The effects of disinfection efficiency on microbial communities and the corrosion of cast iron pipes in drinking water distribution systems(DWDSs)were studied.Two annular reactors(ARs)that simulated actual running con...The effects of disinfection efficiency on microbial communities and the corrosion of cast iron pipes in drinking water distribution systems(DWDSs)were studied.Two annular reactors(ARs)that simulated actual running conditions with UV/Cl2 disinfection and chlorination alone were used.High chlorine consumption and corrosion rate were found in the AR with UV/Cl2.According to functional genes and pyrosequencing tests,a high percentage of iron recycling bacteria was detected within the biofilm of the AR with Cl2 at early running stage,whereas siderophore-producing bacteria were dominant in the biofilm of the AR with UV/Cl2.At the early running stage,the sequential use of UV light and an initial high chlorine dosage suppressed the biomass and iron-recycling bacteria in both bulk water and biofilms,thereby forming less protective scales against further corrosion,which enhanced chlorine consumption.Non-metric multidimensional scaling analysis showed that the bacterial communities in the ARs shaped from within rather than being imported by influents.These results indicate that the initial high disinfection efficiency within the distribution system had not contributed to the accumulation of iron-recycling bacteria at the early running stages.This study offer certain implications for controlling corrosion and water quality in DWDSs.展开更多
Concerns have been raised about both the disinfection and the reusability of respiratory protective equipment following a disinfection process.Currently,there is little data available on the effects of disinfection an...Concerns have been raised about both the disinfection and the reusability of respiratory protective equipment following a disinfection process.Currently,there is little data available on the effects of disinfection and decontamination on positive pressure respiratory protective hoods(PPRPH).In this study,we evaluated the effect of vaporized hydrogen peroxide(VHP)on the disinfection of PPRPH to determine applicability of this method for disinfection of protective equipment,especially protective equipment with an electric supply system.A hydrogen peroxide-based fumigation sterilization cabinet was developed particularly for disinfection of protective equipment,and the disinfection experiments were conducted using four PPRPHs hung in the fumigation chamber.The pathogenic microorganism Geobacillus stearothermophilus ATCC 7953 was used as a biological indicator in this study and the relationship between air flow(the amount of VHP)and disinfection was investigated.Both function and the material physical properties of the PPRPH were assessed following the disinfection procedure.No surviving Geobacillus stearothermophilus ATCC 7953,both inside and outside of these disinfected PPRPHs,could be observed after a 60 min treatment with an air flow of 10.5–12.3 m^(3)/h.Both function and material physical properties of these PPRPHs met the working requirements after disinfection.This study indicates that air flow in the fumigation chamber directly influences the concentration of VHP.The protective equipment fumigation sterilization cabinet developed in this paper achieves the complete sterilization of the PPRPHs when the air flow is at 10.5–12.3 m^(3)/h,and provides a potential solution for the disinfection of various kind of protective equipment.展开更多
基金supported by the National Natural Science Foundation of China(Nos.31771726,51708372)the project of Agriculture Research System of China(No.CARS-18).
文摘The effects of disinfection efficiency on microbial communities and the corrosion of cast iron pipes in drinking water distribution systems(DWDSs)were studied.Two annular reactors(ARs)that simulated actual running conditions with UV/Cl2 disinfection and chlorination alone were used.High chlorine consumption and corrosion rate were found in the AR with UV/Cl2.According to functional genes and pyrosequencing tests,a high percentage of iron recycling bacteria was detected within the biofilm of the AR with Cl2 at early running stage,whereas siderophore-producing bacteria were dominant in the biofilm of the AR with UV/Cl2.At the early running stage,the sequential use of UV light and an initial high chlorine dosage suppressed the biomass and iron-recycling bacteria in both bulk water and biofilms,thereby forming less protective scales against further corrosion,which enhanced chlorine consumption.Non-metric multidimensional scaling analysis showed that the bacterial communities in the ARs shaped from within rather than being imported by influents.These results indicate that the initial high disinfection efficiency within the distribution system had not contributed to the accumulation of iron-recycling bacteria at the early running stages.This study offer certain implications for controlling corrosion and water quality in DWDSs.
基金funding projects of Chinese Ministry of Science and Technology:National Key research and development plan of China(2016YFC1201404)the Megaproject for Infectious Disease Research of China(2017ZX10304403-004-001).
文摘Concerns have been raised about both the disinfection and the reusability of respiratory protective equipment following a disinfection process.Currently,there is little data available on the effects of disinfection and decontamination on positive pressure respiratory protective hoods(PPRPH).In this study,we evaluated the effect of vaporized hydrogen peroxide(VHP)on the disinfection of PPRPH to determine applicability of this method for disinfection of protective equipment,especially protective equipment with an electric supply system.A hydrogen peroxide-based fumigation sterilization cabinet was developed particularly for disinfection of protective equipment,and the disinfection experiments were conducted using four PPRPHs hung in the fumigation chamber.The pathogenic microorganism Geobacillus stearothermophilus ATCC 7953 was used as a biological indicator in this study and the relationship between air flow(the amount of VHP)and disinfection was investigated.Both function and the material physical properties of the PPRPH were assessed following the disinfection procedure.No surviving Geobacillus stearothermophilus ATCC 7953,both inside and outside of these disinfected PPRPHs,could be observed after a 60 min treatment with an air flow of 10.5–12.3 m^(3)/h.Both function and material physical properties of these PPRPHs met the working requirements after disinfection.This study indicates that air flow in the fumigation chamber directly influences the concentration of VHP.The protective equipment fumigation sterilization cabinet developed in this paper achieves the complete sterilization of the PPRPHs when the air flow is at 10.5–12.3 m^(3)/h,and provides a potential solution for the disinfection of various kind of protective equipment.
