Degradation of carbamazepine by the UVA-LED365/ClO2/NaClO process: Kinetics, mechanisms and DBPs yield.

A mixed oxidant of chlorine dioxide (ClO2) and NaClO was often used in water treatment. A novel UVA-LED (365 nm)-activated mixed ClO2/NaClO process was proposed for the degradation of micropollutants in this study. Carbamazepine (CBZ) was selected as the target pollutant. Compared with the UVA365/ClO2 process, the UVA365/ClO2/NaClO process can improve the degradation of CBZ, with the rate constant increasing from 2.11×10-4 sec-1 to 2.74×10-4 sec-1. In addition, the consumption of oxidants in the UVA365/ClO2/NaClO process (73.67%) can also be lower than that of UVA365/NaClO (86.42%). When the NaClO ratio increased, both the degradation efficiency of CBZ and the consumption of oxidants can increase in the UVA365/ClO2/NaClO process. The solution pH can affect the contribution of NaClO in the total oxidant ratio. When the pH range of 6.0-8.0, the combination process can generate more active species to promote the degradation of CBZ. The change of active species with oxidant molar ratio was investigated in the UVA365/ClO2/NaClO process. When ClO2 acted as the main oxidant, HO• and Cl• were the main active species, while when NaClO was the main oxidant, ClO• played a role in the system. Both chloride ion (Cl-), bicarbonate ion (HCO3-), and nitrate ion (NO3-) can promote the reaction system. As the concentration of NaClO in the reaction solution increased, the generation of chlorates will decrease. The UVA365/ClO2/NaClO process can effectively control the formation of volatile disinfection by-products (DBPs), and with the increase of ClO2 dosage, the formation of DBPs can also decrease.

Conocimiento en estudiantes de enfermería sobre desinfección terminal del área quirúrgica / Knowledge in nursing students about terminal disinfection of the surgical area

Determinar el nivel de conocimiento de los estudiantes de enfermería de la Universidad Técnica de Ambato sobre la desinfección terminal del área quirúrgica. Metodología: Esta investigación es cuantitativa, con enfoque descriptivo de cohorte transversal ya que el nivel de conocimiento se ha representado mediante tablas y gráficos para describir la problemática del periodo octubre 2023-febrero 2024. Resultados: Se evidencia el alto porcentaje de respuestas incorrectas por cada ítem por parte de los estudiantes. La categoría desinfección fue respondida de manera incorrecta con un porcentaje del 26%, la categoría proceso de desinfección con el 55,6%, la categoría aplicación del DAN con el 45.8%, la categoría desinfectante del DAN con el 36,2% y, por último, la categoría riesgo y prevención del DAN con el 29,2%. Conclusiones: El nivel de conocimiento de los estudiantes sobre desinfección es bajo, porque no están lo suficientemente motivados o interesados en el tema de desinfección[AU]

Determine the level of knowledge of nursing students at the Technical University of Ambato about terminal disinfection of the surgical area.Methodology:This research is quantitative, with a descriptive cross-sectional cohort approach and the level of knowledge has been represented through tables and graphs to describe the problems of the period October 2023-February 2024.Results:A high percentage of incorrect answers for each item by the students is evident. The disinfection category was answered incorrectly with a percentage of 26%, the disinfection process category with 55.6%, the DAN application category with 45.8%, the disinfectant category with 36.2% and, finally, the DAN risk and prevention category. with 29.2%. Conclusions:The level of knowledge of students about disinfection is low, because they are not sufficiently motivated or interested in the topic of disinfection[AU]

Determinar o nível de conhecimento dos estudantes de enfermagem da Universidade Técnica de Ambato sobre desinfecção terminal da área cirúrgica. Metodologia:Esta pesquisa é quantitativa, com abordagem descritiva de coorte transversal e o nível de conhecimento foi representado por meio de tabelas e gráficos para descrever os problemas do período outubro de 2023 a fevereiro de 2024.Resultados: Evidencia-se um alto percentual de respostas incorretas para cada item por parte dos alunos. A categoria desinfecção foi respondida incorretamente com um percentual de 26%, a categoria processo de desinfecção com 55,6%, a categoria aplicação DAN com 45,8%, a categoria desinfetante com 36,2% e, por último, a categoria risco e prevenção DAN. com 29,2%.Conclusões:O nível de conhecimento dos alunos sobre desinfecção é baixo, porque não estão suficientemente motivados ou interessados no tema da desinfecção[AU]

Effects of solid phase extraction conditions on molecular composition of unknown disinfection byproducts in chlorinated municipal wastewater based on FT-ICR-MS analysis.

Disinfection byproducts (DBPs) have been extensively investigated during the chlorination of water and wastewater. Although over 700 DBPs have been identified, more than 50% of the total organic halogen remains unknown. Solid phase extraction (SPE) has been emerged as a popular pretreatment approach for enrichment and desalting of unknown DBPs prior to the mass spectrometry analysis. However, the effects of SPE conditions on unknown DBPs in real wastewater have not yet been reported. Herein, three factors (acid types, pH values, and sorbent types) influencing the composition of DBPs in chlorinated municipal wastewater were systematically investigated by Fourier transform ion cyclotron resonance mass spectrometry and statistical analysis. The results indicated that the number of DBPs in different SPE conditions ranged from 280 to 706, and the majority ones were Br-DBPs and CHOX compounds. Compared with H2SO4, more common DBPs were found when using HCl and HCOOH to adjust the pH values of samples. The unique DBPs extracted at pH 1.0 and 2.0 generally owned higher modified aromaticity index (AImod) value and C number than at pH 3.0. The effect of acid types on the extracted DBPs was pH dependent, and the total number of extracted DBPs increased with the increasing of pH value. In terms of sorbent types, the unique DBPs in C18 sorbent possessed low O/C ratios (O/C < 0.6), whereas the unique ones in HLB sorbent owned high O/C ratios (O/C > 0.6). Compared with C18 and HLB sorbents, the unique DBPs extracted in PPL sorbent were characterized by relatively high AImod and DBE values. Based on mass difference analysis, 1496 precursors-DBPs pairs were identified in all extracted samples, with the highest number of bromine substitution reaction. Overall, the effects of SPE conditions on the composition of unknown DBPs should not be overlooked, and the amount and diversity of DBPs may be underestimated under a single SPE condition. This study provides new methodological references for the accurate identification of unknown DBPs with different characteristics in real wastewater.

Tuning the Locally Enhanced Electric Field Treatment (LEEFT) between Electrophysical and Electrochemical Mechanisms for Bacteria Inactivation.

Efficient drinking water disinfection methods are critical for public health. Locally enhanced electric field treatment (LEEFT) is an antimicrobial method that uses sharp structures, like metallic nanowires, to enhance the electric field at tips and cause bacteria inactivation. Electroporation is the originally designed mechanism of LEEFT. Although oxidation is typically undesired due to byproduct generation and electrode corrosion, it can enhance the overall disinfection efficiency. In this work, we conduct an operando investigation of LEEFT, in which we change the electrical parameters to tune the mechanisms between electrophysical electroporation and electrochemical oxidation. Pure electroporation (i.e., without detectable oxidation) could be achieved under a duty cycle of ≤0.1% and a pulse width of ≤2 µs. Applying 2 µs pulses at 7-8 kV/cm and 0.1% duty cycle results in 80-100% bacteria inactivation with pure electroporation. A higher chance of oxidation is found with a higher duty cycle and a longer pulse width, where the antimicrobial efficiency could also be enhanced. For water with a higher conductivity, a higher antimicrobial efficiency can be achieved under the same treatment conditions, and electrochemical reactions could be induced more easily. The findings shown in this work improve the fundamental understanding of LEEFT and help optimize the performance of LEEFT in real applications.

Disinfection of Medical Solid Waste through the Application Ozone Technology: Feasibility and Effectiveness Study.

Background: We aimed to determine the feasibility of ozone for disinfection of infectious solid waste in hospital. Methods: Spores of Bacillus atrophaeus were used to monitor the process of inactivating microbial agents using ozone in medical solid waste in the hospitals of Tabriz City, Iran. For this purpose, culture medium containing the mentioned bacteria was placed in the bags containing medical wastes. The ozone generator was equipped with a constant dose of 5 grams per liter, with a discharge of 1 and 3 liters per minute and contact time of 10 to 120 min. Then the ozone exposure indicators were incubated for 24-48h at 36 ± 1 °C and, finally, the absence of colony growth in the culture medium was considered as the success of ozone in disinfection of infectious solid waste. This process was performed with 4-time replications. Results: The complete removal of B. atrophaeus was obtained for non-compacted and compacted infectious solid waste, at contact time of 15 and 50 min, respectively. The efficiency of removal of B. atrophaeus by the process of wet ozone injection through a glass column was 100% in 30 minutes and by separate injection of water vapor into the contact tank was 100% in 50 minutes. The results of this study showed that the use of ozone technology was effective in the inactivation and destruction of microbial agents in medical solid waste. Conclusion: Employing different advanced technology of oxidization especially ozone in order to decrease the environmental pollution is considered as one of management approaches.

Sustainability and novel technologies to improve environmental cleaning in healthcare - Implications and considerations.

Along with emerging technologies electrolysed water (EW) systems have been proposed for cleaning and/or disinfection in clinical areas. There is evidence for the use of EW in food-handling and the dairy industry however there is lack of evidence for EW as an effective cleaning and disinfecting agent in a clinical setting. Existing publications mostly are either laboratory based or from non-clinical settings. This is in direct contrast to other approaches used in healthcare cleaning. The aim of this paper is to provide infection prevention and control professionals with a risk assessment checklist using an evaluation of electrolysed water as an example of the analysis and consideration required prior to the introduction of any new technology and, in particular, the inclusion of sustainability.

Effectiveness of photosensitized curcumin fibers, aloevera, amla juice and panchatulsi in disinfecting guttapercha cones.

Herbal remedies have demonstrated remarkable effects as anti-diabetic, anticancer, antimicrobials, immunological modulatory agent in liver problems, respiratory illnesses, and as beauty agents. The need for more affordable, readily accessible, and alternative medicines has led to a rise in the recognition of herbal drugs. Therefore, it is of interest to evaluate and compare the effectiveness of photosensitized curcumin fibers, Aloevera, Amla Juice and Pancha Tulsi in disinfecting guttapercha (GP) cones. It was observed that all experimental disinfectants were found to have greater antimicrobial action than the positive control in which no disinfectant was used. The order of antimicrobial action among different experimental disinfectants against Staphylococcus aureus and Enterococcus faecalis in disinfection of GP cones was in following order PanchaTulsi>Curcumin fibers >Amla juice > Aloe vera. It was concluded that all herbal disinfectants were found to have antimicrobial effectiveness in disinfection of GP cones with Panchtulsi having maximum disinfectant ability followed by photosensitized curcumin fibres.

Antimicrobial activity of laser assisted endodontic therapy in disinfecting root canals.

Light Amplified Stimulated Emission of Radiation (LASER) is nowadays widely studied regarding their use in endodontics and restorative dentistry. Therefore, it is of interest to evaluate the antibacterial activity of three types of LASERs namely CO2 LASER.Er, Cr:YSGG LASER and Diode LASER in disinfection of root canals. 70 patients (105 single rooted teeth) were included in the study. There was application of 2% Sodium Hypochlorite (NaOCl), 2780 nm Er,Cr:YSGG LASER, 900 nm Diode LASER and CO2 LASER. Microbial samples were collected from root canals both before and after the interventions through paper points. These parameters were evaluated in microbiology laboratory to obtain Log10 Colony Forming Units (CFUs). There was significant reduction in CFUs of microorganisms inside root canal in all three LASERs evaluated and NaOCl. The reduction in CFUs in LASERs was comparable to NaOCl. Then secondly we applied each LASER in combination with NaOCl. It was observed that reduction in CFU was greater when combination of LASER with NaOCl was applied as compared when applied alone. It can be inferred that LASER when applied with NaOCl can have significant role in disinfection of root canals.

Impact of Permanganate with Polyaluminium Chloride on Algae-laden Karst Water: Behaviors and Disinfection By-products Control.

The removal of algal organic matter (AOM) through water treatment processes is a major approach of reducing the formation of disinfection by-products (DBP). Here, the formation of DBP from AOM in karst water under different combination of potassium permanganate (KMnO4) and polyaluminium chloride (PACl) was investigated. The effect of divalent ions (Ca2+ and Mg2+) on DBP formation was traced by AOM chemistry variations. For DBP formation after KMnO4 preoxidation, total carbonaceous DBPs (C-DBPs) decreased by 12.9% but nitrogen-containing DBPs (N-DBPs) increased by 18.8%. Conversely, the C-DBPs further increased by 3.3% but N-DBPs reduced by 10.7% after the addition of PACl besides KMnO4 preoxidation. The variations of aromatic protein-like, soluble microbial products-like compounds and ultraviolet absorbance at 254 nm (UV254) were highly correlated with the formation of DBPs, which suggest aromatic substances strongly affect DBP behaviors at different treatment conditions. In the presence of divalent ions (Ca2+=135.86 mg/L, Mg2+=18.51 mg/L), the combination of KMnO4 and PACl was more effective in controlling DBP formation compared to the situation without Ca2+ and Mg2+. Specifically, trichloromethane formation was largely inhibited compared to the other tested DBPs, which may refer to complexation of electron-donating groups via divalent ions. While Ca2+ and Mg2+ may not affect the nature of α-carbon and amine groups, so the variation of haloacetonitriles (HANs) was not obvious. The study enhances the understanding of the DBP formation patterns, transformation of carbon and nitrogen by preoxidation-coagulation (KMnO4-PACl) treatment in algae-laden karst water.

Nanoplastics enhanced the developmental toxicity of aromatic disinfection byproducts to a marine polychaete at non-feeding early life stage.

Micro/nanoplastics can act as vectors for organic pollutants and enhance their toxicity, which has been attributed to the ingestion by organisms and the "Trojan horse effect". In this study, we disclosed a non-ingestion pathway for the toxicity enhancement effect of nanoplastics. Initially, the combined toxicity of polystyrene microplastics (40 µm) or nanoplastics (50 nm) with three disinfection byproducts (DBPs) to a marine polychaete, Platynereis dumerilii, was investigated. No toxic effect was observed for the micro/nanoplastics alone. The microplastics showed no effect on the toxicity of the three DBPs, whereas the nanoplastics significantly enhanced the toxicity of two aromatic DBPs when the polychaete was in its non-feeding early life stage throughout the exposure period. The microplastics showed no interaction with the P. dumerilii embryos, whereas the nanoplastics agglomerated strongly on the embryonic chorion and fully encapsulated the embryos. This could contribute to higher actual exposure concentrations in the microenvironment around the embryos, as the concentrations of the aromatic DBPs on the nanoplastics were1200 and 120 times higher than those in bulk solution. Our findings highlight an important and previously overlooked mechanism by which nanoplastics and organic pollutants, such as DBPs, pose a higher risk to marine species at their vulnerable early life stages. This study may contribute to a broader understanding of the environmental impacts of plastic pollution and underscore the necessity to mitigate their risks associated with DBPs.

Air disinfection performance of upper-room ultraviolet germicidal irradiation (UR-UVGI) system in a multi-compartment dental clinic.

Multi-compartment dental clinics present significant airborne cross-infection risks. Upper-room ultraviolet germicidal irradiation (UR-UVGI) system have shown promise in preventing airborne pathogens, but its available application data are insufficient in multi-compartment dental clinics. Therefore, the UR-UVGI system's performance in a multi-compartment dental clinic was comprehensively evaluated in this study. The accuracy of the turbulence and drift flux models was verified by experimental data from ultrasonic scaling. The effects of the ventilation rate, irradiation zone volume, and irradiation flux on UR-UVGI performance were analyzed using computational fluid dynamics coupled with a UV inactivation model. Different patient numbers were considered. The results showed that UR-UVGI significantly reduced virus concentrations and outperformed increased ventilation rates alone. At a ventilation rate of six air changes per hour (ACH), UR-UVGI with an irradiation zone volume of 20% and irradiation flux of 5 µW/cm2 achieved a 70.44% average virus reduction in the whole room (WR), outperforming the impact of doubling the ventilation rate from 6 to 12 ACH without UR-UVGI. The highest disinfection efficiency of UR-UVGI decreased for WRs with more patients. The compartment treating patients exhibited significantly lower disinfection efficiency than others. Moreover, optimal UR-UVGI performance occurs at lower ventilation rates, achieving over 80% virus disinfection in WR. Additionally, exceeding an irradiation zone volume of 20% or an irradiation flux of 5 µW/cm2 notably reduces the improvement rates of UR-UVGI performance. These findings provide a scientific reference for strategically applying UR-UVGI in multi-compartment dental clinics.

Blood trihalomethane and urinary haloacetic acid concentrations in relation to hypertension: An observational study among 1162 healthy men.

Disinfection byproducts (DBPs) have demonstrated cardiovascular and reproductive toxicity. However, the associations and mechanisms of DBP exposure in relation to hypertension among healthy young men, which are critical for gaining new insights into the prevention and treatment of male subfertility, remain unclear. In 2017-2018, we recruited 1162 healthy Chinese men. A single blood sample was collected and measured for trihalomethane (THM) concentrations (n = 956). Up to 2930 repeated urinary samples were collected at baseline and during follow-up periods and determined for haloacetic acid concentrations. Oxidative stress (OS) biomarkers were measured in within-subject pooled urinary samples (n = 1003). In total, 403 (34.68 %) participants were diagnosed with stage 1-2 hypertension (≥130/80 mmHg) and 108 (9.29 %) stage 2 hypertension (≥140/90 mmHg). In adjusted models, blood bromodichloromethane (BDCM) concentrations were positively associated with the risk of stage 1-2 and stage 2 hypertension [ORs= 1.48 (95 % CI: 1.15, 1. 91) and 1.65 (95 % CI: 1.08, 2.51), respectively, per 2.7-fold increase in BDCM concentrations]. Additionally, we found positive associations between DBP exposure biomarkers and urinary concentrations of 4-hydroxy-2-nonenal-mercapturic acid and 8-hydroxy-2-deoxyguanosine. However, these OS biomarkers were unrelated to hypertension. Our results suggest that BDCM exposure may be associated with a greater risk of hypertension among healthy young men.

Contaminated Duodenoscopes in Endoscopic Retrograde Cholangiopancreatography: Sensitivity of detection and risk of underdetection.

BACKGROUND AND AIMS: Periodic duodenoscope cultures are essential to timely detect contamination, but their sensitivity remains unknown. This study aims to determine the sensitivity of duodenoscope cultures and to estimate the prevalence of contaminated duodenoscope use. METHODS: We combined duodenoscope microbiological surveillance data from March 2015 to June 2022 with usage data to evaluate patient exposure to duodenoscopes contaminated with microorganisms of gut or oral origin (MGO). We identified duodenoscopes with repeated species-level contamination within a year and used molecular typing to confirm genetic relatedness. Genetically related microorganisms over multiple duodenoscope cultures of a single duodenoscope indicated a period of sustained contamination and a cluster was defined as overlapping periods of sustained contamination between different duodenoscopes. If microorganisms were not available for molecular analysis, we marked the period as unconfirmed. A sample was defined as false-negative if it did not show the target microorganism(s) in a period of sustained contamination. We used three scenarios to hypothesize about contaminated use and culture sensitivity. RESULTS: We included 556 duodenoscope cultures with 185 (33.3%) contaminated with MGO. The total usage of duodenoscopes was 5226. We identified one period of sustained contamination, six unconfirmed periods, and two clusters. Depending on our scenario assumptions, the percentage of contaminated use varied from 12.3% to 23.7%, and culture sensitivity ranged from 82.2% to 98.9%. CONCLUSIONS: Limited sensitivity of duodenoscope cultures leads to improper clearance of duodenoscopes for clinical use, increasing risks of outbreaks. The applicability of a single culture to end a duodenoscope's quarantine should be reevaluated.

Far-UVC 222 nm Treatment: Effects of Nitrate/Nitrite on Disinfection Byproduct Formation Potential.

Irradiation at far ultraviolet C (far-UVC) 222 nm by krypton chloride (KrCl*) excilamps can enhance microbial disinfection and micropollutant photolysis/oxidation. However, nitrate/nitrite, which absorbs strongly at 222 nm, may affect the formation of disinfection byproducts (DBPs). Herein, we evaluated model organic matter and real water samples and observed a substantial increase in the formation potential for trichloronitromethane (chloropicrin) (TCNM-FP), a nitrogenous DBP, by nitrate or nitrite after irradiation at 222 nm. At a disinfection dose of 100 mJ·cm-2, TCNM-FP of humic acids and fulvic acids increased from ∼0.4 to 25 and 43 µg·L-1, respectively, by the presence of 10 mg-N·L-1 nitrate. For the effect of nitrate concentration, the TCNM-FP peak was observed at 5-10 mg-N·L-1. Stronger fluence caused a greater increase of TCNM-FP. Similarly, the increase of TCNM-FP was also observed for wastewater and drinking water samples containing nitrate. Pretreatment using ozonation and coagulation, flocculation, and filtration or the addition of H2O2 can effectively control TCNM-FP. The formation potential of other DBPs was minorly affected by irradiation at 222 nm regardless of whether nitrate/nitrite was present. Overall, far-UVC 222 nm treatment poses the risk of increasing TCNM-FP of waters containing nitrate or nitrite at environmentally relevant concentrations and the mitigation strategies merit further research.

Pre-exposure to peracetic acid followed by UV treatment for deactivating vancomycin-resistant Enterococcus faecalis through intracellular attack.

Antimicrobial resistance (AMR) poses a global health threat to aquatic environments and its propagation is a hot topic. Therefore, deactivating antibiotic-resistant bacteria (ARB) and removing antibiotic resistance genes (ARGs) from water is crucial for controlling AMR transmission. Peracetic acid (PAA), which is known for its potent oxidizing properties and limited by-product formation, is emerging as a favorable disinfectant for water treatment. In this study, we aimed to assess the efficacy of pre-exposure to PAA followed by UV treatment (PAA-UV/PAA) compared with the simultaneous application of UV and PAA (UV/PAA). The focus was on deactivating vancomycin-resistant Enterococcus faecalis (VREfs), a typical ARB in water. Pre-exposure to PAA significantly enhanced the efficacy of subsequent UV/PAA treatment. At a UV fluence of 7.2 mJ cm-2, the PAA-UV/PAA method achieved a 6.21 log reduction in VREfs, surpassing the 1.29 log reduction observed with UV/PAA. Moreover, compared to UV/PAA, PAA-UV/PAA showed increased efficacy with longer pre-exposure times and higher PAA concentrations, maintaining superior performance across a broad pH range and in the presence of humic acid. Flow cytometry analysis indicated minimal cellular membrane damage using both methods. However, the assessments of superoxide dismutase (SOD) activity and adenosine triphosphate content revealed that PAA-UV/PAA induced greater oxidative stress under similar UV irradiation conditions, leading to slower bacterial regrowth. Specifically, SOD activity in PAA-UV/PAA surged to 3.06 times its baseline, exceeding the 1.73-fold increase under UV/PAA conditions. Additionally, pre-exposure to PAA amplified ARGs degradation and reduced resistance gene leakage, effectively mitigating the spread of AMR. Pre-exposure to 200 µM PAA for 10 and 20 min enhanced vanB gene removal efficiency by 0.14 log and 1.29 log, respectively. Our study provides a feasible approach for optimizing UV/PAA disinfection for efficient removal of ARB and ARGs.

Formation of the emerging disinfection byproducts halocyclopentadienes from phenolic compounds after chlorination.

Halocyclopentadienes (HCPDs) are an emerging class of alicyclic disinfection by-products (DBPs) with high toxicity in disinfected drinking water. However, their potential precursors remain unclear, which hinders the understanding of their formation and further development of control strategies. In this study, two HCPDs, 1,2,3,4-tetrachloro-1,3-cyclopentadiene (TCC) and 1,2,3,4,5,5-hexachloro-1,3-cyclopentadiene (HCC), were identified in chlorinated lignin and tannic acid samples for the first time. The chlorination of four lignin-like and two tannic-like phenolic model compounds confirmed that guaiacol and digallic acid can produce HCPDs. According to their structures, ortho-substituents of phenolic compounds were speculated to be crucial for HCPDs formation. The simulated disinfection of catechol, 2-ethoxyphenol (2-EOP), 2-propoxyphenol (2-POP) and 3,4-dihydroxy-5-methoxybenzoic acid (DH-5-MBA) with different ortho-substituents demonstrated that three of these compounds can generate HCPDs, except catechol, which further indicates that ortho-substituents, such as the methoxy, ethoxy and propoxy groups, contribute to HCPDs generation. Guaiacol was the simplest compound for generating HCPDs, and possible formation pathways during chlorination were proposed. Seven hydroxy-chlorocyclopentadienes were tentatively identified and are likely important intermediates of HCPDs formation. Additionally, TCC and HCC were confirmed in tap water and chlorinated SRNOM samples with total concentrations up to 11.07 ng/L and 65.66 ng/L, respectively, further demonstrating the wide existence of HCPDs and their precursors. This study reports the clear precursors of HCPDs and provides a theoretical foundation for controlling HCPDs formation in disinfected drinking water.

Long-term straw return enhanced the chlorine reactivity of soil DOM: Highlighting the molecular-level activity and transformation trade-offs.

Chemical properties and molecular diversity of dissolved organic matter (DOM) in agricultural soils are important for soil carbon dynamics and chlorine activity. Yet the chlorine reactivity of soil DOM at the molecular level under agricultural management practices remains unidentified. Here, we investigated the chlorine reactivity of soil DOM under long-term straw return and the molecular activities and transformations during chlorination. The 9-year straw return enhanced the chlorine reactivity of soil DOM, leading to increases in the production of traditional disinfection byproducts (DBPs) and decreases in the formation of emerging high molecular weight DBPs. C17HnOmCl1-2 and C22HnNmOzCl were the highest relative abundances of emerging DBPs. The emerging DBPs were primarily generated through chlorine substitution reactions, with their precursors exhibiting higher H/Cwa (1.47) and O/Cwa (0.41) ratios under straw return. The molecular transformation ability and inactive molecules of soil DOM under long-term straw return were reduced after chlorination, resulting in increased DOM instability. Chlorination led to a shift in the thermodynamic processes of soil DOM molecules from thermodynamically limited to thermodynamically favorable processes, and lignin-like compounds displayed higher potentials for transformation into protein/amino sugar-like compounds. C19H26O6 was identified as a sensitive formula for tracing chlorine reactivity under straw return, and a network illustrating the generation of DBPs from C19H26O6 was established. Overall, these results highlighted the strong chlorine reactivity of soil DOM under long-term straw return.

Changes in groundwater and surface water bacterial communities under disinfection processes: Chlorination, ozonization, photo-fenton and ultraviolet radiation.

Pathogenic bacteria, introduced in water sources through faecal contamination, have traditionally been investigated as individual species, leading to the establishment of microbial, sanitary, and environmental quality indicators. Recent advancements in our understanding of the microbiome and its intricate interactions within the human-microbiome-environment network advocate for a broader evaluation of the impact of disinfection on the entire microbial community. In this study, we conducted a comprehensive screening experiment involving four disinfection processes; ozone, ultraviolet radiation with wavelengths between 200 - 280 nm (UV-C), photo-Fenton, and chlorination, applied to two distinct water sources; surface (SW) and groundwater (GW). The cells that remained viable after treatment were recovered using Brain Heart Infusion (BHI) broth, and 16S rRNA gene sequencing was used for their identification. Our findings confirmed the presence of faecal contamination in the water sources and revealed distinct effects of each treatment on the recovered bacterial populations. The chlorination of groundwater samples likely had a greater impact on bacteria in a vegetative state than on spores. Consequently, this led to a higher abundance in the BHI cultures of sporulating bacteria such as Bacillus (increasing from 0.36 to 93.62 %), while ozonation led to an elevated recovery of Pseudomonas (increasing from 45.2 to 69.9 %). Conversely, in surface water, calcium hypochlorite and ozone treatments favored the selection of Staphylococcus and Bacillus, whose relative abundance in the cultures increased from 0 to 39.22 % and from 0.35 to 96.6 %, respectively. In groundwater, Pseudomonas was resistant to UV-C radiation and their relative abundance increased from 45.2 % to 93.56 %, while photo-Fenton was effective against this bacterial group decreasing its relative abundance to 0.46 %. However, other genera such as Bacteroides, Aeromonas, and Citrobacter seemed to be less injured by this disinfection process. BHI broth was successful in recovering various bacterial groups that exhibited resistance to sublethal water disinfection.

A promising approach utilising photothermal energy to disinfect the root canal system: An in vitro investigation.

This study aimed to assess root canal disinfection through various irrigation protocols, including a novel photothermal system called 'LEAP'. Mandibular premolars were infected with Enterococcus faecalis and divided into five groups for different treatments: Group 1: standard needle irrigation; Group 2: passive ultrasonic irrigation; Group 3: GentleWave; Group 4: LEAP; and Group 5: Group 1 + Group 4. Microbial counts were measured before (S1) and after disinfection (S2) using colony-forming units (CFU) and confocal laser scanning microscopy (CLSM). Results revealed a significant reduction in bacterial counts for all groups (p < 0.05). While the percentage of dead bacteria near the canal wall (0-50 µm) did not differ significantly, at 50-150 µm, LEAP and SNI + LEAP exhibited significantly higher bacterial reduction than other groups (p < 0.05). The findings indicate that LEAP is comparable to existing irrigation devices in the main root canal and notably superior in tubular disinfection.

Disinfection Byproducts of Haloacetaldehydes Disrupt Hepatic Lipid Metabolism and Induce Lipotoxicity in High-Fat Culture Conditions.

Unhealthy lifestyles, obesity, and environmental pollutants are strongly correlated with the development of nonalcoholic fatty liver disease (NAFLD). Haloacetaldehyde-associated disinfection byproducts (HAL-DBPs) at various multiples of concentrations found in finished drinking water together with high-fat (HF) were examined to gauge their mixed effects on hepatic lipid metabolism. Using new alternative methods (NAMs), studying effects in human cells in vitro for risk assessment, we investigated the combined effects of HF and HAL-DBPs on hepatic lipid metabolism and lipotoxicity in immortalized LO-2 human hepatocytes. Coexposure of HAL-DBPs at various multiples of environmental exposure levels with HF increased the levels of triglycerides, interfered with de novo lipogenesis, enhanced fatty acid oxidation, and inhibited the secretion of very low-density lipoproteins. Lipid accumulation caused by the coexposure of HAL-DBPs and HF also resulted in more severe lipotoxicity in these cells. Our results using an in vitro NAM-based method provide novel insights into metabolic reprogramming in hepatocytes due to coexposure of HF and HAL-DBPs and strongly suggest that the risk of NAFLD in sensitive populations due to HAL-DBPs and poor lifestyle deserves further investigation both with laboratory and epidemiological tools. We also discuss how results from our studies could be used in health risk assessments for HAL-DBPs.