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Access to safe drinking water is crucial for human well-being, but the lack of this resource represents a significant global challenge. Consumption of contaminated water greatly increases the disease risk, making water disinfection essential to eliminate pathogenic microorganisms. Ultraviolet (UV) light-emitting diode (LED)-based systems emerge as an up- and-coming option to address this issue. These semiconductor devices emit light in the ultraviolet range and present a design and materials that allow efficient applications in disinfection and other fields, standing out for their environmental friendliness and overcoming the limitations associated with mercury lamps. This research uses different wavelengths and reactors for UV disinfection to evaluate the inactivation efficiency of various microorganisms, including indicator bacteria, fungal spores, cyanobacteria, and microalgae. Significant challenges are addressed, such as variability in bacterial response and resistance of emerging microorganisms. In addition, the possibility of reactivation of microorganisms after treatment is investigated. This comprehensive approach contributes to understanding the versatility of UV-LED technology in water disinfection. It promotes compliance with quality standards, public health preservation, and sustainable water treatment innovation.

Ultraviolet disinfection has been extensively studied in recent years, especially in bacteria; however, there are still insufficient studies in fungal spores. Moreover, most studies use static batch reactors instead of continuous flow reactors, which are used mainly at the industrial scale. In the present work, the inactivation and reactivation characteristics of two species of filamentous fungi were studied using a single-pass flow-through UV-C reactor (FTR). For this purpose, Aspergillus niger and Penicillium sp. spores were suspended in water and circulated through the reactor at different UV-C doses. The effects on inactivation and reactivation after 24 in either light or dark conditions were studied. The two fungal strains studied show different UV-C treatment resistance and damage repair capacity. With the experimented FTR system, an inactivation efficiency of up to 2 log units (99% removal) was achieved with doses of 220.1 ± 24.3 (Formula presented.) in the case of Aspergillus niger and 123.8 ± 6.3 (Formula presented.) in the case of Penicillium sp. The effect of dark repair is negligible, while the photoreactivation process is relevant in the case of Penicillium sp., since D2 increased by 53.8% just after UV-C exposure due to photoreactivation. In general, A. niger is more UV-C resistant than Penicillium sp.; however, the latter has a greater capacity to photoreactivate. Copyright © 2023 Duque-Sarango, Delgado-Armijos, Romero-Martínez and Pinos-Vélez.

In certain countries where fresh water is in short supply, the effluents from wastewater treatment plants are being recycled for other uses. For quality assurance, tertiary disinfection treatments are required. This study aims to evaluate the inactivating efficacy with an ultraviolet (UV) system on fecal bacteria from effluents of urban wastewater treatment facilities and the post-treatment influence of the environmental illumination. The effect from different UV doses was determined for native and standardized lyophilized strains of Escherichia coli right after the irradiation as well as after 24 h of incubation under light or dark conditions. To achieve 3 log-reductions of the initial bacterial concentration, a UV dose of approximately 12 mJ cm−2 is needed for E. coli ATCC 8739 and native E. coli. However, there is a risk of the reactivation of 0.19% and 1.54% of the inactivated organisms, respectively, if the treated organisms are stored in an illuminated environment. This suggests that the post-treatment circumstances affect the treatment success; storing the treated water under an illuminated environment may pose a risk even if an effective inactivation was achieved during the irradiation.

The consumption of batteries and cooking oil have been increasing. Most used batteries are disposed of incorrectly, leading to health and environmental problems because of their composition. In a similar form, cooking oil, once used, is often released by the discharge reaching the wastewater, polluting soil, and water, which affects its treatment. In Ecuador, these environmental passives are recollected and stored without further treatment, which is a temporary and unsustainable solution. To address this issue, the circular economy concept has gained increasing attention. In this study, zinc oxide was prepared from discarded batteries using the hydrometallurgical method to use as a catalyst; it achieved 98.49% purity and 56.20% yield and 20.92% of particles presented a particle size of 1–10 nm. Furthermore, the catalyst morphology was investigated in an SEM, which showed that particle size ranged from 155.69 up to 490.15 nm and spherical shapes. Due to its characteristics, the obtained catalyst can be used in the industry instead of the zinc oxide obtained by mining processes. These processes are known to produce heavy contamination in the ecosystems and human health. Additionally, a zinc oxide lifecycle in the environment was analyzed through a material flow analysis (MFA), taking into consideration two paths, one assuming the disposal of used batteries and the other assuming the recycling of zinc. Biodiesel was produced with a heterogeneous catalyst. This took place with a transesterification reaction with used cooking oil, ethanol, and zinc oxide (ZnO) as catalysts. The biodiesel obtained had the following characteristics: 37.55 kJg−1 of heating power, 0.892 gcm−3 of density, 4.189 mm2/s of viscosity, 0.001% of water content, and a 70.91% yield. Furthermore, the energy consumption in biodiesel production was quantified, giving a total of 37.15 kWh. This kind of initiative prevents that waste from becoming environmental pollutants and potential health risks by giv

Treatment with ultraviolet (UV) light is a common option for inactivating waterborne organisms. The mercury vapor lamps conventionally used as a source of UV-C light for water disinfection are eventually replaced by light emitter diodes (LEDs) in the middle term due to their higher efficiency and lack of hazardous materials. Nonetheless, biological mechanisms for repairing UV damage caused by the UV treatment are some of its significant undesirable features. The objective of this study is to evaluate and compare the UV-resistance and the reactivation degree in different strains of E. coli and E. faecalis treated with a flow-through reactor equipped with LEDs with an emission range between 265 and 285 nm. The treated organisms were subjected to various illumination regimes after the UV irradiation. The results obtained indicated that intraspecific differences between the strains of E. coli were greater than the interspecific differences with respect to E. faecalis in terms of UV-resistance and repairing potential. The UV doses necessary to achieve four log-reductions ranged from 10.2 to 16.3 mJ cm−2 for E. coli and from 11.1 to 11.4 for mJ cm−2 for E. faecalis. Dark repair was not observed within 24 h after the UV irradiation whereas the degree of photorepair depended on both the bacteria strain and the applied UV dose. The exposure of the irradiated organisms to an illuminated environment entailed and increasing between the 18 % and the 160 % of the UV dose required to achieve four log-reductions.

The present work applied the ASM1 simulation model for the wastewater treatment system of Guangarcucho plant (G-WWTP) in the city of Cuenca. The main objective was to generate conclusions about parameters that determine the quality of the effluent, and to have a first approximation of the operating processes in the plant. In order to achieve this, a work routine was developed with the WEST software, data on pollutant concentration and flow rates from a year of daily records (year 2018–2019) was taken at the entrance of the Ucubamba current wastewater treatment plant (U-WWTP), which were provided by ETAPA-EP, while kinetic parameters were taken from those used for designing G-WWTP plant. Steady-state simulations were performed to later analyze dynamic-state simulations. The topological configuration was structured by biological reactors, a dissolved oxygen control model, a secondary settlers model, combiners and flow dividers, among the main elements. In addition, a basic sensitivity analysis was performed on variables that can be manipulated at the macro level in the plant: dissolved oxygen concentration (DO) and internal sludge recirculation (Qlodos). It was found that internal sludge recirculation influences positively on the effluent quality, causing concentration of organic matter (BOD) and decrease of the suspended solids (TSS) to decrease, while the concentration of dissolved oxygen higher or lower than 2.5 mg/L, does not have a greater influence on the quality variation of the effluent.

The present work studied the performance of the biological treatment through a system of Rotating Biological Counters (RBC) built at the laboratory of the Universidad Politécnica Salesiana. Wastewater obtained from the Wastewater Treatment Plant of Ucubamba-Cuenca was used, the control and operation was carried out by measuring physical-chemical parameters; nitrates, nitrites, chlorine, ammonium, pH, conductivity, sedimentation, turbidity and chemical oxygen demand. Next, the kinetic model of substrate degradation was established and validation of the model was done with the data obtained in the laboratory. Finally, the experimental results were compared with the theoretical model, obtaining a comparable result between both; an experimental fit was verified with a k value (coefficient of degradation of organic matter) equal to 0,056 and with an R2 of 0.85 and 0.97 in the theoretical and experimental model respectively., El presente trabajo estudió el rendimiento del tratamiento biológico mediante un sistema de Contadores Biológicos Rotatorios (CBR) construido a nivel de laboratorio de la Universidad Politécnica Salesiana. Para ello se utilizaron aguas residuales obtenidas de la Planta de Tratamiento de Aguas Residuales de Ucubamba-Cuenca, se llevó a cabo un control y operación mediante la medición de parámetros físico químicos; nitratos, nitritos, cloro, amonio, pH, conductividad, sedimentación, turbidez y demanda química de oxígeno. Para luego establecer el modelo cinético de degradación del sustrato y validación del mismo, con los datos obtenidos en el laboratorio. Finalmente, los resultados experimentales fueron comparados con el modelo teórico, obteniéndose un resultado comparable entre ambos; se comprobó un ajuste experimental con un valor k (coeficiente de degradación de la materia orgánica) igual a 0,056 y con un R2 de 0,85 y 0,97 en el modelo teórico y experimental respectivamente.

The present article studied the electrochemical treatment in waste sludge from a Wastewater Treatment Plant (WWTP) through the operation of a pilot plant, consisting of 3 tanks or electrolytic cells, whose electrodes were copper plates and graphite at different distances; 7.5, 15 and 12 cm in the tanks A, B and C respectively, in them approximately 6800 cm3 of hydrated sludge were placed with 12% sodium chloride. When the plates were in contact with themud, they were exposed to a direct current of 12 volts, 4 samples were taken in each of the 3 tanks, which obey contact times of 1 to 4 hours. In the laboratory phase were measured: pH, conductivity, temperature, humidity, sodium hypochlorite and analyzed the reduction of the concentration of aluminum and helminth eggs after treatments. It was found that the percentage of residual aluminum is the same for any of the cells, whether it is A, B or C; however, cellB has a smaller dispersion according to the Levene statistic. A 100% removal of helminth eggs was also achieved in all trials., El presente artículo estudió el tratamiento electroquímico en fangos residuales provenientes de una Planta de Tratamiento de Aguas Residuales (PTAR) mediante la operación de una planta piloto, conformada por 3 cubas o celdas electrolíticas, cuyos electrodos fueron placas de cobre y grafito a diferentes distancias; 7.5, 15 y 12 cm en las cubas A, B y C respectivamente, en ellas se dispusieron aproximadamente 6800 cm3 de fango hidratado con cloruro de sodio al 12%. Al estar en contacto las placas con el fango se expusieron a una corriente continua de 12 voltios, se tomaron 4 muestras en cada una de las 3 cubas, que obedecen a tiempos de contacto de 1 a 4 horas. En la fase de laboratorio se midieron: pH, conductividad, temperatura, humedad, hipoclorito de sodio y se analizó la reducción de la concentración de aluminio y huevos helmintos después de los tratamientos. Se encontró que el porcentaje Al residual es igual paracualquiera de las celdas ya sea la A, B o C; sin embargo la celda B posee una menor dispersión según el estadístico de Levene. Se consiguió además una remoción del 100% de huevos de helmintos en todos los ensayos.

The present article studied the electrochemical treatment in waste sludge from a Wastewater Treatment Plant (WWTP) through the operation of a pilot plant, consisting of 3 tanks or electrolytic cells, whose electrodes were copper plates and graphite at different distances; 7.5, 15 and 12 cm in the tanks A, B and C respectively, in them approximately 6800 cm3 of hydrated sludge were placed with 12% sodium chloride. When the plates were in contact with themud, they were exposed to a direct current of 12 volts, 4 samples were taken in each of the 3 tanks, which obey contact times of 1 to 4 hours. In the laboratory phase were measured: pH, conductivity, temperature, humidity, sodium hypochlorite and analyzed the reduction of the concentration of aluminum and helminth eggs after treatments. It was found that the percentage of residual aluminum is the same for any of the cells, whether it is A, B or C; however, cellB has a smaller dispersion according to the Levene statistic. A 100% removal of helminth eggs was also achieved in all trials., El presente artículo estudió el tratamiento electroquímico en fangos residuales provenientes de una Planta de Tratamiento de Aguas Residuales (PTAR) mediante la operación de una planta piloto, conformada por 3 cubas o celdas electrolíticas, cuyos electrodos fueron placas de cobre y grafito a diferentes distancias; 7.5, 15 y 12 cm en las cubas A, B y C respectivamente, en ellas se dispusieron aproximadamente 6800 cm3 de fango hidratado con cloruro de sodio al 12%. Al estar en contacto las placas con el fango se expusieron a una corriente continua de 12 voltios, se tomaron 4 muestras en cada una de las 3 cubas, que obedecen a tiempos de contacto de 1 a 4 horas. En la fase de laboratorio se midieron: pH, conductividad, temperatura, humedad, hipoclorito de sodio y se analizó la reducción de la concentración de aluminio y huevos helmintos después de los tratamientos. Se encontró que el porcentaje Al residual es igual paracualquiera de las celdas ya sea la A, B o C; sin embargo la celda B posee una menor dispersión según el estadístico de Levene. Se consiguió además una remoción del 100% de huevos de helmintos en todos los ensayos.