Kumiko Oguma

Pilot-scale UV LED treatment effectively disinfected wastewater but unexpectedly increased acetaminophen levels by cleaving its conjugated metabolites. This reveals a hidden release pathway that poses consequent environmental risks.

Demographic decline can leave water distribution systems (WDSs) oversized for the demand they now serve, increasing maintenance burdens and, under reduced flows, the risk of long water residence times. This paper examines the contraction of existing WDSs under sustained demand decline. Pipes are represented by separate physical-retention and hydraulic-activity variables, allowing reversible isolation without immediate asset removal. Reliability is protected through node-specific vertex-connectivity requirements, while candidate pipes are ranked using hydraulic utilisation and edge betweenness. Each proposed isolation is checked against hydraulic constraints, including a water-age guard that prevents new unacceptable conditions or further deterioration at nodes already exceeding the adopted limit. The approach is tested on two networks with contrasting topology: the densely looped Parete network in Italy and the more branched ky3 benchmark network from the United States. Approximately 29-32% of pipe length can be isolated in Parete, compared with 16-18% in ky3. Greater demand decline does not necessarily allow more of the network to be isolated, showing that feasible contraction depends on both topology and the hydraulic and reliability constraints that become limiting as demand falls. Water-age response also differs between the two networks, remaining low in Parete but becoming increasingly restrictive in ky3. Overall, the results support reversible pipe isolation as a practical adaptation strategy for oversized networks, contributing to long-term water security without immediate permanent decommissioning.

Objectives: We aimed to investigate the quality of platelets after storage following irradiation with ultraviolet C (UVC) light‐emitting diodes (LED). Background: Controlling transfusion‐related infections, particularly bacterial contamination of platelet concentrates (PCs), is urgently required. UVC‐LEDs have attracted considerable attention as potential solutions to this problem. Methods: PCs (5.5 mL) were irradiated with 265 nm UVC‐LED for up to 60 min and then stored at 22°C with shaking for 3 days. PC quality parameters, such as platelet count, biochemical profiles, including electrolytes and metabolism, activation markers and platelet aggregability, were analysed before and after storage. Prior to the storage study, to validate the appropriateness of the UVC‐LED dose used, the PCs were inoculated with Staphylococcus aureus or Bacillus cereus , and their colony‐forming ability was evaluated after irradiation with the same dose of UVC‐LED. Results: We confirmed that S. aureus and B. cereus colonies decreased with the irradiation dose (by 1.7 log and 1.2 log at 38.7 and 40.4 mJ cm ⁻² , respectively). Platelet count decreased immediately after 60‐minute irradiation to 32.5 mJ cm ⁻² , reaching approximately 80% of the level in the control without irradiation, but no further decrease was recorded after storage. The biochemical profiles and activation markers showed little alterations. Conclusion: These results indicate that UVC‐irradiated platelets maintain sufficient quality for practical use even after storage. Although this was a bench‐scale study, our findings suggest that irradiation of PCs with 265 nm UVC‐LED may enhance the safety of blood transfusions while preserving their efficacy.

Waterborne outbreaks caused by protozoan, bacterial, and viral pathogens continue to pose serious public health threats. However, comprehensive monitoring of all three major pathogen types remains uncommon, primarily due to the technical difficulty of simultaneously concentrating and characterizing these diverse microorganisms from a single water sample. Here, we evaluated a membrane adsorption followed by bead-beating-based direct nucleic acid extraction for its sensitivity in detecting waterborne pathogens. We further applied the optimized protocol to river water samples. Our results demonstrated that the use of magnesium chloride in combination with a mixed cellulose ester membrane filter (pore size: 0.8 μm) achieved the highest concentration efficiency for Cryptosporidium parvum , Legionella pneumophila , and murine norovirus (MNV), outperforming other methods utilizing the membrane with alternative pore sizes or membrane with another material (i.e., nylon). Furthermore, targeting rRNA of C. parvum instead of rDNA, or incorporating a preamplification step for the L. pneumophila mip gene and MNV, significantly improved the sensitivity. Notably, the 50% limit of detection for C. parvum using our method was comparable to that of traditional immunofluorescent antibody testing. Application of this method to river water further revealed a higher abundance of Bacteroides rRNA markers compared to their corresponding rDNA, underscoring the potential of rRNA-based targets for more sensitive bacterial detection. Importantly, when the target is genomic DNA or RNA, preamplification enables the use of a larger nucleic acids input volume, thereby enhancing sensitivity without introducing measurement bias. Overall, the combination of membrane adsorption and bead-beating-based direct nucleic acid extraction offers a sensitive, all-in-one approach for simultaneous detection of protozoa, bacteria, and viruses in environmental water. This method serves as an effective ‘screening’ tool for the presence of the three major types of waterborne microorganisms. Graphical

Ultraviolet light-emitting diodes (UV-LED) can be a good option for disinfecting water in small and decentralized facilities. A flow-through UV-LED disinfection module was evaluated at three remote locations in Japan. The disinfection efficiency of the module was monitored for over one year, targeting indigenous Escherichia coli, total coliforms, standard plate count, and heterotrophic plate count (HPC) bacteria. The physicochemical parameters of the source water, including UV transmittance (UVT), were also monitored to understand their natural fluctuation and impacts on UV disinfection. Overall, the UV-LED module showed efficient disinfection at all locations, achieving 2.7 log inactivation of E. coli at 30 L/min in a community-based water supply. HPC inactivation did not significantly differ among the three test sites (p > 0.01). One test site experienced a decrease in HPC inactivation after 10 months, whereas the other two sites did not show performance deterioration after one year. HPC inactivation was not correlated with the UVT of source water at any location, implying the difficulty to use UVT as a single parameter to predict disinfection efficiency in practical applications. This study demonstrates the effectiveness of UV-LED technology for water disinfection in small and decentralized water supply systems.

Ultraviolet (UV) light-emitting diodes (UV-LEDs), a disinfection technology, efficiently inactivate pathogens in water. However, the assessment of UV-LED treatment and the mechanisms of UV inactivation on viruses (especially enveloped viruses) are limited. In this study, the efficiency of UV-LED treatment (at 280 and 265 nm) on various viruses with different capsid and genome structures, including Aichivirus [AiV], coxsackievirus B3 [CV.B3], PhiX174 bacteriophage [PhiX174], T4 bacteriophage [T4], mouse hepatitis virus (MHV), and Pseudomonas Phi6 bacteriophage [Phi6], was investigated. Based on the fluence, all forms of tested viruses (non-enveloped and enveloped) were more sensitive to UV-LEDs at 265 nm than at 280 nm. Among the tested non-enveloped viruses, T4 was more sensitive to UV treatment (both at 280 nm and 265 nm) than the other viruses (AiV, CV.B3, and PhiX174). Between the enveloped viruses (MHV and Phi6), Phi6 was much more UV-LED-resistant (both at 280 nm and 265 nm) than MHV. Capsid integrity (RT-)qPCR was used to investigate the effects of UV-LED treatment on the virus structure, suggesting that capsid damage is less important in virus inactivation by UV-LEDs for both virus groups. Moreover, the lipid bilayer of enveloped viruses may not influence the efficiency of UV-LED treatment. Viral genomic properties (e.g., length, nucleic acid content, and structure) are considered key factors for virus sensitivity to UV-LED treatment.