The high-active bacteria were screened from 8 dominant bacteria obtained from the natural water body,and then the bioaugmentation activated carbon was formed by hydraulic immobilization of the high-active bacteria. Pl...The high-active bacteria were screened from 8 dominant bacteria obtained from the natural water body,and then the bioaugmentation activated carbon was formed by hydraulic immobilization of the high-active bacteria. Plant-scale studies on removal characteristics of disinfection by-products formation potentials (DBPFP) by bioaugmentation activated carbon process were conducted for micro-polluted raw water treatment. The results show that the bioaugmentation activated carbon process has adopted better purification efficiency to THMFP and HAAFP than traditional biological activated carbon process,and that average removal efficiencies of THMFP and HAAFP can reach 35% and 39.7% during the test period,increasing by more than 10% compared with traditional biological activated carbon process. The removal efficiencies of THMFP and HAAFP are stable because of the biodegradation of the high-active bacteria and the adsorption of active carbon. The biodegradability of CHCl3 formation potential is better as compared with that of CHCl2Br and CHClBr2 formation potentials among THMFP,and high removal efficiency of CHCl3formation potential is obtained by bioaugmentation degradation of the high-active bacteria. The biodegradability of HAAFP is better in comparison with that of THMFP,and the chemical properties of HAAFP are propitious to adsorption of activated carbon. Thus,HAAFP is on predominance during the competitive removal process with THMFP.展开更多
Objective To introduce a new sequential chlorination disinfection process in which short-term free chlorine and chloramine are sequentially added. Methods Pilot tests of this sequential chlorination were carried out i...Objective To introduce a new sequential chlorination disinfection process in which short-term free chlorine and chloramine are sequentially added. Methods Pilot tests of this sequential chlorination were carried out in a drinking water plant. Results The sequential chlorination disinfection process had the same or better efficiency on microbe(including virus) inactivation compared with the free chlorine disinfection process. There seemed to be some synergetic disinfection effect between free chlorine and monochloramine because they attacked different targets. The sequential chlorination disinfection process resulted in 35.7%-77.0% TTHM formation and 36.6%-54.8% THAA5 formation less than the free chlorination process. The poorer the water quality was,the more advantage the sequential chlorination disinfection had over the free chlorination. Conclusion This process takes advantages of free chlorine's quick inactivation of microorganisms and chloramine's low disinfection by-product(DBP) yield and long-term residual effect,allowing simultaneous control of microbes and DBPs in an effective and economic way.展开更多
Dissolved organic matter(DOM) has been identified as precursor for disinfection by-products(DBPs) formation during chlorination. Recently,it has been demonstrated that the characteristics of DOM influence the DBPs for...Dissolved organic matter(DOM) has been identified as precursor for disinfection by-products(DBPs) formation during chlorination. Recently,it has been demonstrated that the characteristics of DOM influence the DBPs formation mechanism. A study was,therefore,initiated to investigate the effects of DOM fractions on DBPs formation mechanism. In the chlorination process,organic acids are dominant precursors of total thihalomethanes(TTHM) because of the νC-O and unsaturated structures. Furthermore,the TTHM formation of organic acids was affected by pH more greatly. Based on the fluorescence spectroscopy analysis,DOM fractions contained several fluorescence substances. During chlorination,humic acid-like substances were found to exhibit high chlorine reactivity and hydrophobic organics decomposed to smaller molecules faster than hydrophilic organics even at lower chlorine dosages. Unlike hydrophobic fractions,hydrophilic organics showed no toxicity following chlorination,suggesting that the toxic structures in hydrophilic organics showed high chlorine reactivity during chlorination.展开更多
The removal of disinfection by-products formation potential(DBPFP) in artificially intensified biological activated carbon(IBAC) process which is developed on the basis of traditional ozone granular activated carbon w...The removal of disinfection by-products formation potential(DBPFP) in artificially intensified biological activated carbon(IBAC) process which is developed on the basis of traditional ozone granular activated carbon was evaluated. By IBAC removals of 31% and 68% for THMFP and HAAFP were obtained respectively. Under identical conditions, the removals of the same substances were 4% and 32% respectively only by the granular activated carbon(GAC) process. Compared with GAC, the high removal rates of the two formed potential substances were due to the increasing of bioactivity of the media and the synergistic capabilities of biological degradation cooperating with activated carbon adsorption of organic compounds. A clear linear correlation(R 2=0.9562 and R 2=0.9007) between DOC HAAFP removal rate and Empty Bed Contact Time(EBCT) of IBAC process was observed, while that between THMFP removal rate and EBCT of GAC was R 2=0.9782. In addition certain linear correlations between THMFP, HAAFP and UV 254 (R 2=0.855 and R 2=0.7702) were found for the treated water. For IBAC process there are also more advantages such as long backwashing cycle time, low backwashing intensity and prolonging activated carbon lifetime and so on.展开更多
Gravity-driven membrane(GDM)systems have been well developed previously;however,impacts of driving(i.e.,transmembrane)pressure on their performance received little attention,which may infuence GDM performance.In this ...Gravity-driven membrane(GDM)systems have been well developed previously;however,impacts of driving(i.e.,transmembrane)pressure on their performance received little attention,which may infuence GDM performance.In this study,we evaluated 4 GDM systems via altering the transmembrane pressure from 50 mbar to 150 mbar with 2 groups,treating surface water in Beijing,China.Results showed that less driving pressure was more favorable.Specifically,compared to groups(150 mbar),groups under a pressure of 50 mbar were found to have greater normalized permeability and lower total resistance.During the whole operation period,the quality of effuents was gradually improved.For example,the removal efficiency of UV254was significantly improved;particularly,under low driving pressure,the removal efficiency of UV254in PES GDM system increased by 11.91%,as compared to the corresponding system under high driving pressure.This observation was consistent with the reduction on disinfection by-products(DBPs)formation potential;groups under 50 mbar achieved better DBPs potential control,indicating the advantages of lower driving pressure.Biofilms were analyzed and responsible for these differences,and distinct distributions of bacteria communities of two GDM systems under 50 and 150 mbar may be responsible for various humic-like substances removal efficiency.Overall,GDM systems under less pressure should be considered and expected to provide suggestions on the design of GDM systems in real applications.展开更多
Permanganate/sulfite(Mn(VII)/S(IV))process is a promising pre-oxidation technology for sequestering the emerging organic contaminants in drinking water treatment plant.Iopamidol(IPM),a representative of iodinated X-ra...Permanganate/sulfite(Mn(VII)/S(IV))process is a promising pre-oxidation technology for sequestering the emerging organic contaminants in drinking water treatment plant.Iopamidol(IPM),a representative of iodinated X-ray contrast media,has been widely detected in water sources and has the risk of forming iodinated disinfection byproducts(I-DBPs)in water treatment system.In this study,we investigated the evolution of iodine species during the IPM degradation by the Mn(VII)/S(IV)process and its effect on the subsequent formation of I-DBPs during chlorination at pH 7.0 and 8.0.IPM could be effectively degraded in the Mn(VII)/S(IV)process at environmentally relevant pH(pH 7.0 and 8.0).The results of quenching and competitive oxidation kinetic experiments revealed that SO^(·-)_(4)was the major reactive oxidizing species contributing to the degradation of IPM whereas the contributions of HO·and reactive manganese species were negligible in the Mn(VII)/S(IV)process.I–and IO–3were generated while no HOI was detected during the degradation of IPM in the Mn(VII)/S(IV)process.The effects of IPM oxidation by Mn(VII)/S(IV)on the subsequent formation of chlorinated disinfection by-products(Cl-DBPs)during chlorination were related to the category of Cl-DBPs.The pre-oxidation of IPM by Mn(VII)/S(IV)resulted in the generation of I-DBPs during the disinfection process although no I-DBPs were detected if no pre-oxidation was applied.The finding of this study suggested that attention should be paid to the toxicity of DBPs when water containing iodinated organic contaminants is treated by Mn(VII)/S(IV)process or other pre-oxidation technologies.展开更多
Identification and characterization of disinfection by-product(DBP)precursors could help optimize drinkingwater treatment processes and improve the quality of finishedwater.This study comprehensively investigated the ...Identification and characterization of disinfection by-product(DBP)precursors could help optimize drinkingwater treatment processes and improve the quality of finishedwater.This study comprehensively investigated the characteristics of dissolved organic matter(DOM),the hydrophilicity and molecule weight(MW)of DBP precursor and DBP-associated toxicity along the typical full-scale treatment processes.The results showed that dissolved organic carbon and dissolved organic nitrogen content,the fluorescence intensity and the SUVA254 value in raw water significantly decreased after the whole treatment processes.Conventional treatment processes were in favor of the removal of high-MW and hydrophobic DOM,which are important precursors of trihalomethane and haloacetic acid.Compared with conventional treatment processes,Ozone integrated with biological activated carbon(O3-BAC)processes enhanced the removal efficiencies of DOM with different MW and hydrophobic fractions,leading to a further decrease in almost all DBP formation potential and DBP-associated toxicity.However,almost 50%of the detected DBP precursors in raw water has not been removed after the coagulation-sedimentation-filtration integrated with O3-BAC advanced treatment processes.These remaining precursors were found to be mainly hydrophilic and low-MW(<1.0 kDa)organics.Moreover,they would largely contribute to the formation of haloacetaldehydes and haloacetonitriles,which dominated the calculated cytotoxicity.Since current drinking water treatment process could not effectively control the highly toxic DBPs,the removal of hydrophilic and low-MW organics in drinking water treatment plants should be focused on in the future.展开更多
Sulfate radicals have been increasingly used for the pathogen inactivation due to their strong redox ability and high selectivity for electron-rich species in the last decade.The application of sulfate radicals in wat...Sulfate radicals have been increasingly used for the pathogen inactivation due to their strong redox ability and high selectivity for electron-rich species in the last decade.The application of sulfate radicals in water disinfection has become a very promising technology.However,there is currently a lack of reviews of sulfate radicals inactivated pathogenic microorganisms.At the same time,less attention has been paid to disinfection by-products produced by the use of sulfate radicals to inactivate microorganisms.This paper begins with a brief overview of sulfate radicals’properties.Then,the progress in water disinfection by sulfate radicals is summarized.The mechanism and inactivation kinetics of inactivating microorganisms are briefly described.After that,the disinfection by-products produced by reactions of sulfate radicals with chlorine,bromine,iodide ions and organic halogens in water are also discussed.In response to these possible challenges,this article concludes with some specific solutions and future research directions.展开更多
Haloacetaldehydes(HALs)are the third largest disinfection by-products(DBPs)class by mass in drinking water.Most of them alone in high doses are more cytotoxic and genotoxic than regulated DBPs.However,the toxic effect...Haloacetaldehydes(HALs)are the third largest disinfection by-products(DBPs)class by mass in drinking water.Most of them alone in high doses are more cytotoxic and genotoxic than regulated DBPs.However,the toxic effects of mixed exposure to HALs at environmentally relevant levels are still unknown.Given that genotoxicity is critical for risk assessment,we employed multiple genotoxic tests including the Salmonella typhimurium revertant mutation assay(Ames assay),the single cell gel electrophoresis(SCGE)assay,the cytoplasmic blocking micronucleus(CBMN)assay,and theγ-H2AX assay to investigate the genotoxicity of HALs based on the HALs concentrations and components detected in the finished drinking water of Shanghai,China.The results demonstrated the concentrations of HALs were low,ranging from 0.04µg/L to 4.47µg/L,and the total concentration was 10.85µg/L.Although the mutagenicity of HALs was negative even at 1000-fold concentrations in the real world,mixed exposure to 100 and 1000-fold concentrations HALs resulted in DNA and chromosomal damage in human hepotocyte(HepG2)cells.HALs significantly increased the levels of reactive oxygen species(ROS)andγ-H2AX and activated nuclear factor erythroid-derived factor 2-related factor 2(NRF2)pathway-related protein expressions in HepG2 cells.The antioxidant NAC could ameliorate NRF2 pathway-related protein expression and DNA damage caused by HALs,suggesting that the genotoxicity of mixed exposure to HALs involved cellular oxidative stress and NRF2 pathway activation.展开更多
The UV irradiation is used for removing Antibiotic Resistant Bacteria(ARB)and Antibiotic Resistance Genes(ARG)from wastewater treatment.Bacteriophages are viruses that infect within bacteria,are recognized for bacteri...The UV irradiation is used for removing Antibiotic Resistant Bacteria(ARB)and Antibiotic Resistance Genes(ARG)from wastewater treatment.Bacteriophages are viruses that infect within bacteria,are recognized for bacterial control.The influence of some parameters in quantification and performance influencing of pathogen demobilization could be considered in disinfection of wastewater.The comparison of Polyvalent phage(NE1)versus Coliphage(NE4)in suppressing a bacterium Escherichia coli(NDM-1:b-lactam-resistant)with UV irradiation was observed the efficacy in reduction of cells in the disinfection and parameter process.The results with the effect of UV-C irradiation on NDM-1 infected with 1%of NE4 showed a decrease of cells from 8×10^(6)to 2×10^(5)in 60 min with UV-C dose.The NDM1(E.coli)was infected with 1%of NE4(Polyvalent Phage)under magnetic stirring for 1 h,the cells count was 8×10^(6).After 1 h in UV-C e×posure,the cells number reached 3×10^(5).The NDM1 that was e×posed in 1 h of UV-C irradiation and then was infected with 1%of NE4.Cells counting were done 24 h after this procedure.These cells were e×posed in UV-C and showed a reduction in the number of cells from 1×10^(8)to 4×10^(5)after 60 min.The results indicate that bacteriophages can mitigate bacteria species,and combined the conventional water disinfection technologies that can support the microbial safety control strategies.展开更多
Objective:To evaluate the application value of a refined quality control management model for a sterilization supply center.Methods:A retrospective analysis was conducted on the work situation of the sterilization sup...Objective:To evaluate the application value of a refined quality control management model for a sterilization supply center.Methods:A retrospective analysis was conducted on the work situation of the sterilization supply center from January 2021 to January 2023.The work situation before January 31,2022,was classified as the control group;a routine quality control management model was implemented,and the work situation after January 31,2022,was classified as the observation group.The quality of medical device management and department satisfaction between the two groups were compared.Results:The timely recovery and supply rate,classification and cleaning pass rate,disinfection pass rate,packaging pass rate,sterilization pass rate,and department satisfaction score in the observation group were all higher than those of the control group(P<0.05).Conclusion:Implementing a refined quality control management model in the sterilization supply center can improve the quality management level of medical devices and department satisfaction and is worthy of promotion.展开更多
Dissolved black carbon(DBC)released from biochar can be one of the potential disinfection by-products(DBPs)precursors in the dissolved organic matter pool.However,the physiochemical and structural properties of DBC an...Dissolved black carbon(DBC)released from biochar can be one of the potential disinfection by-products(DBPs)precursors in the dissolved organic matter pool.However,the physiochemical and structural properties of DBC and the effects on the development of DBPs and DBP formation potential(DBPFP)during the disinfection process remain unclear.In this study,the characteristics of two kinds of DBC,namely,animal-derived DBC(poultry litter DBC,PL-DBC)and plant-derived DBC(wheat straw DBC,WS-DBC),were investigated.The effects of different kinds of DBC on the evolution of DBPs and DBPFP in chlorine and chloramine disinfection processes were compared with natural organic matter(NOM).The results showed that the total DBPs concentrations derived from PL-DBC,WS-DBC and NOM were similar during chlorination(i.e.,61.23µg/L,64.59µg/L and 64.66µg/L,respectively)and chloramination(i.e.,44.63µg/L,44.42µg/L and 45.58µg/L,respectively).The lower total DBPs and DBPFP concentrations in chloramination could be attributed to the fact that the introduction of ammonia in chloramine inhibited the breaking of the bond between the disinfectant and the active group of the precursor.Additionally,DBC presented much lower total DBPFP concentrations than NOM in both chlorination and chloramination.However,both kinds of DBC tended to form more monochloroacetic acids and haloacetamides than NOM,which could result from the higher organic strength,higher protein matter,and nitrogen-rich soluble microbial products of DBC.展开更多
Disinfection by-products(DBPs) formed during water disinfection has drawn significant public concern due to its toxicity. Since the first discovery of the trihalomethanes in 1974,continued effort has been devoted on D...Disinfection by-products(DBPs) formed during water disinfection has drawn significant public concern due to its toxicity. Since the first discovery of the trihalomethanes in 1974,continued effort has been devoted on DBPs worldwide to investigate the formation mechanism, levels, toxicity and control measures in drinking water. This review summarizes the main achievements on DBP research in China, which included:(1) the investigation of known DBP occurrence in drinking water of China;(2) the enhanced removal of DBP precursor by water treatment process;(3) the disinfection optimization to minimize DBP formation;and(4) the identification of unknown DBPs in drinking water. Although the research of DBPs in China cover the whole formation process of DBPs, there is still a challenge in effectively controlling the drinking water quality risk induced by DBPs, an integrated research framework including chemistry, toxicology, engineering, and epidemiology is especially crucial.展开更多
Disinfection by-products(DBPs), formed from the reactions of disinfectants with natural organic matter and halides in drinking water, were considered to be cytotoxic and genotoxic, and might trigger various cancers. T...Disinfection by-products(DBPs), formed from the reactions of disinfectants with natural organic matter and halides in drinking water, were considered to be cytotoxic and genotoxic, and might trigger various cancers. The relatively low concentration of DBPs in finished water(low μg/L or even ng/L levels) and the interference from water matrix inhibited in situ determination of DBPs. Moreover, the further formation and degradation of DBPs by disinfectants during the holding time(several hours to several days) from sample collection to analysis could adversely affect the determination of DBPs. To obtain accurate, precise and reliable data of DBP occurrence and formation, robust and reliable sample preservation is indispensable. However, the commonly used quenching agents(e.g., sodium sulfite, sodium thiosulfate, and ascorbic acid) for sample preservation can decompose reactive DBPs by reductive dehalogenation. This study evaluated the performance of N-acetylcysteine(NAC) and glutathione(GSH) as quenching agents for the analysis of halogenated DBPs by investigating the stoichiometry of the disinfectant-quenching agent reaction, the formation of DBPs during chlor(am)ination of NAC or GSH, and the effects of NAC or GSH on the stability of 18 individual DBPs and total organic halogen(TOX). Based on the results of this study, NAC and GSH were considered to be ideal quenching agents for the analysis of most DBPs and TOX, except halonitromethanes.展开更多
Disinfection is an indispensable water treatment process for killing harmful pathogens and protecting human health. However, the disinfection has caused significant public concern due to the formation of toxic disinfe...Disinfection is an indispensable water treatment process for killing harmful pathogens and protecting human health. However, the disinfection has caused significant public concern due to the formation of toxic disinfection by-products(DBPs). Lots of studies on disinfection and DBPs have been performed in the world since 1974. Although related studies in China started in1980 s, a great progress has been achieved during the last three decades. Therefore, this review summarized the main achievements on disinfection and DPBs studies in China, which included:(1) the occurrence of DBPs in water of China,(2) the identification and detection methods of DBPs,(3) the formation mechanisms of DBPs during disinfection process,(4) the toxicological effects and epidemiological surveys of DBPs,(5) the control and management countermeasures of DBPs in water disinfection, and(6) the challenges and chances of DBPs studies in future. It is expected that this review would provide useful information and reference for optimizing disinfection process, reducing DBPs formation and protecting human health.展开更多
Background: Laboratory personnel is at risk of biological contamination leading to laboratory-acquired infections (LAIs). The use of disinfection products is essential in the prevention of these infections. This work ...Background: Laboratory personnel is at risk of biological contamination leading to laboratory-acquired infections (LAIs). The use of disinfection products is essential in the prevention of these infections. This work aimed to evaluate the effectiveness of antimicrobial agents used in disinfection in bacteriology laboratories in Togo. Methods: This was a cross-sectional study conducted from June to December 2021 in all bacteriology laboratories in Togo. Swabs taken before and after disinfection of surfaces and staff hands were immediately plated on agar media. Counting and identification of isolated colonies were done after 24 hours of incubation. The ANOVA test was used to compare calculated means, prevalence ratio (PR) and 95% confidence intervals (CI) to compare bacterial frequencies. Results: A total of 393 samples were taken, of which 41.2% were from hands. Before disinfection, surfaces were more contaminated than hands with respectively 40.4% and 29.6% (PR = 1.3;CI 95% = [0.9 - 1.9]). After surface disinfection with 0.5% of chlorine solution, bacterial elimination was total, but partial on hands washed with soap, with residual contamination of 3.7%. A total of 108 strains were isolated before disinfection of which Klebsiella spp. 38.9% and Staphylococcus spp. 25.0%;after disinfection 4 strains were isolated of which: Staphylococcus spp. 75.0% and Klebsiella spp. 25.0%. Conclusion: Surface disinfection was more effective than hand washing with soap and water. We recommend proper hand washing.展开更多
It is necessary to treat pathogen-infected water before its utilisation.Of conventionally used treatment methods,solar photocatalysis has gained considerable momentum owing to its operational simplicity and capacity t...It is necessary to treat pathogen-infected water before its utilisation.Of conventionally used treatment methods,solar photocatalysis has gained considerable momentum owing to its operational simplicity and capacity to use freely and abundantly available solar energy.This article systematically reviewed the disinfection of water with photocatalysis.It addressed the concerns of microbial infection of water and the fundamentals behind its treatment with photocatalysis.It presented an in-depth description of pathogenic deactivation with powerful reactive oxygen species.Special emphasis was given to process intensification as it is an attractive technique that provides multifunctionality and/or equipment miniaturisation.Solar reactor design regarding mobilised/immobilised photocatalysts and compound parabolic concentrators were elucidated.Finally,key parameters governing photoperformance,corresponding trade-offs,and the need for their optimisation were discussed.Overall,this article is a single point of reference for researchers,environmentalists,and industrialists who address the ever-severing challenge of providing clean water whilst also maintaining energy sustainability.展开更多
Disinfection of water for human use is essential to protect against microbial disease;however, disinfection also leads to formation of disinfection by-products(DBPs), some of which are of health concern. From a chemic...Disinfection of water for human use is essential to protect against microbial disease;however, disinfection also leads to formation of disinfection by-products(DBPs), some of which are of health concern. From a chemical perspective, swimming pools are a complex matrix, with continual addition of a wide range of natural and anthropogenic chemicals via filling waters, disinfectant addition, pharmaceuticals and personal care products and human body excretions. Natural organic matter, trace amounts of DBPs and chlorine or chloramines may be introduced by the filling water, which is commonly disinfected distributed drinking water. Chlorine and/or bromine is continually introduced via the addition of chemical disinfectants to the pool. Human body excretions(sweat, urine and saliva) and pharmaceuticals and personal care products(sunscreens, cosmetics, hair products and lotions) are introduced by swimmers. High addition of disinfectant leads to a high formation of DBPs from reaction of some of the chemicals with the disinfectant.Swimming pool air is also of concern as volatile DBPs partition into the air above the pool.The presence of bromine leads to the formation of a wide range of bromo-and bromo/chloro-DBPs, and Br-DBPs are more toxic than their chlorinated analogues. This is particularly important for seawater-filled pools or pools using a bromine-based disinfectant.This review summarises chemical contaminants and DBPs in swimming pool waters, as well as in the air above pools. Factors that have been found to affect DBP formation in pools are discussed. The impact of the swimming pool environment on human health is reviewed.展开更多
The potential role of personal items in the transmission of pathogens is poorly understood. In this study, we cultured bacteria of public health importance found on wristbands, determined whether there is a correlatio...The potential role of personal items in the transmission of pathogens is poorly understood. In this study, we cultured bacteria of public health importance found on wristbands, determined whether there is a correlation between wristband material and prevalence, and tested three household disinfectants for efficacy in reducing bacteria on wristbands made of plastic, rubber, metal, and cloth, using standard microbiological assays. Total cultivable bacteria, Staphylococci, Enterobacteria (Escherichia coli), and Pseudomonas on 20 smartwatch wristbands were cultured from randomly recruited subjects. Nearly all wristbands (95%) were contaminated, with the highest average numbers of 3.46E+4 cfu/cm<sup>2</sup> and 1.52E+4 cfu/cm<sup>2</sup> on rubber and plastic bands respectively. Metallic gold and silver wristbands had zero to 18 cfu/cm<sup>2</sup>. While the high prevalence of Staphylococcus spp (85% of wristbands)—skin microbiota;was not unexpected, the occurrence of Pseudomonas spp (30%), and enteric bacteria (60%), even at relatively low numbers is of public health significance. Bacterial load on individual subjects varied remarkably with males and females harboring average total bacteria of 4.045 and 3.42 log<sub>10</sub>cfu/cm<sup>2</sup> of wristband, respectively. The most important predictor of wristband bacteria load was the texture of wristband material and activity (hygiene) of the subject at sampling time. Potential pathogens—Staphylococcus aureus (8143 cfu/cm<sup>2</sup>) and Pseudomonas spp. (1126 cfu/cm<sup>2</sup>) were most abundant on cloth and rubber wristbands, respectively, while the presence of the E. coli group was associated with animal handling activity by a veterinarian. Lysol Disinfectant Spray and 70% Ethanol were highly effective regardless of wristband material with >99.99% kill rate and a log cfu/cm<sup>2</sup> reduction of 3 - 4.0 and 3 - 4.5 respectively within 30 seconds. Apple Cider Vinegar (ACV) was not as potent. Only 2 - 3.5 log cfu/cm<sup>2</sup> drop was obtained after 120 seconds of exposure. Further susceptibility assays with standard reference bacteria showed that Lysol and 70% alcohol effectively killed > 99.99% (>8 log CFU drop) of Escherichia coli strain 7001, Staphylococcus aureus strain 6538, and Pseudomonas aeruginosa strain 10662 within 30 seconds of contact. Vinegar had a similar efficacy on the gram negatives but little or no effect on Staph aureus (only a 2-log CFU/ml reduction in 5 minutes!) The high prevalence of potential pathogens, some of which could be reservoirs of antibiotic resistance reveals a weak link in infection control and underscores the need for regular cleaning of personal and hand-held accessories with adequate considerations of their texture.展开更多
基金Sponsered by the National Natural Science Foundation of China (Grant No. 50678046)
文摘The high-active bacteria were screened from 8 dominant bacteria obtained from the natural water body,and then the bioaugmentation activated carbon was formed by hydraulic immobilization of the high-active bacteria. Plant-scale studies on removal characteristics of disinfection by-products formation potentials (DBPFP) by bioaugmentation activated carbon process were conducted for micro-polluted raw water treatment. The results show that the bioaugmentation activated carbon process has adopted better purification efficiency to THMFP and HAAFP than traditional biological activated carbon process,and that average removal efficiencies of THMFP and HAAFP can reach 35% and 39.7% during the test period,increasing by more than 10% compared with traditional biological activated carbon process. The removal efficiencies of THMFP and HAAFP are stable because of the biodegradation of the high-active bacteria and the adsorption of active carbon. The biodegradability of CHCl3 formation potential is better as compared with that of CHCl2Br and CHClBr2 formation potentials among THMFP,and high removal efficiency of CHCl3formation potential is obtained by bioaugmentation degradation of the high-active bacteria. The biodegradability of HAAFP is better in comparison with that of THMFP,and the chemical properties of HAAFP are propitious to adsorption of activated carbon. Thus,HAAFP is on predominance during the competitive removal process with THMFP.
基金This work was sponsored by National Natural Science Fundation Committee (No. 50238020).
文摘Objective To introduce a new sequential chlorination disinfection process in which short-term free chlorine and chloramine are sequentially added. Methods Pilot tests of this sequential chlorination were carried out in a drinking water plant. Results The sequential chlorination disinfection process had the same or better efficiency on microbe(including virus) inactivation compared with the free chlorine disinfection process. There seemed to be some synergetic disinfection effect between free chlorine and monochloramine because they attacked different targets. The sequential chlorination disinfection process resulted in 35.7%-77.0% TTHM formation and 36.6%-54.8% THAA5 formation less than the free chlorination process. The poorer the water quality was,the more advantage the sequential chlorination disinfection had over the free chlorination. Conclusion This process takes advantages of free chlorine's quick inactivation of microorganisms and chloramine's low disinfection by-product(DBP) yield and long-term residual effect,allowing simultaneous control of microbes and DBPs in an effective and economic way.
基金supported by the National Natural Science Foundation of China (No. 50538090)the Funds for Creative Research Groups of China (No. 50621804)the High-Tech Research and Development Program (863) of China (No. 2007AA06Z338).
文摘Dissolved organic matter(DOM) has been identified as precursor for disinfection by-products(DBPs) formation during chlorination. Recently,it has been demonstrated that the characteristics of DOM influence the DBPs formation mechanism. A study was,therefore,initiated to investigate the effects of DOM fractions on DBPs formation mechanism. In the chlorination process,organic acids are dominant precursors of total thihalomethanes(TTHM) because of the νC-O and unsaturated structures. Furthermore,the TTHM formation of organic acids was affected by pH more greatly. Based on the fluorescence spectroscopy analysis,DOM fractions contained several fluorescence substances. During chlorination,humic acid-like substances were found to exhibit high chlorine reactivity and hydrophobic organics decomposed to smaller molecules faster than hydrophilic organics even at lower chlorine dosages. Unlike hydrophobic fractions,hydrophilic organics showed no toxicity following chlorination,suggesting that the toxic structures in hydrophilic organics showed high chlorine reactivity during chlorination.
文摘The removal of disinfection by-products formation potential(DBPFP) in artificially intensified biological activated carbon(IBAC) process which is developed on the basis of traditional ozone granular activated carbon was evaluated. By IBAC removals of 31% and 68% for THMFP and HAAFP were obtained respectively. Under identical conditions, the removals of the same substances were 4% and 32% respectively only by the granular activated carbon(GAC) process. Compared with GAC, the high removal rates of the two formed potential substances were due to the increasing of bioactivity of the media and the synergistic capabilities of biological degradation cooperating with activated carbon adsorption of organic compounds. A clear linear correlation(R 2=0.9562 and R 2=0.9007) between DOC HAAFP removal rate and Empty Bed Contact Time(EBCT) of IBAC process was observed, while that between THMFP removal rate and EBCT of GAC was R 2=0.9782. In addition certain linear correlations between THMFP, HAAFP and UV 254 (R 2=0.855 and R 2=0.7702) were found for the treated water. For IBAC process there are also more advantages such as long backwashing cycle time, low backwashing intensity and prolonging activated carbon lifetime and so on.
基金supported by the National Natural Science Foundation of China (No.52200026)。
文摘Gravity-driven membrane(GDM)systems have been well developed previously;however,impacts of driving(i.e.,transmembrane)pressure on their performance received little attention,which may infuence GDM performance.In this study,we evaluated 4 GDM systems via altering the transmembrane pressure from 50 mbar to 150 mbar with 2 groups,treating surface water in Beijing,China.Results showed that less driving pressure was more favorable.Specifically,compared to groups(150 mbar),groups under a pressure of 50 mbar were found to have greater normalized permeability and lower total resistance.During the whole operation period,the quality of effuents was gradually improved.For example,the removal efficiency of UV254was significantly improved;particularly,under low driving pressure,the removal efficiency of UV254in PES GDM system increased by 11.91%,as compared to the corresponding system under high driving pressure.This observation was consistent with the reduction on disinfection by-products(DBPs)formation potential;groups under 50 mbar achieved better DBPs potential control,indicating the advantages of lower driving pressure.Biofilms were analyzed and responsible for these differences,and distinct distributions of bacteria communities of two GDM systems under 50 and 150 mbar may be responsible for various humic-like substances removal efficiency.Overall,GDM systems under less pressure should be considered and expected to provide suggestions on the design of GDM systems in real applications.
基金supported by the National Natural Science Foundation of China (Nos.22206050,22025601,21976133 and 52270047)the National Key Research and Development Program of China (No.2019YFC1805202)the State Key Laboratory of Pollution Control and Resource Reuse Foundation (No.PCRRK20014)。
文摘Permanganate/sulfite(Mn(VII)/S(IV))process is a promising pre-oxidation technology for sequestering the emerging organic contaminants in drinking water treatment plant.Iopamidol(IPM),a representative of iodinated X-ray contrast media,has been widely detected in water sources and has the risk of forming iodinated disinfection byproducts(I-DBPs)in water treatment system.In this study,we investigated the evolution of iodine species during the IPM degradation by the Mn(VII)/S(IV)process and its effect on the subsequent formation of I-DBPs during chlorination at pH 7.0 and 8.0.IPM could be effectively degraded in the Mn(VII)/S(IV)process at environmentally relevant pH(pH 7.0 and 8.0).The results of quenching and competitive oxidation kinetic experiments revealed that SO^(·-)_(4)was the major reactive oxidizing species contributing to the degradation of IPM whereas the contributions of HO·and reactive manganese species were negligible in the Mn(VII)/S(IV)process.I–and IO–3were generated while no HOI was detected during the degradation of IPM in the Mn(VII)/S(IV)process.The effects of IPM oxidation by Mn(VII)/S(IV)on the subsequent formation of chlorinated disinfection by-products(Cl-DBPs)during chlorination were related to the category of Cl-DBPs.The pre-oxidation of IPM by Mn(VII)/S(IV)resulted in the generation of I-DBPs during the disinfection process although no I-DBPs were detected if no pre-oxidation was applied.The finding of this study suggested that attention should be paid to the toxicity of DBPs when water containing iodinated organic contaminants is treated by Mn(VII)/S(IV)process or other pre-oxidation technologies.
基金This work was supported by the National Key Research and Development Program of China(No.2021YFC3200700)the National Natural Science Foundation of China(No.52170009)+2 种基金the International Cooperation Project of Shanghai Science and Technology Commission(No.20230714100)the Shanghai Soft Science Project(No.20692113900)the Fundamental Research Funds for the Central Universities.
文摘Identification and characterization of disinfection by-product(DBP)precursors could help optimize drinkingwater treatment processes and improve the quality of finishedwater.This study comprehensively investigated the characteristics of dissolved organic matter(DOM),the hydrophilicity and molecule weight(MW)of DBP precursor and DBP-associated toxicity along the typical full-scale treatment processes.The results showed that dissolved organic carbon and dissolved organic nitrogen content,the fluorescence intensity and the SUVA254 value in raw water significantly decreased after the whole treatment processes.Conventional treatment processes were in favor of the removal of high-MW and hydrophobic DOM,which are important precursors of trihalomethane and haloacetic acid.Compared with conventional treatment processes,Ozone integrated with biological activated carbon(O3-BAC)processes enhanced the removal efficiencies of DOM with different MW and hydrophobic fractions,leading to a further decrease in almost all DBP formation potential and DBP-associated toxicity.However,almost 50%of the detected DBP precursors in raw water has not been removed after the coagulation-sedimentation-filtration integrated with O3-BAC advanced treatment processes.These remaining precursors were found to be mainly hydrophilic and low-MW(<1.0 kDa)organics.Moreover,they would largely contribute to the formation of haloacetaldehydes and haloacetonitriles,which dominated the calculated cytotoxicity.Since current drinking water treatment process could not effectively control the highly toxic DBPs,the removal of hydrophilic and low-MW organics in drinking water treatment plants should be focused on in the future.
基金the Project of the National Key Research and Development Program of China(No.2021YFC1910404)the National Natural Science Foundation of China(Nos.52100008,52100184,and 52100142)+4 种基金the Funds of Hunan Science and Technology Innovation Project(China)(Nos.2021GK4055 and 2022SK2119)Natural Science Foundation of Hunan ProvinceChina(No.2021JJ40091)the Science and Technology Innovation Program of Hunan Province(China)(No.2021RC2056)the Project funded by China Postdoctoral Science Foundation(No.2021M701149).
文摘Sulfate radicals have been increasingly used for the pathogen inactivation due to their strong redox ability and high selectivity for electron-rich species in the last decade.The application of sulfate radicals in water disinfection has become a very promising technology.However,there is currently a lack of reviews of sulfate radicals inactivated pathogenic microorganisms.At the same time,less attention has been paid to disinfection by-products produced by the use of sulfate radicals to inactivate microorganisms.This paper begins with a brief overview of sulfate radicals’properties.Then,the progress in water disinfection by sulfate radicals is summarized.The mechanism and inactivation kinetics of inactivating microorganisms are briefly described.After that,the disinfection by-products produced by reactions of sulfate radicals with chlorine,bromine,iodide ions and organic halogens in water are also discussed.In response to these possible challenges,this article concludes with some specific solutions and future research directions.
基金supported by the Key Project of the National Natural Science Foundation of China(Nos.81630088,81273035,81325017)the Changjiang Scholars Program,Ministry of Education,China(No.T2014089).
文摘Haloacetaldehydes(HALs)are the third largest disinfection by-products(DBPs)class by mass in drinking water.Most of them alone in high doses are more cytotoxic and genotoxic than regulated DBPs.However,the toxic effects of mixed exposure to HALs at environmentally relevant levels are still unknown.Given that genotoxicity is critical for risk assessment,we employed multiple genotoxic tests including the Salmonella typhimurium revertant mutation assay(Ames assay),the single cell gel electrophoresis(SCGE)assay,the cytoplasmic blocking micronucleus(CBMN)assay,and theγ-H2AX assay to investigate the genotoxicity of HALs based on the HALs concentrations and components detected in the finished drinking water of Shanghai,China.The results demonstrated the concentrations of HALs were low,ranging from 0.04µg/L to 4.47µg/L,and the total concentration was 10.85µg/L.Although the mutagenicity of HALs was negative even at 1000-fold concentrations in the real world,mixed exposure to 100 and 1000-fold concentrations HALs resulted in DNA and chromosomal damage in human hepotocyte(HepG2)cells.HALs significantly increased the levels of reactive oxygen species(ROS)andγ-H2AX and activated nuclear factor erythroid-derived factor 2-related factor 2(NRF2)pathway-related protein expressions in HepG2 cells.The antioxidant NAC could ameliorate NRF2 pathway-related protein expression and DNA damage caused by HALs,suggesting that the genotoxicity of mixed exposure to HALs involved cellular oxidative stress and NRF2 pathway activation.
基金Fundação de Amparo a Pesquisa do Estado de São Paulo(FAPESP)and the Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq),São Paulo,Brazil for PhD scholarship(Process N°.141086/2015-7)financial support(Process No.870243/1997-7).
文摘The UV irradiation is used for removing Antibiotic Resistant Bacteria(ARB)and Antibiotic Resistance Genes(ARG)from wastewater treatment.Bacteriophages are viruses that infect within bacteria,are recognized for bacterial control.The influence of some parameters in quantification and performance influencing of pathogen demobilization could be considered in disinfection of wastewater.The comparison of Polyvalent phage(NE1)versus Coliphage(NE4)in suppressing a bacterium Escherichia coli(NDM-1:b-lactam-resistant)with UV irradiation was observed the efficacy in reduction of cells in the disinfection and parameter process.The results with the effect of UV-C irradiation on NDM-1 infected with 1%of NE4 showed a decrease of cells from 8×10^(6)to 2×10^(5)in 60 min with UV-C dose.The NDM1(E.coli)was infected with 1%of NE4(Polyvalent Phage)under magnetic stirring for 1 h,the cells count was 8×10^(6).After 1 h in UV-C e×posure,the cells number reached 3×10^(5).The NDM1 that was e×posed in 1 h of UV-C irradiation and then was infected with 1%of NE4.Cells counting were done 24 h after this procedure.These cells were e×posed in UV-C and showed a reduction in the number of cells from 1×10^(8)to 4×10^(5)after 60 min.The results indicate that bacteriophages can mitigate bacteria species,and combined the conventional water disinfection technologies that can support the microbial safety control strategies.
文摘Objective:To evaluate the application value of a refined quality control management model for a sterilization supply center.Methods:A retrospective analysis was conducted on the work situation of the sterilization supply center from January 2021 to January 2023.The work situation before January 31,2022,was classified as the control group;a routine quality control management model was implemented,and the work situation after January 31,2022,was classified as the observation group.The quality of medical device management and department satisfaction between the two groups were compared.Results:The timely recovery and supply rate,classification and cleaning pass rate,disinfection pass rate,packaging pass rate,sterilization pass rate,and department satisfaction score in the observation group were all higher than those of the control group(P<0.05).Conclusion:Implementing a refined quality control management model in the sterilization supply center can improve the quality management level of medical devices and department satisfaction and is worthy of promotion.
基金funding from the National Natural Science Foundation of China(Nos.52170021,42177051,and 41977317).
文摘Dissolved black carbon(DBC)released from biochar can be one of the potential disinfection by-products(DBPs)precursors in the dissolved organic matter pool.However,the physiochemical and structural properties of DBC and the effects on the development of DBPs and DBP formation potential(DBPFP)during the disinfection process remain unclear.In this study,the characteristics of two kinds of DBC,namely,animal-derived DBC(poultry litter DBC,PL-DBC)and plant-derived DBC(wheat straw DBC,WS-DBC),were investigated.The effects of different kinds of DBC on the evolution of DBPs and DBPFP in chlorine and chloramine disinfection processes were compared with natural organic matter(NOM).The results showed that the total DBPs concentrations derived from PL-DBC,WS-DBC and NOM were similar during chlorination(i.e.,61.23µg/L,64.59µg/L and 64.66µg/L,respectively)and chloramination(i.e.,44.63µg/L,44.42µg/L and 45.58µg/L,respectively).The lower total DBPs and DBPFP concentrations in chloramination could be attributed to the fact that the introduction of ammonia in chloramine inhibited the breaking of the bond between the disinfectant and the active group of the precursor.Additionally,DBC presented much lower total DBPFP concentrations than NOM in both chlorination and chloramination.However,both kinds of DBC tended to form more monochloroacetic acids and haloacetamides than NOM,which could result from the higher organic strength,higher protein matter,and nitrogen-rich soluble microbial products of DBC.
基金supported by the National Natural Science Foundation of China(Nos.51878648,52070184)Chinese Academy of Sciences(No.QYZDY-SSW-DQC004)。
文摘Disinfection by-products(DBPs) formed during water disinfection has drawn significant public concern due to its toxicity. Since the first discovery of the trihalomethanes in 1974,continued effort has been devoted on DBPs worldwide to investigate the formation mechanism, levels, toxicity and control measures in drinking water. This review summarizes the main achievements on DBP research in China, which included:(1) the investigation of known DBP occurrence in drinking water of China;(2) the enhanced removal of DBP precursor by water treatment process;(3) the disinfection optimization to minimize DBP formation;and(4) the identification of unknown DBPs in drinking water. Although the research of DBPs in China cover the whole formation process of DBPs, there is still a challenge in effectively controlling the drinking water quality risk induced by DBPs, an integrated research framework including chemistry, toxicology, engineering, and epidemiology is especially crucial.
基金supported by the National Natural Science Foundation of China (Nos. 5217000952091542)+6 种基金National Key Research and Development Program of China (2021YFC3200702)Science and Technology Innovation Action Plan of Shanghai Science and Technology Commission (No. 21DZ1202203)Program of Shanghai Academic Research Leader (No. 21XD1424000)International Cooperation Project of Shanghai Science and Technology Commission (No. 20230714100)Shanghai Soft Science Project (No. 20692113900)Tongji University Youth 100 Programsupported by Shanghai Post-doctoral Excellence Program (No. 2021327)。
文摘Disinfection by-products(DBPs), formed from the reactions of disinfectants with natural organic matter and halides in drinking water, were considered to be cytotoxic and genotoxic, and might trigger various cancers. The relatively low concentration of DBPs in finished water(low μg/L or even ng/L levels) and the interference from water matrix inhibited in situ determination of DBPs. Moreover, the further formation and degradation of DBPs by disinfectants during the holding time(several hours to several days) from sample collection to analysis could adversely affect the determination of DBPs. To obtain accurate, precise and reliable data of DBP occurrence and formation, robust and reliable sample preservation is indispensable. However, the commonly used quenching agents(e.g., sodium sulfite, sodium thiosulfate, and ascorbic acid) for sample preservation can decompose reactive DBPs by reductive dehalogenation. This study evaluated the performance of N-acetylcysteine(NAC) and glutathione(GSH) as quenching agents for the analysis of halogenated DBPs by investigating the stoichiometry of the disinfectant-quenching agent reaction, the formation of DBPs during chlor(am)ination of NAC or GSH, and the effects of NAC or GSH on the stability of 18 individual DBPs and total organic halogen(TOX). Based on the results of this study, NAC and GSH were considered to be ideal quenching agents for the analysis of most DBPs and TOX, except halonitromethanes.
基金financially supported by the National Key R&D Program of China(2016YFE0118800)National Natural Science Foundation of China(Nos.21577154,21590814 and 21621064)
文摘Disinfection is an indispensable water treatment process for killing harmful pathogens and protecting human health. However, the disinfection has caused significant public concern due to the formation of toxic disinfection by-products(DBPs). Lots of studies on disinfection and DBPs have been performed in the world since 1974. Although related studies in China started in1980 s, a great progress has been achieved during the last three decades. Therefore, this review summarized the main achievements on disinfection and DPBs studies in China, which included:(1) the occurrence of DBPs in water of China,(2) the identification and detection methods of DBPs,(3) the formation mechanisms of DBPs during disinfection process,(4) the toxicological effects and epidemiological surveys of DBPs,(5) the control and management countermeasures of DBPs in water disinfection, and(6) the challenges and chances of DBPs studies in future. It is expected that this review would provide useful information and reference for optimizing disinfection process, reducing DBPs formation and protecting human health.
文摘Background: Laboratory personnel is at risk of biological contamination leading to laboratory-acquired infections (LAIs). The use of disinfection products is essential in the prevention of these infections. This work aimed to evaluate the effectiveness of antimicrobial agents used in disinfection in bacteriology laboratories in Togo. Methods: This was a cross-sectional study conducted from June to December 2021 in all bacteriology laboratories in Togo. Swabs taken before and after disinfection of surfaces and staff hands were immediately plated on agar media. Counting and identification of isolated colonies were done after 24 hours of incubation. The ANOVA test was used to compare calculated means, prevalence ratio (PR) and 95% confidence intervals (CI) to compare bacterial frequencies. Results: A total of 393 samples were taken, of which 41.2% were from hands. Before disinfection, surfaces were more contaminated than hands with respectively 40.4% and 29.6% (PR = 1.3;CI 95% = [0.9 - 1.9]). After surface disinfection with 0.5% of chlorine solution, bacterial elimination was total, but partial on hands washed with soap, with residual contamination of 3.7%. A total of 108 strains were isolated before disinfection of which Klebsiella spp. 38.9% and Staphylococcus spp. 25.0%;after disinfection 4 strains were isolated of which: Staphylococcus spp. 75.0% and Klebsiella spp. 25.0%. Conclusion: Surface disinfection was more effective than hand washing with soap and water. We recommend proper hand washing.
文摘It is necessary to treat pathogen-infected water before its utilisation.Of conventionally used treatment methods,solar photocatalysis has gained considerable momentum owing to its operational simplicity and capacity to use freely and abundantly available solar energy.This article systematically reviewed the disinfection of water with photocatalysis.It addressed the concerns of microbial infection of water and the fundamentals behind its treatment with photocatalysis.It presented an in-depth description of pathogenic deactivation with powerful reactive oxygen species.Special emphasis was given to process intensification as it is an attractive technique that provides multifunctionality and/or equipment miniaturisation.Solar reactor design regarding mobilised/immobilised photocatalysts and compound parabolic concentrators were elucidated.Finally,key parameters governing photoperformance,corresponding trade-offs,and the need for their optimisation were discussed.Overall,this article is a single point of reference for researchers,environmentalists,and industrialists who address the ever-severing challenge of providing clean water whilst also maintaining energy sustainability.
基金Curtin University for an Australian Postgraduate AwardWater Research Australia and Chem Centre (Western Australia) for a PhD Top Up Scholarship
文摘Disinfection of water for human use is essential to protect against microbial disease;however, disinfection also leads to formation of disinfection by-products(DBPs), some of which are of health concern. From a chemical perspective, swimming pools are a complex matrix, with continual addition of a wide range of natural and anthropogenic chemicals via filling waters, disinfectant addition, pharmaceuticals and personal care products and human body excretions. Natural organic matter, trace amounts of DBPs and chlorine or chloramines may be introduced by the filling water, which is commonly disinfected distributed drinking water. Chlorine and/or bromine is continually introduced via the addition of chemical disinfectants to the pool. Human body excretions(sweat, urine and saliva) and pharmaceuticals and personal care products(sunscreens, cosmetics, hair products and lotions) are introduced by swimmers. High addition of disinfectant leads to a high formation of DBPs from reaction of some of the chemicals with the disinfectant.Swimming pool air is also of concern as volatile DBPs partition into the air above the pool.The presence of bromine leads to the formation of a wide range of bromo-and bromo/chloro-DBPs, and Br-DBPs are more toxic than their chlorinated analogues. This is particularly important for seawater-filled pools or pools using a bromine-based disinfectant.This review summarises chemical contaminants and DBPs in swimming pool waters, as well as in the air above pools. Factors that have been found to affect DBP formation in pools are discussed. The impact of the swimming pool environment on human health is reviewed.
文摘The potential role of personal items in the transmission of pathogens is poorly understood. In this study, we cultured bacteria of public health importance found on wristbands, determined whether there is a correlation between wristband material and prevalence, and tested three household disinfectants for efficacy in reducing bacteria on wristbands made of plastic, rubber, metal, and cloth, using standard microbiological assays. Total cultivable bacteria, Staphylococci, Enterobacteria (Escherichia coli), and Pseudomonas on 20 smartwatch wristbands were cultured from randomly recruited subjects. Nearly all wristbands (95%) were contaminated, with the highest average numbers of 3.46E+4 cfu/cm<sup>2</sup> and 1.52E+4 cfu/cm<sup>2</sup> on rubber and plastic bands respectively. Metallic gold and silver wristbands had zero to 18 cfu/cm<sup>2</sup>. While the high prevalence of Staphylococcus spp (85% of wristbands)—skin microbiota;was not unexpected, the occurrence of Pseudomonas spp (30%), and enteric bacteria (60%), even at relatively low numbers is of public health significance. Bacterial load on individual subjects varied remarkably with males and females harboring average total bacteria of 4.045 and 3.42 log<sub>10</sub>cfu/cm<sup>2</sup> of wristband, respectively. The most important predictor of wristband bacteria load was the texture of wristband material and activity (hygiene) of the subject at sampling time. Potential pathogens—Staphylococcus aureus (8143 cfu/cm<sup>2</sup>) and Pseudomonas spp. (1126 cfu/cm<sup>2</sup>) were most abundant on cloth and rubber wristbands, respectively, while the presence of the E. coli group was associated with animal handling activity by a veterinarian. Lysol Disinfectant Spray and 70% Ethanol were highly effective regardless of wristband material with >99.99% kill rate and a log cfu/cm<sup>2</sup> reduction of 3 - 4.0 and 3 - 4.5 respectively within 30 seconds. Apple Cider Vinegar (ACV) was not as potent. Only 2 - 3.5 log cfu/cm<sup>2</sup> drop was obtained after 120 seconds of exposure. Further susceptibility assays with standard reference bacteria showed that Lysol and 70% alcohol effectively killed > 99.99% (>8 log CFU drop) of Escherichia coli strain 7001, Staphylococcus aureus strain 6538, and Pseudomonas aeruginosa strain 10662 within 30 seconds of contact. Vinegar had a similar efficacy on the gram negatives but little or no effect on Staph aureus (only a 2-log CFU/ml reduction in 5 minutes!) The high prevalence of potential pathogens, some of which could be reservoirs of antibiotic resistance reveals a weak link in infection control and underscores the need for regular cleaning of personal and hand-held accessories with adequate considerations of their texture.
