UV LED wastewater disinfection: The future is upon us.

The world's first full-scale, 280 nm UV LED reactor for wastewater disinfection was tested at flows of 545 and 817 m day. The system achieved > 3 average log reduction of total coliform at 545 m day and the 817 m day flow rate achieved over > 2.5 average log reduction for all operational conditions.

A critical review of ultra-violet light emitting diodes as a one water disinfection technology.

UV light emitting diode (LED) disinfection technologies have advanced over the last decade and expanded the design space for applications in point of use, industrial, and now full-scale water treatment. This literature review examines the progression of UV LED technologies from 2007 to 2023 using key features such as total optical power, price, and wall-plug efficiency. The review found that optical power is increasing while the price per Watt is decreasing; however, the wall plug energy (WPE) is slowly improving over the last decade.

Biofilm inactivation using LED systems emitting germicidal UV and antimicrobial blue light.

Biofilms have been widely detected in water distribution and water storage systems posing potential risks to drinking water safety by harboring and shedding pathogens. Light-based disinfection methods, such as germicidal ultraviolet (UV) and antimicrobial blue light (aBL), could serve as non-chemical alternatives for biofilm control. This study investigated the inactivation of pure-culture Pseudomonas aeruginosa biofilms and mixed-culture biofilms using three distinct light-based disinfection methods: a low-pressure (LP) UV lamp emitting at 254 nm, a UV light emitting diode (LED) at 270 nm, and an aBL LED at 405 nm.

Optimizing radical yield from free chlorine with tailored UV light emitting diode emission spectra.

Novel UV sources, which do not contain mercury, provide the opportunity for enhancement of current oxidation technologies through spectral optimization, minimizing inefficiencies that currently limit conventional technology. Wastewater reuse is the primary full-scale application of UV advanced oxidation processes (AOPs) in practice but any background absorbance and the low molar absorption by conventional radical promoters (hydrogen peroxide) have historically limited their system efficiency, resulting in the underutilization of photons in a reactor. This bench-scale research evaluated use of longer wavelength UV light emitting diodes (265, 280, and 300 nm) matched with free chlorine to optimize the utilization of photons for advanced oxidation.

Rapid Inactivation of Fungal Spores in Drinking Water by Far-UVC Photolysis of Free Chlorine.

Effective and affordable disinfection technology is one key to achieving Sustainable Development Goal 6. In this work, we develop a process by integrating Far-UVC irradiation at 222 nm with free chlorine (UV/chlorine) for rapid inactivation of the chlorine-resistant and opportunistic spores in drinking water. The UV/chlorine process achieves a 5.

Inactivation efficacy and mechanisms of wavelength-specific UV sources for various strains of Legionella pneumophila serogroup 1.

Infections of Legionnaires' disease in the United States caused by Legionella have increased ninefold between the years 2000-2018. Legionella harbored in biofilms or inside amoeba within premise plumbing can be more resistant to disinfectants, thus causing treatment challenges. Ultraviolet-light emitting diodes (UV-LEDs) are an emerging water disinfection technology with several advantages over conventional UV lamps.

Accelerated Ultraviolet Treatment of Carbamazepine and NDMA in Water under 222 nm Irradiation.

Krypton chloride (KrCl*) excimer ultraviolet (UV) light may provide advantages for contaminant degradation compared to conventional low-pressure (LP) UV. Direct and indirect photolysis as well as UV/hydrogen peroxide-driven advanced oxidation (AOP) of two chemical contaminants were investigated in laboratory grade water (LGW) and treated secondary effluent (SE) for LPUV and filtered KrCl* excimer lamps emitting at 254 and 222 nm, respectively. Carbamazepine (CBZ) and -nitrosodimethylamine (NDMA) were chosen because of their unique molar absorption coefficient profiles, quantum yields (QYs) at 254 nm, and reaction rate constants with hydroxyl radical.

Study design and baseline to evaluate water service provision among peri-urban communities in Kasai Oriental, Democratic Republic of the Congo.

We present a study design and baseline results to establish the impact of interventions on peri-urban water access, security and quality in Kasai Oriental province of the Democratic Republic of the Congo. In standard development practice, program performance is tracked via monitoring and evaluation frameworks of varying sophistication and rigor. Monitoring and evaluation, while usually occurring nearly concurrently with program delivery, may or may not measure parameters that can identify performance with respect to the project's overall goals.

The effects of racism, social exclusion, and discrimination on achieving universal safe water and sanitation in high-income countries.

Drinking water and sanitation services in high-income countries typically bring widespread health and other benefits to their populations. Yet gaps in this essential public health infrastructure persist, driven by structural inequalities, racism, poverty, housing instability, migration, climate change, insufficient continued investment, and poor planning. Although the burden of disease attributable to these gaps is mostly uncharacterised in high-income settings, case studies from marginalised communities and data from targeted studies of microbial and chemical contaminants underscore the need for continued investment to realise the human rights to water and sanitation.

Reflection of UVC wavelengths from common materials during surface UV disinfection: Assessment of human UV exposure and ozone generation.

The COVID-19 pandemic has promoted interest in using devices emitting ultraviolet-C (UVC) irradiation (200-280 nm) for surface disinfection to reduce pathogen transmission, especially in occupied public spaces. While UVC devices have been shown to be highly effective against various pathogens, there are safety concerns when using conventional UVC devices for surface disinfection, including human exposure of reflected UVC irradiation and ozone generation. Emerging Far UVC devices (emitting at 200-230 nm), like the krypton chloride (KrCl*) excimer, have the potential to be safely applied in occupied spaces due to their minimal adverse effects on skin and eyes.

Field Study and Evaluation of KrCl* Far UV-C Device Capability for Inactivation of Phi6 Bacteriophage.

"Far UV-C" is an effective disinfection method that can be deployed in occupied areas. Commercially available Krypton Chloride (KrCl*) excimer lamps filtered to emit at 222 nm are effective in disinfecting pathogens and safe for human exposure up to an allowable threshold exposure, which is much longer than for conventional UV lamps emitting at 254 nm. Laboratory and controlled field testing of a filtered KrCl* excimer lamp for disinfection of a virus suspended in a thin film aqueous solution in an occupied office setting was conducted.

Commercial toilets emit energetic and rapidly spreading aerosol plumes.

Aerosols can transmit infectious diseases including SARS-CoV-2, influenza and norovirus. Flushed toilets emit aerosols that spread pathogens contained in feces, but little is known about the spatiotemporal evolution of these plumes or the velocity fields that transport them. Using laser light to illuminate ejected aerosols we quantify the kinematics of plumes emanating from a commercial flushometer-type toilet, and use the motion of aerosol particles to compute velocity fields of the associated flow.

Improving the Reliability of Water Service Delivery in Rural Kenya through Professionalized Maintenance: A System Dynamics Perspective.

Reliable water service delivery continues to be a complex global issue that is particularly challenging in rural communities. Despite billions of dollars of infrastructure interventions, sustainable water services remain out of reach for millions of people. Professionalized maintenance services have emerged as a service provision strategy to supplement the community-based rural water management approach.

UV Inactivation of Common Pathogens and Surrogates Under 222 nm Irradiation from KrCl* Excimer Lamps.

Germicidal ultraviolet (UV) devices have been widely used for pathogen disinfection in water, air, and on food and surfaces. Emerging UV technologies, like the krypton chloride (KrCl*) excimer emitting at 222 nm, are rapidly gaining popularity due to their minimal adverse effects on skin and eyes compared with conventional UV lamps emitting at 254 nm, opening opportunities for UV disinfection in occupied public spaces. In this study, inactivation of seven bacteria and five viruses, including waterborne, foodborne and respiratory pathogens, was determined in a thin-film aqueous solution using a filtered KrCl* excimer emitting primarily at 222 nm.

Field study of early implementation of UV sources and their relative effectiveness for public health and safety.

The emergence of COVID-19 and its corresponding public health burden has prompted industries to rapidly implement traditional and novel control strategies to mitigate the likelihood of SARS-CoV-2 transmission, generating a surge of interest and application of ultraviolet germicidal irradiation (UVGI) sources as disinfection systems. With this increased attention the need to evaluate the efficacy and safety of these types of devices is paramount. A field study of the early implementation of UVGI devices was conducted at the Space Needle located in Seattle, Washington.

UV inactivation of sewage isolated human adenovirus.

Adenoviruses are known to be one of the most resistant viruses to UV disinfection. This study determined the inactivation kinetics of adenovirus freshly isolated from sewage samples, and compared the results with reference adenovirus stocks grown in the laboratory. Human adenoviruses were isolated from sewage samples using the HEK 293 cell line.

Inactivation of biofilm-bound bacterial cells using irradiation across UVC wavelengths.

Opportunistic pathogens (OPs), such as Pseudomonas spp., Legionella spp., and mycobacteria, have been detected in biofilms in drinking water distribution systems and water storage tanks and pose potential risks to finished drinking water quality and safety.

Pathways to consumer demand and payment for professional rural water infrastructure maintenance across low-income contexts.

Systems for regular, preventive maintenance of infrastructure are needed to ensure safe water access globally. Emerging and growing across rural sub-Saharan Africa, professionalized maintenance arrangements feature legal, regulated service providers who maintain infrastructure in exchange for consumer payment through contracts. However, little is understood about the conditions that enable service providers to retain consumer contracts, an important component of their sustainability that indicates consistent demand and payment.

Pathways for collaboratively strengthening water and sanitation systems.

Collaborative approaches are seen as a promising way to strengthen Water, Sanitation, and Hygiene (WASH) service delivery systems when challenges exceed the mandates and capabilities of any single entity. While collaborative approaches are well studied in high-income country contexts, current understanding of their application to international development contexts is limited. This paper uses fuzzy-set Qualitative Comparative Analysis to assess what conditions and pathways drove or impeded progress within eleven collaborative approaches for WASH service delivery in Eastern Africa.

UV Inactivation of SARS-CoV-2 across the UVC Spectrum: KrCl* Excimer, Mercury-Vapor, and Light-Emitting-Diode (LED) Sources.

Effective disinfection technology to combat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can help reduce viral transmission during the ongoing COVID-19 global pandemic and in the future. UV devices emitting UVC irradiation (200 to 280 nm) have proven to be effective for virus disinfection, but limited information is available for SARS-CoV-2 due to the safety requirements of testing, which is limited to biosafety level 3 (BSL3) laboratories. In this study, inactivation of SARS-CoV-2 in thin-film buffered aqueous solution (pH 7.

Household Water, Sanitation, and Hygiene Practices Impact Pathogen Exposure in Remote, Rural, Unpiped Communities.

Household water, sanitation and hygiene (WASH) practices in remote, rural, and unpiped communities are likely to impact exposure to pathogens beyond the fecal-oral transmission routes that are typically prioritized in WASH interventions. We studied 43 homes in two remote, rural, unpiped communities in Alaska to evaluate seasonal water haul, water sources, water quality, and water reuse, as well as greywater and human waste disposal over 1 year. Hauled quantities of water reportedly ranged from 3.

Inactivation of Coronaviruses and Phage Phi6 from Irradiation across UVC Wavelengths.

Ultraviolet (UV) devices emitting UVC irradiation (200-280 nm) have proven to be effective for virus disinfection, especially on surfaces and in air, due to their rapid effectiveness and limited to no material corrosion. Numerous studies of UV-induced inactivation focused on nonenveloped viruses. Little is known about UVC action on enveloped viruses across UVC wavelengths.

Aerobic biological degradation of organic matter and fracturing fluid additives in high salinity hydraulic fracturing wastewaters.

Reuse of hydraulic fracturing wastewaters depends on effective tailored treatment to prepare the water for the intended end use. Aerobic biological treatment of hydraulic fracturing produced water was examined to degrade dissolved organic carbon (DOC) and polyethylene glycols (PEGs). Biological treatment experiments of three produced water samples with DOC concentrations ranging from 22 to 420 mg/L and total dissolved solids (TDS) levels ranging from 26 to 157 g/L were conducted in 48-240 h batches.

Desalting and Concentration of Common Hydraulic Fracturing Fluid Additives and their Metabolites with Solid-Phase Extraction.

This work describes the development of a solid-phase extraction method capable of detecting common fracturing fluid additives in flowback and produced water with mass spectrometry. Dissolved organic carbon (DOC) was used as a bulk measurement to investigate the retentive capacity of seven sorbents and to determine a loading volume. Conductivity was used to determine rinse volume.