Examinando por Autor "Marugán, Javier"

Mostrando 1 - 20 de 43

A comprehensive study of the synthesis, characterization and activity of TiO2 and mixed TiO2/SiO2 photocatalysts
(ELSEVIER, 2006) Aguado, José; van Grieken, Rafael; López-Muñoz, María-José; Marugán, Javier
The use of titania-silica materials in photocatalytic processes has been proposed as an alternative to the conventional TiO2 catalysts, in order to facilitate the separation of the solids after the reaction. However, despite the large number of works in this field, up to date it is not totally clarified the mechanism governing the photocatalytic activity of the mixed TiO2/SiO2 oxides. In the present work several titania-silica materials have been prepared through a sol-gel method controlling the main variables to obtain materials with different textural properties, degree of titanium incorporation and dispersion of such species, and crystallinity of titanium dioxide. Characterization of the samples and correlation with their activity for the photocatalytic oxidation of cyanide has permitted to determine that the main factors conditioning the photoactivity of these materials are: i) textural properties and accessibility of the titania surface, ii) formation of anatase nanocrystals of suitable size and band gap energy, and iii) quality of the titania crystal network, improved by the use of a hydrothermal crystallization procedure.
A model to predict the kinetics of direct (endogenous) virus inactivation by sunlight at different latitudes and seasons, based on the equivalent monochromatic wavelength approach
(Elsevier, 2021) García-Gil, Ángela; Marugán, Javier; Vione, Davide
Sunlight plays an important role in the inactivation of pathogenic microorganisms such as bacteria and viruses in water. Here we present a model that is able to predict the kinetics of direct virus inactivation (i.e. inactivation triggered by sunlight absorption by the virion, without the role played by photochemically produced reactive intermediates generated by water-dissolved photosensitizers) on a global scale (from 60 °S to 60 °N latitude) and for the different months of the year. The model is based on the equivalent monochromatic wavelength (EMW) approach that was introduced recently, and which largely simplifies complex polychromatic calculations by approximating them with a monochromatic equation at the proper wavelength, the EMW. The EMW equation was initially established for mid-July conditions at a mid-latitude, and was then extended to different seasons and to the latitude belt where the day-night cycle is always observed throughout the year. By so doing, the first-order rate constant of direct virus photoinactivation can be predicted on a global scale, with the use of a relatively simple equation plus tables of pre-calculated input data, as a function of latitude, month, and key water parameters. The model was here applied to the virus organism phiX174, a somatic phage that is often used as proxy for pathogenic viruses undergoing fast direct inactivation, and for which a wide array of published inactivation data is available. Model predictions are validated by comparison with field data of inactivation of somatic phages by sunlight.
A review on LED technology in water photodisinfection
(Elsevier, 2023) Martín-Sómer, Miguel; Pablos, Cristina; Adán, Cristina; Grieken, Rafael van; Marugán, Javier
The increase in efficiency achieved by UV LED devices has led to a compelling increase in research reports on UV LED water treatment for consumption in the past few years. This paper presents an in-depth review based on recent studies on the suitability and performance of UV LED-driven processes for water disinfection. The effect of different UV wavelengths and their combinations was analysed for the inactivation of various microorganisms and the inhibition of repair mechanisms. Whereas 265 nm UVC LED present a higher DNA damaging potential, 280 nm radiation is reported to repress photoreactivation and dark repair. No synergistic effects have been proved to exist when coupling UVB + UVC whereas sequential UVA-UVC radiation seemed to enhance inactivation. Benefits of pulsed over continuous radiation in terms of germicidal effects and energy consumption were also analysed, but with inconclusive results. However, pulsed radiation may be promising for improving thermal management. As a challenge, the use of UV LED sources introduces significant inhomogeneities in the light distribution, pushing for the development of adequate simulation methods to ensure that the minimum target dose required for the target microbes is achieved. Concerning energy consumption, selecting the optimal wavelength of the UV LED needs a compromise between the quantum efficiency of the process and the electricity-to-photon conversion. The expected development of the UV LED industry in the next few years points to UVC LED as a promising technology for water disinfection at a large scale that could be competitive in the market in the near future.
Analogies and differences between photocatalytic oxidation of chemicals and photocatalytic inactivation of microorganisms
(ELSEVIER, 2010) Marugán, Javier; van Grieken, Rafael; Pablos, Cristina; Sordo, Carlos
This study reports the analogies and differences found when comparing TiO2 photocatalytic treatment for chemical oxidation and microorganisms inactivation, using methylene blue and Escherichia coli as references, respectively. In both processes the activation is based on the same physicochemical phenomena and consequently a good correlation between them is observed when analyzing the effect of operational variables such as catalyst concentration or incident radiation flux, both factors influencing common stages such radiation absorption and generation of reactive oxygen species. However, different microbiological aspects (osmotic stress, repairing mechanism, regrowth, bacterial adhesion to the titania surface, etc) makes disinfection kinetics significantly more complex than the first-order profiles usually observed for the oxidation of chemical pollutants. Moreover, bacterial inactivation reactions are found to be extremely sensitive to the composition of water and modifications of the catalysts in comparison with the decolorization of the dye solutions, showing opposite behaviors to the presence of chlorides, incorporation of silver to the catalysts or the use of different types of immobilized TiO2 systems. Therefore, the activity observed for the photocatalytic oxidation of organics can not be always extrapolated to photocatalytic disinfection processes.
Comparative evaluation of acute toxicity by Vibrio fischeri and fern spore based bioassays in the follow-up of toxic chemicals degradation by photocatalysis
(ELSEVIER, 2012) Marugán, Javier; Bru, David; Pablos, Cristina; Catalá, Myriam
The development of efficient bioassays is a necessary step for cost-effective environmental monitoring and evaluation of novel decontamination technologies. Marine Vibrio fischeri kits have demonstrated to be extremely sensitive but lack of ecological relevance, especially when assessing impacts on freshwater higher organisms. A novel riparian fern spore microbioassay could merge higher ecological relevance and reduced costs. The aim of this work is the comparative evaluation of the Vibrio fischeri and fern spore bioassays for the follow up of detoxification processes of 30 water contaminated with cyanide and phenol by advanced oxidation technologies, using heterogeneous photocatalysis as example. In both cases, EC50 values differed significantly for V.fisheri commercial kit, V.fisheri lab cultures and Polystichum setiferum fern spores (1.9, 16 and 101 mg cyanide L-1 and 27.0, 49.3 and 1440 mg phenol L-1, respectively). Whereas V.fischeri bioassays are extremely sensitive and dilution series must be prepared, toxicant solutions can be directly applied to spores. Spore microbioassay was also useful in the follow up of photoxidation processes of cyanide and phenol, also reflecting the formation of intermediate degradation by-products even more toxic than phenol. We conclude that this new microbioassay is a promising cost-effective tool for the follow up of decontamination processes.
Comparing the efficiency of solar water treatment: Photovoltaic-LED vs compound parabolic collector photoreactors
(Elsevier, 2023) Martín-Sómer, Miguel; Molina-Ramírez, María Dolores; Perez-Araujo, Maria Luisa; van Grieken, Rafael; Marugán, Javier
This work analyses how to optimise efficiency in the use of solar light for different UV-based photochemical water treatment processes. The direct use of sunlight in state-of-the-art compound parabolic collector (CPC) photoreactors is compared with the use of solar energy for electricity generation in photovoltaic (PV) power systems to feed LED lighting sources. Seven different solar processes (CPC, PV-UVA LED, PV-UVC LED, CPC+TiO2, CPC+H2O2, PV-UVA LED+TiO2 and PV–UVC LED+H2O2) were investigated, both for the oxidation of chemicals and the inactivation of bacteria. The results showed that, for the oxidation of chemicals, the best photochemical yield (in terms of the use of photons) is achieved by the PV-UVC LED+H2O2 process. However, the low electrical efficiency of current UVC LED sources makes the CPC+TiO2 process the most efficient in the use of solar light. In contrast, for bacterial inactivation, the significantly higher effectiveness of the UVC spectral range in damaging DNA makes the PV-UVC LED+H2O2 the most efficient in the use of sunlight. When costs are considered, the PV-UVA LED+TiO2 may be the most efficient process for chemical oxidation, while the PV-UVC LED+H2O2 process could be the most efficient for bacterial inactivation. These findings highlight the need to evaluate the optimal approach in reactor engineering for applications in the water-energy nexus, since the most efficient process for the use of solar light strongly depends on the electrical efficiency of the available PV and LED technology, which can be expected to be largely improved in the near future.
Comparison between the Photocatalytic inactivation of Gram-positive E. Faecalis and Gram-negative E. Coli Faecal contamination indicator microorganism
(ELSEVIER, 2010) van Grieken, Rafael; Marugán, Javier; Pablos, Cristina; Furones, Laura; López, Ainhoa
Photocatalytic inactivation of two different faecal contamination indicator microorganisms, the Gram-negative Escherichia coli and the Gram-positive Enterococcus faecalis, has been studied using TiO2 in suspension and immobilized onto the photocatalytic reactor wall. The effect of the main variables of the photocatalytic process on the disinfection efficiency in deionized water and simulated effluent of wastewater treatment plant (WTP) effluents has been analyzed. Noticeable differences were observed between both types of bacteria during photolytic experiments without TiO2 in deionized water, probably due to the higher sensibility of E. coli to the osmotic stress, which leads to a higher cell membrane permeability and consequently a lower amount of hydroxyl radical attacks required to overcome the inactivation threshold. In contrast, despite their structural differences, Gram-positive and Gram-negative bacteria seem to follow the same inactivation mechanism, showing no significant differences in the experiments carried out with TiO2 in suspension either in deionized water or in WTP simulated effluent, and similar responses to changes in the concentration of catalysts and irradiation power (both variables involved in the hydroxyl radical generation). Similar results are observed using immobilized TiO2 in deionized water. However, disinfection experiments of WTP simulated effluent using immobilized TiO2 showed much longer initial delays before the beginning of the inactivation for E. faecalis, suggesting a critical effect of the water composition of the bacteria-catalyst interaction. In any case, the irradiation time required to achieved the inactivation below the experimental bacterial detection limit is similar for both microorganisms, and experiments with mixtures of E.faecalis and E.coli in WTP simulated effluent show no significant differences. Therefore, it can be concluded that the results of photocatalytic disinfection experiments using E. coli as model bacteria could be reasonably extrapolated to other types of bacteria or bacterial mixtures.
Correlation between photoelectrochemical behaviour and photoelectrocatalytic activity and scaling-up of P25-TiO2 electrodes
(Elsevier, 2014) Pablos, Cristina; Marugán, Javier; Grieken, Rafael van; Adán, Cristina; Riquelme, Ainhoa; Palma, Jesús
The use of TiO2 electrodes may solve the two main drawbacks of photocatalytic processes: i) the necessity of recovering the catalyst and ii) the low quantum yield in the use of the radiation. This work focuses on the correlation between the photoelectrochemical properties of TiO2 electrodes and their activity for the photoelectrocatalytic oxidation of methanol. Particulate TiO2 electrodes prepared by deposition of P25-TiO2 nanoparticles on titanium (TiO2/Ti) or conductive glass support (TiO2/ITO) seem to be effective for charge carrier transference on TiO2 surface favouring the formation of ¿OH radicals and consequently, the oxidation of molecules. In contrast, thermal TiO2 electrodes prepared by annealing of titanium (Ti) present better properties for charge carrier separation as a consequence of the application of a potential bias. Despite reducing charge carrier recombination by applying an electric potential bias, the activity of thermal electrodes remains lower than that of P25-particulate electrodes. TiO2 structure of P25-particulate electrodes does not completely allow developing a potential gradient. However, their adequate TiO2 layer characteristics for charge carrier transfer lead to a reduction in charge carrier recombination making up for the lack of charge carrier separation when applying an electric potential bias. TiO2/Ti showed the highest values of activity. Therefore, the combination of the suitable TiO2 surface properties for charge carrier transfer with an adequate conductive support seems to increase the properties of the electrode for allowing charge carrier separation. The scaling-up calculations for a TiO2/ITO electrode do lead to good estimations of the activity and photocurrent of larger electrodes since this photoanode made from ITO as conductive support does not seem to be significantly affected by the applied potential bias.
Critical assessment of optical sensor parameters for the measurement of ultraviolet LED lamps
(Elsevier, 2022) Uppinakudru, Adithya Pai; Reynolds, Ken; Stanley, Simon; Pablos, Cristina; Marugán, Javier
Measurement of light output from ultraviolet (UV) light-based devices is critical to understanding the capability of the device. Optical sensors such as radiometers and dosimeters can possess different angular responses and are sensitive to many parameters in the measurement set-up. This work has been designed to quantify the effect of multiple parameters on the measurements obtained from optical sensors to provide inputs for validating measured data for ultraviolet sources. Multiple light sources operating in the ultraviolet range have been measured and a comparison between different sensors is presented. The angular response has been evaluated for each detector and compared with an ideal cosine response. Two of the six sensors studied displayed a near cosine response. A change of angle of acceptance with wavelength was observed for the ThorLabs S120VC and ILT W Optic diffuser. Due to use of artificial heating, the effect of measured intensities on the sensor as a function of temperature was seen to be insignificant but provided an understanding of how temperature of the sensor can influence measured data. Finally, the effect of ambient light and the integration time on the measured data were investigated. The effect of ambient light proved to be significant, when not considered in measurement of low light signals sources while the effect of choosing an ideal integration time has been seen to impact the measurements obtained. A measured difference of 43% was observed between a saturated and unsaturated sensor.
Critical review of technologies for the on-site treatment of hospital wastewater: From conventional to combined advanced processes
(Elsevier, 2022) Pariente, María Isabel; Segura, Yolanda; Alvarez, Silvia; Casas, J.A.; Pedro, Z.M. de; Diaz, E.; García, J.; López-Muñoz, M.J.; Marugán, Javier; Mohedano, Ángel Fernandez; Molina, Raúl; Muñoz, M.; Pablos, Cristina; Perdigón-Melón, J.A.; Petre, A.L.; Rodríguez, J.J.; Tobajas, M.; Martínez, F.
This review aims to assess different technologies for the on-site treatment of hospital wastewater (HWW) to remove pharmaceutical compounds (PhCs) as sustances of emerging concern at a bench, pilot, and full scales from 2014 to 2020. Moreover, a rough characterisation of hospital effluents is presented. The main detected PhCs are antibiotics and psychiatric drugs, with concentrations up to 1.1 mg/L. On the one hand, regarding the presented technologies, membrane bioreactors (MBRs) are a good alternative for treating HWW with PhCs removal values higher than 80% in removing analgesics, anti-inflammatories, cardiovascular drugs, and some antibiotics. Moreover, this system has been scaled up to the pilot plant scale. However, some target compounds are still present in the treated effluent, such as psychiatric and contrast media drugs and recalcitrant antibiotics (erythromycin and sulfamethoxazole). On the other hand, ozonation effectively removes antibiotics found in the HWW (>93%), and some studies are carried out at the pilot plant scale. Even though, some families, such as the X-ray contrast media, are recalcitrant to ozone. Other advanced oxidation processes (AOPs), such as Fenton-like or UV treatments, seem very effective for removing pharmaceuticals, Antibiotic Resistance Bacteria (ARBs) and Antibiotic Resistance Genes (ARGs). However, they are not implanted at pilot plant or full scale as they usually consider extra reactants such as ozone, iron, or UV-light, making the scale-up of the processes a challenging task to treat high-loading wastewater. Thus, several examples of biological wastewater treatment methods combined with AOPs have been proposed as the better strategy to treat HWW with high removal of PhCs (generally over 98%) and ARGs/ARBs (below the detection limit) and lower spending on reactants. However, it still requires further development and optimisation of the integrated processes.
Emerging micropollutant oxidation during disinfection processes using UV-C, UC-C/H2O2, UV-A/TiO2 and UV-A/TiO2/H2O2
(Elsevier, 2013) Marugán, Javier; Pablos, Cristina; Grieken, Rafael van; Serrano, Elena
Regeneration of wastewater treatment plant effluents constitutes a solution to increase the availability of water resources in arid regions. Water reuse legislation imposes an exhaustive control of the microbiological quality of water in the operation of disinfection tertiary treatments. Additionally, recent reports have paid increasing attention on emerging micropollutants with potential biological effects even at trace level concentration. This work focuses on the evaluation of several photochemical technologies as disinfection processes with the aim of simultaneously achieving bacterial inactivation and oxidation of pharmaceuticals as examples of emerging micropollutants typically present in water and widely studied in the literature. UV-C-based processes show a high efficiency to inactivate bacteria. However, the bacterial damages are reversible and only when using H2O2, bacteria reproduction is affected. Moreover, a complete elimination of pharmaceutical compounds was not achieved at the end of the inactivation process. In contrast, UV-A/TiO2 required a longer irradiation time to inactivate bacteria but pharmaceuticals were completely removed along the process. In addition, its oxidation mechanism, based on hydroxyl radicals (¿OH), leads to irreversible bacterial damages, not requiring of chemicals to avoid bacteria regrowth. For UV-A/TiO2/H2O2 process, the addition of H2O2 improved E. coli inactivation since the cell wall weakening, due to ¿OH attacks, allowed H2O2 to diffuse into the bacteria. However, a total elimination of the pharmaceuticals was not achieved during the inactivation process.
Environmental life cycle assessment of UV-C LEDs vs. mercury lamps and oxidant selection for diclofenac degradation
(Elsevier, 2024) Pizzichetti, Raffaella; Martín-Gamboa, Mario; Pablos, Cristina; Reynolds, Ken; Stanley, Simon; Dufour, Javier; Marugán, Javier
This study is the first environmental comparison between a UV-C LED lamp (emitting at 265 nm) and mercury lamps employed in a lab-scale photoreactor for water treatment purification purposes, using the removal of diclofenac as a case study. Ex-ante life cycle assessment (LCA) methodology was used as a robust method to identify hotspots and recommendations at the early stage of the UV-C LEDs technology. The functional unit was defined as “the treatment of 1 L of polluted water with 20 mg L−1 of diclofenac to achieve a 90% removal of the contaminant”, while the system boundaries include the production and the operation of the photoreactors, following a cradle-to-gate approach. Several scenarios were explored, and overall, the UV-C LED lamp shows a promising environmental performance, with less or similar potential impacts than the mercury lamps in the 16 categories selected from the Environmental Footprint (EF) method. In particular, it reveals less impact in “human toxicity non-cancer” and “resource use minerals and metals” and presents electricity as the main source of impact. Given the higher efficacy of the UV-driven advanced oxidation processes compared to the UV irradiation alone, and since no studies have previously been conducted on the sustainability of free chlorine (FC) as an oxidant in water treatment, a comparison between UV-C, UV-C/H2O2, and UV-C/FC while employing the 265 nm UV-C LED lamp was also assessed. UV-C/H2O2 was more sustainable than UV-C/FC for the same treatment time, but both led to an overall impact reduction of 35% and 30%, respectively. To increase sustainability, employing cleaner energy sources such as photovoltaic or wind energy also resulted in an 80% and 93% reduction in the “climate change” category. Overall, this study demonstrates that using UV-C LEDs and the selected oxidants for water purification is beneficial and encourages the scale-up of the system.
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.
Evaluation of new photochemical systems for water disinfection by the integration of particle tracking into kinetic models for microbial inactivation
(Elsevier, 2023) Casado, Cintia; Yunta, Verónica; Marugán, Javier
This work presents the development of a novel methodology for the simulation of photochemical processes for water disinfection using computational fluid dynamics (CFD). A new approach was implemented to calculate and visualise the disinfection performance as the microorganisms move along the photoreactor. Hydrodynamics and microorganism’s statistical trajectories were computed using the discrete phase model, which also provides the distribution of microbial residence times. The distribution of radiation in the reactor was calculated using the discrete ordinate method. The local values of incident radiation were integrated over each statistical trajectory path to get the accumulated dose received for each microbial particle. The coupling in situ of the cumulative radiation dose with the inactivation kinetics allows monitoring of the disinfection process concurrently with the particle tracking. This methodology introduces significant advantages over the traditional estimation of the microorganism inactivation sequentially after calculating the dose histograms estimated from the statistical trajectories. The developed tool enables evaluating the photoreactor efficiency in each reactor position, a useful capability for optimising and scaling up complex geometries. It also allows the easy, intuitive visualisation of microbial inactivation trajectories, improving the understanding of the influence of the reactor features on the disinfection process. Application of this computational approach to two different photoreactor geometries using a virus as a representative target microbe is presented.
Evaluation of the uniformity of UVA LED illumination on flat surfaces: Discrete ordinate method, single axis, and surface scanning radiometry
(Elsevier, 2023) Reddick, Conor; Casado, Cintia; Reynolds, Ken; Stanley, Simon; Pablos, Cristina; Marugán, Javier
Uniform illumination from UVA LED lamps is a crucial design characteristic for a range of industries including photocatalytic applications. In this work, radiometry and the discrete ordinate method (DOM) are used to determine the ideal target surface size and working distance from a UVA LED lamp for highly uniform illumination. Horizontal incident radiation and full surface incident radiation measurements were conducted using a scanning radiometry technique. It is shown that horizontal incident and full surface incident radiation measurements show good agreement for uniformity measurements over a range of working distances, with maximum uniformity (2.6% and 3.6% standard deviation respectively) over the measured range found at 15 mm working distance. DOM simulation results showed good agreement with radiometry for power and incident radiation measurements, whilst indicating a maximum uniformity at 20 mm working distance. These results demonstrate that DOM simulations can be used as a fast, low cost, and reliable indication of surface uniformity, peak surface irradiance, and power measurements in the design of UV lamps for industrial and academic applications.
Experimental evaluation and energy analysis of a two-step water splitting thermochemical cycle for solar hydrogen production based on La0.8Sr0.2CoO3-δ perovskite
(Elsevier, 2022) Orfila, María; Linares, María; Pérez, Antonio; Barras García, Inés; Molina Gil, Raúl; Marugán, Javier; Botas, Juan Ángel; Sanz, Raúl
A study of the hydrogen production by thermochemical water splitting with a commercial perovskite La0.8Sr0.2CoO3-d(denoted as LSC) under different temperature conditions is presented. The experiments revealed that high operational temperatures for the thermal reduction step (>1000 C) implied a decrease in the hydrogen production with each consecutive cycle due to the formation of segregated phases of Co3O4. On the other hand, the experiments at lower thermal reduction operational temperatures indicated that the material had a stable behaviour with a hydrogen production of 15.8 cm3 STP/gmaterial$cycle during 20 consecutive cycles at 1000 C, being negligible at 800 C. This results comparable or even higher than the maximum values reported in literature for other perovskites (9.80 e10.50 STP/gmaterial$cycle), but at considerable lower temperatures in the reduction step of the thermochemical cycle for the water splitting (1000 vs 1300e1400 C). The LSC keeps the perovskite type structure after each thermochemical cycle, ensuring a stable and constant H2 production. An energy and exergy evaluation of the cycle led to values of solar to fuel efficiency and exergy efficiency of 0.67 and 0.36 (as a percentage of 1), respectively, which are higher than those reported for other metal oxides redox pairs commonly found in the literature, being the reduction temperature remarkably lower. These facts point out to the LSC perovskite as a promising material for full-scale applications of solar hydrogen production with good cyclability and compatible with current concentrating solar power technology.
Global modeling of lake-water indirect photochemistry based on the equivalent monochromatic wavelength approximation: The case of the triplet states of chromophoric dissolved organic matter
(Elsevier, 2023) Carena, Luca; García-Gil, Ángela; Marugán, Javier; Vione, Davide
Chromophoric dissolved organic matter (CDOM) plays key role as photosensitizer in sunlit surface-water environments, and it is deeply involved in the photodegradation of contaminants. It has recently been shown that sunlight absorption by CDOM can be conveniently approximated based on its monochromatic absorption at 560 nm. Here we show that such an approximation allows for the assessment of CDOM photoreactions on a wide global scale and, particularly, in the latitude belt between 60◦S and 60◦N. Global lake databases are currently incomplete as far as water chemistry is concerned, but estimates of the content of organic matter are available. With such data it is possible to assess global steady-state concentrations of CDOM triplet states ( 3 CDOM*), which are predicted to reach particularly high values at Nordic latitudes during summer, due to a combination of high sunlight irradiance and elevated content of organic matter. For the first time to our knowledge, we are able to model an indirect photochemistry process in inland waters around the globe. Implications are discussed for the phototransformation of a contaminant that is mainly degraded by reaction with 3 CDOM* (clofibric acid, lipid regulator metabolite), and for the formation of known products on a wide geographic scale.
Growth and prevalence of antibiotic-resistant bacteria in microplastic biofilm from wastewater treatment plant effluents
(Elsevier, 2022) Perveen, Shabila; Pablos, Cristina; Reynolds, Ken; Stanley, Simon; Marugán, Javier
It is accepted that Microplastic (MP) biofilms accumulates antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARGs) in water. ARB/ARGs and MPs are emerging pollutants of concern due to various associated health risks. The objective of this study was to 1) investigate the ARB community in a pilot-scale wastewater treatment plant (WWTP) effluent, 2) to study and visualize the ARB/ARGs in MP biofilm grown in WWTP effluent and tap water, and 3) to analyze microplastic adherent ARB/ARGs in the biofilm and planktonic ARB/ARGs in the filtrate under controlled conditions. Results indicated the dominance of Pseudomonas, Aeromonas, and Bacillus among isolated ARB in WWTP effluent. Representative resistance strains were incubated in 300 mL water containing commercial polystyrene beads of 300550 μm diameter (MP) in a series of batch experiments. Microbiological, molecular, and microscopic analyses were performed by enumeration, 16srRNA, real-time polymerase chain reaction (qPCR), and Field Emission-Scanning Electron Microscopy (FEG-SEM) techniques. The analyzed viable ARB indicated an increasing trend in MP biofilms between days 3 and 5. It further decreased on days 7 and 9. The prevalence of ARB in the filtrate and MP biofilm varied as a function of time and TOC level, while no significant impacts were observed for minor temperature variation, low antibiotic pressure, and increased MP mass with few exceptions. Relative abundance of ARGs (vanA, sul1) and integron integrase gene (intl1) in MP biofilm were significantly different across different TOC levels, time, and antibiotic pressure. ARGs and intl1 were detected in the MP biofilm in tap water and WWTP effluent on day 30.
High-performance low-cost solar collectors for water treatment fabricated with recycled materials, open-source hardware and 3d-printing technologies
(Elsevier, 2021) Martín-Sómer, Miguel; Moreno-SanSegundo, Jose; Álvarez-Fernández, Carmen; van Grieken, Rafael; Marugán, Javier
Solar technologies constitute an excellent alternative for water treatment in low-income countries where the poverty of a large part of the population hinders their access to safe water. From a technical point of view, the use of compound parabolic collectors (CPC) has been consolidated in the last decades. However, the relatively high cost of tooling conventional manufacturing processes for these collectors makes them difficult to afford in the most impoverished regions. This work presents the development of low-cost CPC and parabolic through solar collectors (PTC) by 3D printing of the structure and the use of recycled reflective materials. Besides, open-source hardware has been used to control system operation, including a supplementary UV LED system to compensate for the operation under low solar irradiance. Regarding the tested reflective materials, an optimum is obtained using an aluminium adhesive sheet that leads to an efficiency of 80% compared to a commercial CPC made of high-quality anodised aluminium, being the cost 20 times lower. On the other hand, incorporating a low-cost solar tracking system in a printed PTC reactor could lead to efficiencies up to 300% compared to the commercial CPC, while the cost was 4.5 times lower. Finally, the LED compensation system was successfully validated, allowing the operation with a constant treatment capacity during operation in cloudy conditions. In conclusion, the developed collectors are high-performance solar water treatment systems with a significantly lower investment cost, making them affordable worldwide.
Hydrogen production by isothermal thermochemical cycles using La0.8Ca0.2MeO3±δ (Me = Co, Ni, Fe and Cu) perovskites
(Elsevier, 2023) Pérez, Alejandro; Orfila, María; Linares, María; Sanz, Raúl; Marugán, Javier; Molina, Raúl; Botas, Juan A.
Solar-driven thermochemical water splitting has the potential to transform concentrated solar energy into green hydrogen and other solar fuels. In this work, La0.8Ca0.2MeO3±d (Me ¼ Co, Ni, Fe and Cu) perovskites have been synthesised by a modified Pechini method and evaluated as materials for hydrogen production by two step thermochemical water splitting cycles. Performing the thermal reduction at temperatures of 1200 and 1000 C, while the oxidation is done at 800 C, allows a remarkable and stable hydrogen production after 5 consecutive cycles. However, the perovskites suffer changes in the structure after each redox cycle, with potential effects in the long-term cyclic operation. On the contrary, the isothermal thermochemical cycles at 800 C produce a stable amount of hydrogen with each consecutive cycle maintaining the perovskite structure. This hydrogen production ranges from 3.60 cm3 STP/gmaterial$cycle for the material with the lowest productivity (La0.8Ca0.2FeO3±d) to 5.02 cm3 STP/gmaterial$cycle for the one with the highest activity (La0.8Ca0.2NiO3±d). Particularly the Ni-based material shows the highest H2 productivity accompanied by very good material stability after 15 consecutive cycles, being possible to combine with current solar thermal facilities based on concentrated solar power technologies like plants with central receivers.