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Water‐borne diseases resulting from pathogen infection are especially challenges in areas with inadequate sanitation and power supply. Here a novel disinfection system is developed for bacterial and viral inactivation in water using a self‐powered supercoiling‐mediated rotational triboelectric nanogenerator (S‐TENG) as a power source to drive a new oxidation‐assisted electroporation mechanism. Owing to its rational design, the S‐TENG achieves an ultrafast rotation (≈7500 rpm), therefore it enables a simultaneous nanowire‐enhanced localized electric field and generation of oxidative species resulting in high disinfection performance: >99.9999% microbial inactivation at a high flux of 15 000 L h‐1 m‐2. An integrated S‐TENG‐powered disinfection prototype using an enlarged electrode (area of 50 cm2) achieves complete disinfection when the gravity‐driven natural water flows through the whole system at a high rate (1 L min‐1). This rapid, self‐powered water disinfection method is a potential solution for urgent water disinfection needs during disasters and pandemics, and water disinfection in areas with inadequate power supply. [ABSTRACT FROM AUTHOR]

Contaminated drinking water is one of the main pathogen transmission pathways making waterborne illnesses such as diarrheal diseases and gastroenteritis a huge threat to public health, especially in the areas where sanitation facilities and gird power are inadequate such as rural and disaster hit areas. Self‐powered water disinfection systems are a promising solution in these cases. In this review paper, the authors provide an overview of the new and emerging methods of applying energy harvesting materials and devices as a source of power for water disinfection systems microbial disinfection in water by harnessing ambient forms of energy such as mechanical motion, light, and heat into electricity. The authors begin with a brief introduction of the different energy harvesting technologies commonly applied in water disinfection; triboelectric, piezoelectric, pyroelectric, and photovoltaic effects. Various microbial disinfection mechanisms and types of device construction are summarized. Then, a detailed discussion of the energy harvester‐driven water disinfection process is provided. Finally, challenges and perspectives regarding the future development of self‐powered water disinfection are described. [ABSTRACT FROM AUTHOR]

Recently, ultraviolet light-emitting diodes (UV-LEDs) and chlorine combined system has been employed as an emerging advanced oxidation process. However, UV-LEDs were commonly considered as monochromatic UV sources. In this study, the obvious quantum yields of chlorine photolysis under 265 nm and 280 nm LEDs irradiations were investigated with treating LEDs as polychromatic UV sources. Particularly, Φ obs-poly of HOCl and OCl⁻ for 265 nm LED were found to be 1.50 and 0.70 mol E−1, respectively, whereas Φ obs-poly of HOCl and OCl⁻ for 280 nm LED were 1.28 and 0.64 mol E−1, respectively. It was identified that Φ obs-poly were 5.66–14.63 % lower than Φ obs-mono. This suggests that obvious quantum yield using peak emission wavelength would overestimate the true quantum yield. The production of radical species in LED UV/chlorine systems were determined by the degradation of BA, and illustrated by a mathematical model. Different trends were observed for 265 nm and 280 nm LED UV/chlorine systems as pH increased from 5.0 to 10.0. As pH increased, the formation of OH continuously decreased in both 265 nm and 280 nm LED systems. The formation of Cl increased at neutral pH and more Cl and OH were formed due to the higher molar absorbance coefficient at 280 nm. The chlorine dose-dependent effects on radical productions at pH of 5.0, 7.5 and 10.0 were also assessed. At pH of 5.0, OH was the main radical product and had linear correlation with chlorine dose. At pH of 7.5, the productions of OH and Cl showed similar profiles that increased rapidly at low chlorine dosage and then slowed down. [Display omitted] • The UV/chlorine systems using polychromatic spectrum of LEDs as UV sources were evaluated. • Quantum yields of chlorine photolysis under 265 nm and 280 nm irradiation were determined. • The radical productions at various pH and chlorine dosages were investigated. • Anion and water matrix effects on BA degradation were studied. [ABSTRACT FROM AUTHOR]

This study provided an overview of established and emerging nanomaterial (NM)-enabled processes and devices for water disinfection for both centralized and decentralized systems. In addition to a discussion of major disinfection mechanisms, data on disinfection performance (shortest contact time for complete disinfection) and energy efficiency (electrical energy per order; E EO) were collected enabling assessments firstly for disinfection processes and then for disinfection devices. The NM-enabled electro-based disinfection process gained the highest disinfection efficiency with the lowest energy consumption compared with physical-based, peroxy-based, and photo-based disinfection processes owing to the unique disinfection mechanism and the direct mean of translating energy input to microbes. Among the established disinfection devices (e.g. , the stirred, the plug-flow, and the flow-through reactor), the flow-through reactor with mesh/membrane or 3-dimensional porous electrodes showed the highest disinfection performance and energy efficiency attributed to its highest mass transfer efficiency. Additionally, we also summarized recent knowledge about current and potential NMs separation and recovery methods as well as electrode strengthening and optimization strategies. Magnetic separation and robust immobilization (anchoring and coating) are feasible strategies to prompt the practical application of NM-enabled disinfection devices. Magnetic separation effectively solved the problem for the separation of evenly distributed particle-sized NMs from microbial solution and robust immobilization increased the stability of NM-modified electrodes and prevented these electrodes from degradation by hydraulic detachment and/or electrochemical dissolution. Furthermore, the study of computational fluid dynamics (CFD) was capable of simulating NM-enabled devices, which showed great potential for system optimization and reactor expansion. In this overview, we stressed the need to concern not only the treatment performance and energy efficiency of NM-enabled disinfection processes and devices but also the overall feasibility of system construction and operation for practical application. Image 1 • Brief overview of NM-enabled processes and devices for water disinfection. • Evaluation of NM-enabled processes/devices based on performance and energy efficiency. • Applying contact time and electrical energy per order (E EO) for assessment of processes and devices. • Discussion of influencing factors on contact time and E EO for NM-enabled disinfection. • Summary of NMs recovery and electrode strengthening methods for practical application. [ABSTRACT FROM AUTHOR]

Studies on ultraviolet light-emitting diode (UV-LED) water disinfection have shown advantages, such as safety, flexible design, and lower starting voltages. However, information about reactivation after UV-LED disinfection is limited, which is an important issue of UV light-based technology. In this study, the photoreactivation and dark repair of Escherichia coli after UV-LEDs and low pressure (LP) UV disinfection were compared. Four UV-LED units, 265 nm, 280 nm, the combination of 265 + 280 (50%), and 265 + 280 (75%) were tested. 265 nm LEDs was more effective than 280 nm LEDs and LP UV lamps for E. coli inactivation. No synergic effect for disinfection was observed from the combination of 265 and 280 nm LEDs. 265 nm LEDs had no different reactivation performances with that of LP UV, while 280 nm LEDs could significantly repress photoreactivation and dark repair at a low irradiation intensity of 6.9 mJ/cm 2 . Furthermore, the UV-induced damage of 280 nm LEDs was less repaired which was determined by endonuclease sensitive site (ESS) assay. The impaired protein activities by 280 nm LEDs might be one of the reasons that inhibited reactivation. A new reactivation rate constant, K max , was introduced into the logistic model to simulate the reactivation data, which showed positive relationship with the maximum survival ratio and was more reasonable to interpret the results of photoreactivation and dark repair. This study revealed the distinct roles of different UV lights in disinfection and reactivation, which is helpful for the future design of UV-LED equipment. [ABSTRACT FROM AUTHOR]

Ultraviolet (UV) irradiation is widely used for wastewater disinfection but suffers from low inactivation rates and can cause photoreactivation of microorganisms. Synergistic disinfection with UV and oxidants is promising for enhancing the inactivation performance. This review summarizes the inactivation effects on representative microorganisms by UV/hydrogen peroxide (H 2 O 2), UV/ozone (O 3), UV/persulfate (PS), UV/chlorine, and UV/chlorine dioxide (ClO 2). UV synergistic processes perform better than UV or an oxidant alone. UV mainly attacks the DNA or RNA in microorganisms; the oxidants H 2 O 2 and O 3 mainly attack the cell walls, cell membranes, and other external structures; and HOCl and ClO 2 enter cells and oxidize proteins and enzymes. Free radicals can have strong oxidation effects on cell walls, cell membranes, proteins, enzymes, and even DNA. At similar UV doses, the inactivation rates of Escherichia coli with UV alone, UV/H 2 O 2 , UV/O 3 , UV/PS (peroxydisulfate or peroxymonosulfate), and UV/chlorinated oxidant (chlorine, ClO 2 , and NH 2 Cl) range from 2.03 to 3.84 log, 2.62–4.30 log, 4.02–6.08 log, 2.93–5.07 log, and 3.78–6.55 log, respectively. The E. coli inactivation rates are in the order of UV/O 3 ≈ UV/Cl 2 > UV/PS > UV/H 2 O 2. This order is closely related to the redox potentials of the oxidants and quantum yields of the radicals. UV synergistic disinfection processes inhibit photoreactivation of E. coli in the order of UV/O 3 > UV/PS > UV/H 2 O 2. The activation mechanisms and formation pathways of free radicals with different UV-based synergistic processes are presented. In addition to generating HO·, O 3 can reduce the turbidity and chroma of wastewater to increase UV penetration, which improves the disinfection performance of UV/O 3. This knowledge will be useful for further development of the UV-based synergistic disinfection processes. [Display omitted] • Mechanisms of UV based synergistic process on enhanced microorganism inactivation were summarized. • Ozone improved UV disinfection performance via removing chroma, turbidity and forming·OH. • The inactivation rate of E. coli follows the order of UV/O 3 ≈UV/chlorine> UV/persulfate>UV/H 2 O 2. • Photoreactivation of bacteria can be well inhibited by UV based synergistic disinfection. [ABSTRACT FROM AUTHOR]

• For multi-cathode units, increasing the cathode number promoted the disinfection. • For stackable modules, the 3(3C + 1A) module was suggested as the best configuration. • Direct oxidation and indirect oxidation of H 2 O 2 were the disinfection mechanisms. • Synergistic effect between stackable units promoted electro-redox and disinfection. • Over-promoted H 2 O 2 competitive oxidation on the anodes restrained the disinfection. The stackable carbon fiber-based flow-through systems (m (n C + 1A)) were constructed, where the multi-cathode units (n C + 1A) were equipped with multiple cathodes (n C) and a counter anode (1A), and the m was the stackable numbers of the n C + 1A units. The configuration of the m (n C + 1A) systems with m and n values from 1 to 6 was optimized by comparing their disinfection performance toward a model pathogen (Escherichia coli) from the aspects of disinfection ability, energy consumption and HRT. For multi-cathode units (n C + 1A), increasing the cathode numbers (n) promoted the E. coli inactivation by the predominant direct oxidation on the anode. Among the stackable m (n C + 1A) modules, the 3(3C + 1A) module was recommended as the best configuration. In the stackable 3(3C + 1A) module with consecutive reduction-oxidation processes, the E. coli inactivation mechanisms were attributed to the direct oxidation on the anodes and H 2 O 2 -induced indirect oxidation on the cathodes. The synergistic effect between the stackable 3C + 1A units promoted the electro-redox of the electrodes and their disinfection ability, which was also accompanied by the enhancement of energy consumption for O 2 /H 2 O 2 mutual transformation on the electrodes. In turn, the modules with excessive stackable unit numbers (m > 3) over-promoted the competitive reaction of O 2 /H 2 O 2 mutual transformation, restraining the disinfection performance. [ABSTRACT FROM AUTHOR]