38 log/mL and 1.88 log/mL,respectively,after exposure to 40 mJ/cm^2 lowpressure UV.After UV exposure,the ATP level in the bacteria did not decrease instantly.Instead it decreased gradually at a rate that was positively related to the UV fluence.For low-pressure UV,this rate of decrease was slow,but for medium pressure UV,this rate of decrease was relatively high when the UV fluence reached 40 mJ/cm^2.At the same UV fluence,the ATP level in the bacteria decreased at a faster rate after exposure to medium-pressure UV.展开更多
Advanced water treatment is commonly used to remove micropollutants such as pesticides,endocrine disrupting chemicals,and disinfection byproducts in modem drinking water treatment plants.However,little attention has b...Advanced water treatment is commonly used to remove micropollutants such as pesticides,endocrine disrupting chemicals,and disinfection byproducts in modem drinking water treatment plants.However,little attention has been paid to the changes in the genotoxicity of substances remaining in the water following the different water treatment processes.In this study,samples were collected from three drinking water treatment plants with different treatment processes.The treated water from each process was analyzed and compared for genotoxicity and the formation of organic compounds.The genotoxicity was evaluated by an umu test,and the acute and chronic toxicity was analyzed through Ecological Structure-Activity Relationship(ECOSAR).The results of the umu test indicated that biological activated carbon reduced the genotoxicity by 38%,77%,and 46%in the three drinking water treatment plants,respectively,while chlorination increased the genotoxicity.Gas chromatograph-mass spectrometry analysis revealed that halogenated hydrocarbons and aromatic compounds were major contributors to genotoxicity.The results of ECOSAR were not consistent with those of the umu test.Therefore,we conclude that genotoxicity cannot be determined using ECOSAR.展开更多
The efficacy of ultraviolet(UV)disinfection has been analyzed and validated by numerous studies using culture-based methods,yet the discovery of the viable but nonculturable state necessitates the investigation of UV ...The efficacy of ultraviolet(UV)disinfection has been analyzed and validated by numerous studies using culture-based methods,yet the discovery of the viable but nonculturable state necessitates the investigation of UV disinfection based on viability parameters.Paired regulators of the SOS response system,recA-lexA,and the programmed cell death system,mazEF,in Escherichia coli were chosen as the target genes,and the effect of UV irradiation on the mRNAs of the four genes was studied.This research showed that,after UV irradiation,the responses of the mRNAs were highly consistent,with reduction percentages of approximately 60% at 20 mJ/cm2,70% at 40 mJ/cm2,and 90% at 80 mJ/cm2,and these reductions were believed to be the result of direct UV damage to nucleic acids.After 24 h of dark incubation,recA and lexA were both upregulated but to a lesser extent for repressor lexA;and mazE and mazF were both downregulated.This result implies that UV irradiation induces the dark repair system more actively,and the cells will proceed to death at a rate similar to that associated with natural decay.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51778323,51761125013 and51290284)the National Science and Technology Major Project of China(Nos.2012ZX07404-002,2017ZX07108-003 and 2017ZX07502-003)
文摘To manage potential microbial risks and meet increasingly strict drinking water health standards,UV treatment has attracted increasing attention for use in drinking water systems in China.However,the effects of UV treatment on microbial control and disinfection byproducts(DBPs)formation in real municipal drinking water systems are poorly understood.Here,we collected water samples from three real drinking water systems in Beijing and Tianjin to investigate the impacts of UV treatment on microbial control and DBP formation.We employed heterotrophic plate count(HPC),flow cytometry(FCM),quantitative PCR analysis,and high-throughput sequencing to measure microorganisms in the samples.Different trends were observed between HPC and total cell count(measured by FCM),indicating that a single indicator could not reflect the real degree of biological re-growth in drinking water distribution systems(DWDSs).A significant increase in the 16S rRNA gene concentration was observed when the UV system was stopped.Besides,the bacterial community composition was similar at the phylum level but differed markedly at the genera level among the three DWDSs.Some chlorine-resistant bacteria,including potential pathogens(e.g.,Acinetobacter)showed a high relative abundance when the UV system was turned off.It can be concluded that UV treatment can mitigate microbial re-growth to some extent.Finally,UV treatment had a limited influence on the formation of DBPs,including trihalomethanes,haloacetic acids,and nitrogenated DBPs.The findings of this study may help to understand the performance of UV treatment in real drinking water systems.
基金This research was supported by the Chinese Major National R&D Project(Nos.2017ZX07108-003 and 2017ZX07502003).
文摘The efficacy of ultraviolet(UV)disinfection has been validated in numerous studies by using culturebased methods.However,the discovery of viable but non-culturable bacteria has necessitated the investigation of UV disinfection based on bacterial viability parameters.We used quantitative polymerase chain reaction(qPCR)to investigate DNA damage and evaluated adenosine triphosphate(ATP)to indicate bacterial viability.The results of qPCR effectively showed the DNA damage induced by UV when using longer gene amplicons,in that sufficiently long amplicons of both 16S and gadA indicated that the UV induced DNA damages.The copy concentrations of the long amplicons of 16S and gadA decreased by 2.38 log/mL and 1.88 log/mL,respectively,after exposure to 40 mJ/cm^2 lowpressure UV.After UV exposure,the ATP level in the bacteria did not decrease instantly.Instead it decreased gradually at a rate that was positively related to the UV fluence.For low-pressure UV,this rate of decrease was slow,but for medium pressure UV,this rate of decrease was relatively high when the UV fluence reached 40 mJ/cm^2.At the same UV fluence,the ATP level in the bacteria decreased at a faster rate after exposure to medium-pressure UV.
基金supported by the National Natural Science Foundation of China(Grant Nos.51778323,51761125013 and 51290284)the National Science and Technology Major Project of China(Grant Nos.2012ZX07404-002,2017ZX07108-003 and 2017ZX07502003).
文摘Advanced water treatment is commonly used to remove micropollutants such as pesticides,endocrine disrupting chemicals,and disinfection byproducts in modem drinking water treatment plants.However,little attention has been paid to the changes in the genotoxicity of substances remaining in the water following the different water treatment processes.In this study,samples were collected from three drinking water treatment plants with different treatment processes.The treated water from each process was analyzed and compared for genotoxicity and the formation of organic compounds.The genotoxicity was evaluated by an umu test,and the acute and chronic toxicity was analyzed through Ecological Structure-Activity Relationship(ECOSAR).The results of the umu test indicated that biological activated carbon reduced the genotoxicity by 38%,77%,and 46%in the three drinking water treatment plants,respectively,while chlorination increased the genotoxicity.Gas chromatograph-mass spectrometry analysis revealed that halogenated hydrocarbons and aromatic compounds were major contributors to genotoxicity.The results of ECOSAR were not consistent with those of the umu test.Therefore,we conclude that genotoxicity cannot be determined using ECOSAR.
文摘The efficacy of ultraviolet(UV)disinfection has been analyzed and validated by numerous studies using culture-based methods,yet the discovery of the viable but nonculturable state necessitates the investigation of UV disinfection based on viability parameters.Paired regulators of the SOS response system,recA-lexA,and the programmed cell death system,mazEF,in Escherichia coli were chosen as the target genes,and the effect of UV irradiation on the mRNAs of the four genes was studied.This research showed that,after UV irradiation,the responses of the mRNAs were highly consistent,with reduction percentages of approximately 60% at 20 mJ/cm2,70% at 40 mJ/cm2,and 90% at 80 mJ/cm2,and these reductions were believed to be the result of direct UV damage to nucleic acids.After 24 h of dark incubation,recA and lexA were both upregulated but to a lesser extent for repressor lexA;and mazE and mazF were both downregulated.This result implies that UV irradiation induces the dark repair system more actively,and the cells will proceed to death at a rate similar to that associated with natural decay.
