Examinando por Autor "McGuigan, Kevin G."

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Evaluation of microplastics release from solar water disinfection poly(ethylene terephthalate) and polypropylene containers
(Elsevier, 2023) Álvarez-Fernández, Carmen; Matikainen, Elina; McGuigan, Kevin G.; Andrade, Jose M.; Marugán, Javier
Public health concern associated with the ingestion of microplastics (MPs) released from water packaging materials is increasing. The use of plastic materials for solar disinfection (SODIS) containers has also raised concerns in the SODIS community due to the lack of studies evaluating the presence of MPs in the treated water. In this work, the migration of MPs from poly(ethylene terephthalate, PET) bottles and polypropylene (PP) translucent and transparent jerrycan containers (TJC) into water under natural weathering was investigated using micro-reflectance Fourier Transform Infrared Spectroscopy (µ-FTIR). Containers exposed to sunlight for three months became photodegraded, releasing micro-sized fragments identified as PET, PP and high-density polyethylene (HDPE, from the screw-caps), although with varying degrees of weathering. It is noteworthy that the presence of a clarifying additive in PP formulation did not seem to impact the release of MPs from the containers. The study showed that PP TJC containers released more MPs than PET bottles. Finally, the size of MPs was measured to determine their fate upon ingestion and highlights the need for further studies to understand the safety of these plastic containers for SODIS.
Predicting the bactericidal efficacy of solar disinfection (SODIS): from kinetic modeling of in vitro tests towards the in silico forecast of E. coli inactivation
(Elsevier, 2022-01-01) Samoili, Sofia; Farinelli, Giulio; Moreno-SanSegundo, José Ángel; McGuigan, Kevin G.; Marugán, Javier; Pulgarín, César; Giannakis, Stefanos
In this study, the possibility of predicting the efficacy of Solar water disinfection (SODIS) for the removal of bacterial pathogens was assessed by the development of a three-level plan: firstly, systematic E. coli inactivation was performed (in vitro) in Lake Geneva water, under otherwise controlled conditions of water temperature (20–50 °C), sunlight intensity (0–1200 W/m2), presence of natural dissolved organic matter (DOM, 0–6 mg/L) and turbidity (0–50 NTU). As a second step a kinetic evaluation led to the selection of the most relevant parameters to be included in a novel static and dynamic model theoretical formulation. The static and dynamic models reliably described the experimental findings (bacterial inactivation under various climatic conditions) and were considered as equally eligible candidates for disinfection modeling. The final step considered ambient temperature, incident radiation and cloud-cover data to forecast (in silico) SODIS efficacy in Africa as a case study. The simulation results were compared with the experimental data and indicated that most African regions are suitable for SODIS processes, but there are areas of risk correlated with climatological conditions (cloud-cover and temperature). The results of this study could be applied for regional in decision-making strategies for application of SODIS or in the search for viable alternatives to SODIS in cases where it is deemed unsuitable.
SODIS potential: A novel parameter to assess the suitability of solar water disinfection worldwide
(Elsevier, 2021) Moreno-SanSegundo, José; Giannakis, Stefanos; Samoili, Sofia; Farinelli, Giulio; McGuigan, Kevin G.; Pulgarín, César; Marugán, Javier
This paper studies the worldwide applicability of solar water disinfection (SODIS) technology through a novel parameter: the SODIS potential. This parameter is defined as the inverse ratio between the required exposure time to achieve a four log disinfection of E. coli and the six hours recommended by the standard SODIS protocol. The E. coli inactivation kinetics was predicted by fitting the results under different temperature and incident radiation to a semi-empirical inactivation model, including a synergy term between bacterial stress sources (light/heat). To estimate the SODIS potential, a solar calculator was developed based on the Sun's position, atmospheric extinction, cloud-cover, and elevation. The time-varying total incident radiation available at any location worldwide was estimated for each day along the year during sunlight hours. The time-varying temperature was also estimated from minimum and maximum values, introducing its dynamic variation along with the solar exposure of the water. Both incident radiation and temperature values are input into the kinetic model to estimate the disinfection rate. Based on these values, the number of batch disinfections that can reach the goal of 99.99% bacterial elimination in 1 day and the minimum daily time required to achieve this goal is computed; the latter is finally transformed to the SODIS potential. The results of the study, illustrated as contours indicating the SODIS potential and other relevant indicators overlayed on a world map, confirm that latitude has a significant contribution to the SODIS potential, with the highest values close to the equator. However, the results also highlight the importance of temperature and cloud-cover, with critical differences between equal latitude regions.
Weathering of plastic SODIS containers and the impact of ageing on their lifetime and disinfection efficacy
(Elsevier, 2022) García-Gil, Ángela; Molina-Ramírez, María Dolores; García-Muñoz, Rafael A.; Marasini, Ramesh; Buck, Lyndon; McGuigan, Kevin G.; Marugán, Javier
This work aims to study the ageing of plastic materials suitable for manufacturing solar water disinfection (SODIS) containers, such as PET, polymethylmethacrylate (PMMA), and polypropylene (PP) with and without UV-stabiliser. The evolution of mechanical and optical properties, and disinfection rates were studied over different weathering periods. PMMA and PP with a 1% content by weight of UV-stabiliser were shown to be excellent candidate materials for manufacturing SODIS devices, since they presented stable optical and mechanical properties, and both transmit UVB radiation. Since PMMA is a UV resistant but fragile, easily scratched material with a lifetime above one year, it should be selected for static SODIS devices, while PP with 1% of UV-stabiliser should be chosen for portable devices because of its great resistance and elasticity for up to nine months of solar exposure. Both materials were considered profitable on the basis of their lifetime/costs ratio. PET showed great mechanical properties for one year but, in contrast, suffered of a deterioration of its optical properties and disinfection rates. PP without UV-stabilisers suffered a dramatic degradation after a very short exposure of 2 months. Finally, a kinetic model that considers the radiation spectral distribution (thus, the transmittance spectra of the plastics as a function of the ageing time) is proposed to estimate the required solar exposure time to achieve water disinfection for the proposed plastic SODIS containers. A good agreement between predicted and experimental data was achieved, especially for containers manufactured with PET and both PPs (errors below 25%).