UV Transmission Research Articles

Investigation of the effect of microplastics on the UV inactivation of antibiotic-resistant bacteria in water

This study investigated the effect of polyethylene and polyvinyl chloride microplastics on the UV fluence response curve for the inactivation of multidrug-resistant E. coli and enterococci in ultrapure water at pH 6.0 ± 0.1. In the absence of microplastics, the UV inactivation of the studied bacteria exhibited an initial resistance followed by a faster inactivation of free (dispersed) bacteria, while in the presence of microplastics, these 2 regimes were followed by an additional regime of slower or no inactivation related to microplastic-associated bacteria (i.e., bacteria aggregated with microplastics resulting in shielding bacteria from UV indicated by tailing at higher UV fluences). The magnitude of the negative effect of microplastics varied with different microplastics (type/particle size) and bacteria (Gram-negative and Gram-positive). Results showed that when the UV transmittance of the microplastic-containing water was not taken into account in calculating UV fluences, the effect of microplastics as protectors of bacteria was overestimated. A UV fluence-based double-exponential microbial inactivation model accounting for both free and microplastic-associated bacteria could describe well the disinfection data. The present study elucidated the effect of microplastics on the performance of UV disinfection, and the approach used herein to prove this concept may guide future research on the investigation of the possible effect of other particles including nanoplastics with different characteristics on the exposure response curve for the inactivation of various microorganisms by physical and chemical disinfection processes in different water and wastewater matrices.

Generalized Kubelka's theory for light transmission in multilayer materials and its application for UV light penetration in filtering facepiece respirators.

The spread of SARS‐CoV‐2 has resulted in the shortage of filtering facepiece respirators (FFRs). As a result, the use of ultraviolet (UV) irradiation for disinfection and reuse of FFRs has been the topic of much investigation. In this article, a mathematical model is developed based on Kubelka's theory to determine light transmission in multilayer materials, such as N95 masks. Using this model, the predicted UV transmittance and absorbance of a N95 mask layers were found to be in close agreement with the experimental values. In addition, when the mask was exposed to UV equally from both surfaces, the estimated minimum UV irradiance inside the N95 mask was 14.5% of the incident irradiance, suggesting a significant degree of light penetration. The proposed model provides a simple and practical methodology for the design and use of UV decontamination equipment for FFRs and other multilayer materials.

Fabrication and investigation on influence of metal oxide nanoparticles on thermal, flammability and UV characteristics of polyethylene glycol based phase change materials

The current study is aimed at the fabrication and property evaluation of form-stable phase change material (PCMs) nanocomposites films made by solvent casting method using Polyethylene Glycol (PEG) as working PCM and Polyvinyl Alcohol (PVA) as a supporting matrix, reinforced with Titanium Dioxide Nanoparticles (NTO). The influence of the incorporated metal oxide nanoparticles in varying concentrations (0.25–1 %) on the chemical, thermal, microstructural, UV resistance, and flammability characteristics for the developed nanocomposites has been thoroughly investigated. The resultant form-stable PCMs are characterized by FTIR and FE-SEM. Phase change behaviours and thermal stability of the prepared PCMs are determined by DSC and TGA analysis. T-History and thermal cycling tests have been carried out to access the charging-discharging time as well as the thermal reliability of the form-stable PCMs. The addition of the varying loadings of NTO particles to the optimized PEG/PVA composition significantly improves the phase change parameters, such as latent heat storage capacities from 65.59 J/g to 73.02 J/g and degree of supercooling from 18.93 to 17.03 respectively; along with the thermal stability of the nanocomposites with increasing order of nanoparticles concentrations. The presence of NTO particles in nanocomposites has proved to be effective in successfully reducing the UV transmittance across the films. The metal oxide filler also enhances the flame-retardant behaviour of the form-stable PCMs.

Acquisition methods for ultraviolet atmospheric transmittance at astronomical sites

Acquisition methods for ultraviolet atmospheric transmittance at astronomical sites

Optical Behavior of Human Skin Substitutes: Absorbance in the 200-400 nm UV Range.

The most recent generation of bioengineered human skin allows for the efficient treatment of patients with severe skin defects. Despite UV sunlight can seriously affect human skin, the optical behavior in the UV range of skin models is still unexplored. In the present study, absorbance and transmittance of the UGRSKIN bioartificial skin substitute generated with human skin cells combined with fibrin-agarose biomaterials were evaluated for: UV-C (200–280 nm), -B (280–315 nm), and -A (315–400 nm) spectral range after 7, 14, 21 and 28 days of ex vivo development. The epidermis of the bioartificial skin substitute was able to mature and differentiate in a time-dependent manner, expressing relevant molecules able to absorb most of the incoming UV radiation. Absorbance spectral behavior of the skin substitutes showed similar patterns to control native skin (VAF > 99.4%), with values 0.85–0.90 times lower than control values at 7 and 14- days and 1.05–1.10 times the control values at 21- and 28-days. UV absorbance increased, and UV transmission decreased with culture time, and comparable results to the control were found at 21 and 28 days. These findings support the use of samples corresponding to 21 or 28 days of development for clinical purposes due to their higher histological similarities with native skin, but also because of their absorbance of UV radiation.

UV‐induced degradation of high‐efficiency silicon PV modules with different cell architectures

AbstractDegradation from ultraviolet (UV) radiation has become prevalent in the front of solar cells due to the introduction of UV‐transmitting encapsulants in photovoltaic (PV) module construction. Here, we examine UV‐induced degradation (UVID) in various commercial, unencapsulated crystalline silicon cell technologies, including bifacial silicon heterojunction (HJ), interdigitated back contact (IBC), passivated emitter and rear contact (PERC), and passivated emitter rear totally diffused (PERT) solar cells. We performed UV exposure tests using UVA‐340 fluorescent lamps at 1.24 W·m−2 (at 340 nm) and 45°C through 4.02 MJ·m−2 (2000 h). Our results showed that modern cell architectures are more vulnerable to UVID, leading to a significant power decrease (−3.6% on average; −11.8% maximum) compared with the conventional aluminum back surface field (Al‐BSF) cells (<−1% on average). The power degradation is largely caused by the decrease in short‐circuit current and open‐circuit voltage. A greater power decrease is observed in bifacial cells with rear‐side exposure compared with those with front‐side exposure, indicating that the rear side is more susceptible to UV damage. Secondary ion mass spectroscopy (SIMS) confirmed an increase in hydrogen concentration near the Si/passivation interface in HJ and IBC cells after UV exposure; the excess of hydrogen could result in hydrogen‐induced degradation and subsequently cause higher recombination losses. Additionally, surface oxidation and hot‐carrier damage were identified in PERT cells. Using a spectral‐based analysis, we obtained an acceleration factor of 5× between unpackaged cells (containing a silicon nitride antireflective coating on the front) in the UV test and an encapsulated module (with the front glass and encapsulant blocking 90% of the UV at 294 nm and 353 nm, respectively) in outdoor conditions. From the analytical calculations, we show that a UV‐blocking encapsulant can reduce UV transmission in the module by an additional factor of ~50.

Spent coffee grounds: An intriguing biowaste reinforcement of thermoplastic starch with potential application in green packaging

AbstractWith respect to the explosion of single‐use plastic packaging consumption during the COVID‐19 pandemic, environmentally friendly substitutes are critically needful for sustainable development. Therefore, the present work focuses on the functional properties of bioplastic blends prepared through hot compressing molding of thermoplastic starch (TPS) and spent coffee grounds (SCG) in different ratios (0%–20% SCG) as the potential features of SCG were extensively employed in biocomposites for the first time. The insertion of dark brown SCG into TPS hindered UV transmission by 100% at 320 nm and 99.2% at 400 nm. Moreover, the samples with 15% and 20% SCG induced a surge in radical scavenging activity from 7.95% to over 92% at a concentration of 0.1 g/ml owing to the rich source of antioxidants in SCG. The lignin component and high carbon content also improved the thermal performance of TPS/SCG blends, enhancing thermal stability, delaying onset and maximum degradation temperatures, and achieving the HB rating in the UL‐94 test. Compared to a pure TPS matrix, TPS blends incorporating up to 10% SCG exhibited improvement in elastic modulus without deterioration of tensile strength.

A way to enhance the mechanical performance and UV visible‐light barrier of polyethylene terephthalate packaging material: Synthesis and application of takedaite (Ca3B2O6)

AbstractThe current study aimed to produce polyethylene terephthalate (PET)/takedaite (Ca3B2O6) composite bottles, an innovative packaging material with better performance. For this, Ca3B2O6 was firstly synthesized by sol–gel route and then it was incorporated to PET at five rates by extrusion. Finally, preform and PET bottles were produced by injection and stretch‐blow‐molding processes, respectively. The results showed that the use of Ca3B2O6 significantly improved the mechanical performance and UV transmittance of PET. Compared to pure PET, the load‐carrying capacity and burst strength enhanced by 133.66% and 54.16%, respectively. Environmental stress cracking (ESC) time increased from 0.3 to 18 min at 0.8% Ca3B2O6 concentration. Moreover, UV transmittance (~85%) of PET decreased to approximately ~18% in the visible region with the incorporation of 0.8 wt% Ca3B2O6. In terms of chemical degradation, Ca3B2O6 incorporation did not change the diethylene glycol (DEG) and isophthalic acid (IPA) rates, however it played an enhancing and reductive role in acetaldehyde (AA) and carboxylic acid (COOH) degradations, respectively. Accordingly, this novel product offers the opportunity to minimize the problems that may occur due to transportation/storage and photocatalytic degradation of food and beverages in PET packaging.

UV Transmission in Laminated glass: Effects on Plant Growth and Development

When glass is laminated for safety reasons, it usually blocks UV radiation partially or even completely when UV blocking materials are used. In the last decade, there has been an increasing interest in interlayers with high UV transmission, especially in relation to greenhouse applications. In this paper, we present an overview of the effects of UV transmittance on plant growth and development, in order to advice on the use of the high transmission interlayers versus the standard interlayers. Using UV transmitting films instead of UV blocking films has opportunities to alter plant growth and morphology. In general, plants grow more compact with increased UV transmittance, growth and biomass are reduced, flowering is stimulated (although the effects are species dependent), concentrations of secondary metabolites which are positive from nutritional perspective are stimulated and flower appearance (color) can be positively influenced. Pollination by bees is improved when UV is present and plant resilience to pests and diseases is improved. These results show that UV transmitting materials can have potential to be used in for example botanical gardens, office centers and garden markets, where producing biomass might even be unfavorable. On the contrary, the increased ornamental value by improved shape and flower color will be appreciated. Therefore, these aspects of transmitting UV to plants can have potential for markets where plant production is not the main goal.

EFFECT OF POST-PROCESSING TECHNIQUE ON THE MECHANICAL, TRIBOLOGICAL BEHAVIOR AND SURFACE CHARACTERISTICS OF 3D-PRINTED ACRYLONITRILE STYRENE ACRYLATE PARTS

Fused deposition modeling (FDM) is an extrusion-based three-dimensional (3D) printing technique that can find applications in communications, fashion, architecture, aerospace, automotive, medicine, and the education sector. The FDM printed part is affected by poor surface quality resulting from higher layer resolution and stair-stepping effects. Hence, this work aims at studying the effect of chemical treatment on the surface roughness, hardness, tensile strength, UV transmittance and tribological behavior of the acrylonitrile styrene acrylate (ASA) parts printed by the FDM process. Two different solvents namely, acetone and dichloromethane are considered for improving the surface finish of the ASA parts. The chemical treatment reduces the surface roughness, tensile strength, wear rate and improves the hardness by dissolving the external surfaces of printed specimens. The maximum surface finish and lesser UV transmittance are achieved from the sample treated with acetone. The higher hardness and low wear rate are noticed on the samples treated with dichloromethane.

All-optical tunable wavelength conversion in opaque nonlinear nanostructures

Abstract We demonstrate a simple, femtosecond-scale wavelength tunable, subwavelength-thick nanostructure that performs efficient wavelength conversion from the infrared to the ultraviolet. The output wavelength can be tuned by varying the input power of the infrared pump beam and/or relative delay of the control beam with respect to the pump beam, and does not require any external realignment of the system. The nanostructure is made of chalcogenide glass that possesses strong Kerr nonlinearity and high linear refractive index, leading to strong field enhancement at Mie resonances. Although, as many other materials, chalcogenide glasses absorb in the ultraviolet range, fundamental phase-locking mechanism between the pump and the inhomogeneous portion of the third-harmonic signal enables ultraviolet transmission with little or no absorption.

Comment on “Comparison of ozone measurement methods in biomass burning smoke: an evaluation under field and laboratory conditions” by Long et al. (2021)

Abstract. Long et al. (2021) conducted a detailed study of possible interferences in measurements of surface O3 by UV spectroscopy, which measures the UV transmission in ambient and O3-scrubbed air. While we appreciate the careful work done in this analysis, there were several omissions, and in one case, the type of scrubber used was misidentified as manganese dioxide (MnO2) when in fact it was manganese chloride (MnCl2). This misidentification led to the erroneous conclusion that all UV-based O3 instruments employing solid-phase catalytic scrubbers exhibit significant positive artifacts, whereas previous research found this not to be the case when employing MnO2 scrubber types. While the Long et al. (2021) study, and our results, confirm the substantial bias in instruments employing an MnCl2 scrubber, a replication of the earlier work with an MnO2 scrubber type and no humidity correction is needed.

Turing Pattern‐Inspired Highly Transparent Wood for Multifunctional Smart Glass with Superior Thermal Management and UV‐Blocking Ability

AbstractTransparent wood for smart glass can decrease indoor energy consumption, while simultaneously offering a comfortable indoor temperature and facilitating effective light harvesting. However, high transparency and ultraviolet (UV)‐blocking ability are mutually exclusive in wood‐based materials due to the presence of lignin. Herein, a Turing pattern‐inspired highly transparent wood (TP‐TW) is fabricated via infiltrating the thermal management materials doped‐epoxy (TMM‐epoxy) into the delignified wood with a Turing pattern. Afterward, the Turing pattern possesses outstanding optical properties (high visible transmittance of ≈76% and low UV transmittance of ≈15%). Moreover, TP‐TW can reduce adverse effects caused by indoor temperature fluctuation and outdoor sunlight, demonstrating high latent heat (25.30 J g−1) and low near‐infrared transmittance. Compared with glass, TP‐TW exhibits a low thermal conductivity of 0.21 W m−1 K−1 and excellent shock‐resistant characteristics. Taken together, these results indicate that TP‐TW is an attractive material for smart glass applications.

Anti-UV and hydrophobic dual-functional coating fabrication for flame retardant polyester fabrics by surface-initiated PET RAFT technique

Inspired by the flourish of living radical polymerization (LRP), surface-initiated LPR technology shows great potential in good control and accurate tailoring of target polymer coatings. In this work, surface-initiated photoinduced electron transfer-reversible addition-fragmentation chain transfer polymerization (SI-PET-RAFT) was employed as a facile synthetic rout for the fabrication of surface-tethered polymeric brushes with anti-UV and hydrophobic properties for flame retardant polyester fabrics (FRPET). Firstly, RAFT agent 4-Cyano-4-[(dodecyl sulfanyl thiocarbonyl) sulfanyl] pentanoic acid (CDTPA) was grafted onto polydopamine (PDA) deposited FRPET, followed by the controlled growth of glycidyl methacrylate (GMA) onto polyester fabrics via SI-PET-RAFT method. Finally, benzotriazole anti-UV agents were grafted as secondary functionalization. According to SEM-EDS and XPS analysis, PGMA has been immobilized successfully onto the surface of FRPET fabrics. An efficient PET RAFT polymerization of GMA with low dispersity (Ð<1.2), temporal control, and chain-end fidelity was achieved under mild yellow light irradiation (λmax = 570 nm, 4 W/m2). It also exhibited the feasibility of polymerization under natural sunlight and oxygen tolerance. The flame retardant, UV resistant and hydrophobic properties of the treated fabrics were investigated. In the microscale combustion calorimetry test, the peak heat release rate (PHRR) effectively decreased by 59.50%. In the cone calorimetry test, the PHRR and total heat release also reduced. The melt-dripping was eliminated in the vertical flaming test and reached V-0 rating with LOI value of 28%. The UV transmittance of the fabric decreased to<4%, meeting the standard of UV resistant fabric and the water contact angle reached 125°, thus making flame retardant polyester fabric have good hydrophobicity. Besides, it also kept good durability in flame retardancy, UV shielding and water repellent. This study provides new insights into the surface engineering of photoregulated LRP techniques for multi-functional coating synthesis.

Two microfluidic chips based on Rayleigh surface acoustic waves for controllable synthesis of silver nanoparticles: A comparison

Based on the biocompatibility and non-invasive nature of acoustically driven microfluidics, two microfluidic chips with Rayleigh surface acoustic waves (SAWs) as the driving source are proposed for micro-scale mixing: traveling surface acoustic wave (TSAW) and standing surface acoustic wave (SSAW) chips. This paper presents the first comparison of the controllable synthesis of silver nanoparticles (AgNPs) by TSAW chip and SSAW chip. The effect of peak-to-peak voltage and inlet flow rate on the micro-mixing performance of the two chips is investigated in focus. First, based on the finite element theory, the simulation software COMSOL is used to compare and analyze the mixing performance of the two chips. Then, a series of experiments of AgNPs synthesis is carried out combining with the liquid-phase reduction method. The difference in the results is characterized by UV spectroscopy and transmission electron microscope (TEM). The simulation results reveal that, under the same conditions, the SSAW chip transmits more energy to the fluid, which can effectively disturb the fluid and destroy the laminar flow interface. That is, it is easier to achieve rapid and uniform mixing with a better micro-mixing effect. As the peak-to-peak voltage increases or the inlet flow rate relatively decreases, the mixing effect of the SSAW chip gradually becomes better. However, experimental results indicate that the TSAW chip can synthesize AgNPs with higher concentration, better monodispersity, and smaller size deviation. As the peak-to-peak voltage increases or the inlet flow rate relatively decreases, it is easier to synthesize AgNPs with better quality. The comparison of the simulation and experimental results of the two chips can provide guidelines for the analysis of micro-scale mixing performance and practical applications of microfluidic chips driven by SAWs.

Realization of Enlarged Birefringence from BaCdBe2(BO3)2F2 to NaMgBe2(BO3)2F via the Cation Size Effect as a Potential Deep-Ultraviolet Birefringent Material.

Birefringence, as one of the most important factors for birefringent materials, governs their performances in applications. In this study, two previously unreported beryllium borates, BaCdBe2(BO3)2F2 (BDBBF) and NaMgBe2(BO3)2F (NMBBF), have been rationally designed by modulating interstitial cations. When smaller sizes of the cations are used, the crystal structure of NMBBF exhibits closer-packed 2D [Be6B6O12F3]∞ double layers rather than the 2D [Be3B3O6F3]∞ single layers in the crystal structure of BDBBF. The ultraviolet (UV) transmittance spectrum indicates that the short UV absorption edges of BDBBF and NMBBF are below 200 nm. The results from both theoretical calculations (theo.) and experimental characterizations (exp.) reveal enlarged birefringence from BDBBF (0.067 at 589 nm from theo. and 0.059 at 546.1 nm from exp.) to NMBBF (0.078 at 589 nm from theo. and 0.081 at 546.1 nm from exp.). Because of its excellent structure-based optical properties, NMBBF has the potential to be a deep-UV birefringent material. Our structural comparison and discussion provide a scope to aid in the design of potential deep-UV birefringent materials with large birefringence.

An integrated multifunctional membrane via broadband light modulation for greenhouse smart windows

Smart windows that regulate solar irradiation (including ultraviolet UV, visible and infrared) have emerged as an exciting research area for energy conservation, privacy protection and organism healthcare. However, scalable, low cost and robust smart windows with broadband light modulation are still challengeable for practical applications. Here, an integrated smart membrane with capability of managing the light wavelength from UV, visible (Vis) to near infrared (NIR) band via facile spray coating is reported. The smart membrane consists of the upper ITO rich layer, bottom TiO 2 /SiO 2 NPs layer and a bulk elastomeric PDMS as matrix. Due to the NIR reflection and UV absorption, the smart membrane shows high Vis transmittance and moderate UV and NIR transmittance under relaxed state. Due to Mie scattering from vacuum cavity, under stretching (50%), UV, Vis and NIR transmittance could be dramatically decreased from 40% to 5% (380 nm), from 70% to 5% and from 70% to 10%, respectively, indicating highly efficient and sensitive management. In particular, the application in greenhouse exhibits excellent properties in plants protection, IR cooling and privacy preserving. We believe that this work will pave a facile and low-cost approach for a novel class of integrated smart windows via broadband light modulation. We present an integrated smart membrane with capability of tuning the light wavelength from UV, visible (Vis) to near infrared (NIR) band via facile spray coating. This membrane consists of the upper ITO rich layer, bottom TiO 2 /SiO 2 NPs layer and a bulk elastomeric PDMS as matrix. The excellent UV–Vis–NIR management via stretching endows it with privacy preserving, energy saving, plants protection, etc. • We provide a facile and scalable strategy for smart windows via UV–Vis–NIR modulation. • The smart membrane indicates highly efficient and sensitive UV–Vis–NIR management. • Our study highlights their potentials in plants protection, energy saving and privacy preserving.

A quantitative assessment of the VO line list: Inaccuracies hamper high-resolution VO detections in exoplanet atmospheres

Context.Metal hydrides and oxides are important species in hot-Jupiters since they can affect their energy budgets and the thermal structure of their atmospheres. One such species is vanadium-oxide (VO), which is prominent in stellar M-dwarf spectra. Evidence for VO has been found in the low-resolution transmission spectrum of WASP-121b, but this has not been confirmed at high resolution. It has been suggested that this is due to inaccuracies in its line list.Aims.In this paper, we quantitatively evaluate the VO line list and assess whether inaccuracies are indeed the reason for the non-detections at high resolution in WASP-121b. Furthermore, we investigate whether the detectability can be improved by selecting only those lines associated with the most accurate quantum transitions.Methods.A cross-correlation analysis was applied to archival High Accuracy Radial velocity Planet Searcher and CARMENES spectra of several M-dwarfs. VO cross-correlation signals from the spectra were compared with those in which synthetic VO models were injected, providing an estimate of the ratio between the potential strength (in case of a perfect model) and the observed strength of the signal. This was repeated for the reduced model covering the most accurate quantum transitions. The findings were subsequently fed into injection and recovery tests of VO in a Ultraviolet and Visual Echelle Spectrograph transmission spectrum of WASP-121b.Results.We find that inaccuracies cause cross-correlation signals from VO in M-dwarf spectra to be suppressed by about a factor 2.1 and 1.1 for the complete and reduced line lists, respectively, corresponding to a reduced observing efficiency of a factor 4.3 and 1.2. The reduced line list outperforms the complete line list in recovering the actual VO signal in the M-dwarf spectra by about a factor of 1.8. Neither line list results in a VO detection in WASP-121b. Injection tests show that with the reduced efficiency of the line lists, the potential signal as seen at low resolution is not detectable in these data.

Enhanced optical and electrical properties of CeO2NPs/chitosan nanocomposites

Cerium oxide nanoparticles (CeO2NPs) of different ratios (x = 5, 10, 15, and 20 in wt%) are successfully incorporated into chitosan (CS) to synthesize CeO2NPs/CS nanocomposites by solution cast method. FTIR and XRD analysis confirmed the effective incorporation of CeO2NPs into chitosan nanocomposites. TGA and DTG showed that the thermal stability of the as-prepared nanocomposites is improved. The CeO2NPs/CS nanocomposites exhibited enhanced light absorption capacity in the UV-visible range as x increases, owing to the CeO2NPs’ large bandgap. The transmittance of UV decreased for x = 10 and 15 nanocomposites. Light scattering enhanced for x = 5 and 10 nanocomposites, increasing reflectance. Compared to CS (5.3 eV), the optical energy bandgap lowers to 4.94 eV and 5.1 eV, respectively. Impedance spectroscopy research validates the impedance spectroscopy parameters’ dependency on CeO2NPs concentrations. Because of the growth of multiple polarization types, generating interfaces of numerous defects, and space charge polarization, the dielectric constant increases with increasing x (up to x = 15). The dc conductivity (σ DC) and the frequency exponent (S) are estimated using the universal Josher’s power law and applied to the ac conductivity data (σ AC). Obviously, (S) decreases with increasing temperature, which refers to the electrical conductivity that follows the hopping mechanism. In addition, according to the CBH model, the Coulomb barrier of charge carriers (Um) is estimated, showing decreasing values as increasing x and recording the lowest value for x = 15 nanocomposites. Nyquist plots (Z″&Z′) indicate one semicircle arc behavior for all samples. As x rises, the radius of semicircular arcs reduces, suggesting that (σ DC) increases. The enhanced characteristics of CeO2NPs/CS nanocomposites make them suitable for future bio-applications.

Granular Activated Carbon Contactors for Small Water System DBP Compliance

Key TakeawaysTwo small surface water systems located on islands off the state of Washington's coast implemented a sustainable treatment approach that minimizes disinfection byproduct (DBP) formation.Installing and operating granular activated carbon (GAC) contactors has resulted in full compliance with DBP levels, while achieving other water quality improvements.Operators use ultraviolet transmittance to assess direct filtration treatment for removal of DBP precursors and to determine GAC media performance in real time.