Feasibility of electrochemical regeneration of activated carbon used in drinking water treatment plant. Reactor configuration design at a pilot scale

This work evaluates the feasibility of electrochemical regeneration of granular activated carbon used in drinking water treatment plants as a real alternative to thermal regeneration. Two pilot-plant-scale reactors, with a capacity of 10−15 kg, have been designed using two different configurations, parallel plate electrodes and concentric cylindrical electrodes. The optimization of the anode material has also been studied and Pt/Ti, RuO2/Ti and IrO2/Ti have been used. After the regeneration and, thus, recovery of the porosity the samples were tested in the adsorption of bisphenol A. In the electrochemical regeneration, recovery of the porosity of spent activated carbon until 100 % and 96 % with respect to the pristine activated carbon using Pt/Ti anode after 3 h of treatment, has been achieved. The regeneration process produces a small increase in the number of surface oxygen groups. No important differences have been observed among the tested anodes and RuO2/Ti and IrO2/Ti can be an economic alternative to Pt/Ti. Bisphenol A adsorption kinetics was slower in regenerated activated carbons probably due to the formation of surface oxygen groups. However, the adsorption capacity was similar in the regenerated samples and the pristine one.This work was supported by the European Union-Horizon 2020 (PORTABLECRAC - SPIRE09 - 2017 Nº 768905)

Valorization of Posidonia oceanica biomass: Role on germination of cucumber and tomato seeds

Biostimulants are organic compounds from plant sources such as botanical extracts and bioactive substances that promote plant growth, enhance photosynthesis and increase crop quality. The accumulation of detached Posidonia oceanica leaves on coasts of the Mediterranean Sea results in economic problems, due to the rejection of the tourists who frequent the beaches in the summer months. However, it is a plant with high content of secondary metabolites that can be used in sustainable agriculture. In this study we investigated the physicochemical characterization of Posidonia oceanica extracts with three different solutions and their application in tomato and cucumber seeds germination. The results showed that the aqueous extract of Posidonia oceanica had a high concentration of macro and micronutrients, as well as secondary metabolites with bioactive activity. The aqueous extract had a beneficial effect on both leaf and root growth on tomato seeds, specifically, an increase of 76% for the relative root growth and 73% for the germination index was obtained with respect to the control using the sample with the intermediate dilution (POe0.5). In addition, the extracts did not show toxicity to either germination or growth of the tomato plant. As for cucumber seed germination, the improvement was less significant and did result in a phytotoxic effect on both germination and plant growth. The most diluted extract had better results on seed germination. Therefore, the application of aqueous extracts of Posidonia oceanica were suitable to be appropriate for tomato germination and in turn contribute to eliminate the lots of Posidonia oceanica remains recovered in summer months in Mediterranean beaches.This study was funded by Ministerio de Economía y Competitividad Spain (CGL2016-79054-R)

Enhancing Salt Stress Tolerance in Tomato (Solanum lycopersicum L.) through Silicon Application in Roots

Soil salinization poses a significant threat to agricultural productivity, necessitating innovative agronomic strategies to mitigate its impact. This study focuses on improving salt stress resistance in tomato plants through the application of silicon (Si) in roots. A greenhouse experiment was carried out under normal conditions (control, and 1 and 4 mM Si) and under salinity stress (salt control, and 1 and 4 mM Si). Various parameters were analyzed in leaves and roots. Under normal conditions, tomato plants grown in non-saline conditions exhibited some toxicity when exposed to Na2SiO3. As for the experiments under salt stress conditions, Si mitigated oxidative damage, preserving root cell membrane integrity. The concentration of malondialdehyde was reduced by 69.5%, that of proline was reduced by 56.4% and there was a 57.6% decrease in catalase activity for tomato plants treated with 1 mM Si under salt stress. Furthermore, Fe uptake and distribution, under salt conditions, increased from 91 to 123 mg kg−1, the same concentration as that obtained for the normal control. In all cases, the lower dose produced better results under normal conditions than the 4 mM dose. In summary, this research provides a potential application of Si in non-fertigated crop systems through a radicular pathway

Electrochemical regeneration of spent activated carbon from drinking water treatment plant at different scale reactors

The electrochemical regeneration of real spent activated carbons (AC) used in drinking water treatment plants was studied at different reactor scales. The electrochemical regeneration was carried out in a 6 g filter-press cell and a 3.5 kg batch reactor, allowing the scaling-up of the process between the two electrolytic reactors. The effect of the electrolyte, the divided/undivided compartment configuration and the current density were studied in the filter-press cell. The effect of compartment configuration and the influence of the regeneration time were studied in the scaled-up reactor. A current density of 0.025 A cm−2 was used and the electrodes were Pt/Ti as anode and Pt/Ti and stainless-steel as cathode. The ACs were characterized by N2 adsorption isotherms to analyse the recovery of porosity and TPD-MS to analyse the AC surface after the electrochemical treatment. In filter-press cell, a recovery of the surface area of 96% was achieved after 8 h of treatment, by introducing the AC in the cathodic compartment using 0.05 M H2SO4 solution as electrolyte. In the 3.5 kg electrochemical reactor, 95% of the pristine AC surface area was recovered. Thus, electrochemical methods can provide a green alternative to the regeneration of spent AC.This work was supported by the European Union-Horizon 2020 (PORTABLECRAC - SPIRE09 - 2017 Nº 768905)

Validación de la tecnología electroquímica para la regeneración de carbón activado a escala de banco

The validation study of the electrochemical regeneration process of activated carbons (AC) used in water treatment plants saturated under real conditions has been carried out. The study has been performed using a bench-scale electrochemical reactor and the recovery of the porous texture has been analysed. Saturated AC from different brands and manufacturing methods have been studied. The results showed that it is easier to recover the porosity of the AC prepared by agglomeration than those produced by direct activation process. In addition, it is shown that the larger the surface area of the spent AC, the better is the regeneration efficiency achieved. Specifically, to reach a good regeneration efficiency, the SBET of the spent sample should be higher than 600 m2/g. This is a similar value as that requested by the thermal regeneration companies for a successful regeneration of the AC.El estudio de validación del método electroquímico a escala de banco para la regeneración de carbones activados (CA) utilizados en condiciones reales en plantas de tratamiento de agua se ha realizado empleando CAs de distinta procedencia y forma de fabricación. Los resultados mostraron que los CAs preparados mediante aglomeración presentaron una mayor facilidad para la recuperación de la textura porosa que los fabricados mediante el proceso de activación directa. Además, se pone de manifiesto que, a mayor área superficial del CA usado, mayor es la eficiencia de la regeneración electroquímica. En concreto, se ha determinado que, para lograr una buena eficiencia de regeneración, el SBET del CA gastado debe ser superior a 600 m2/g. Este valor es el mismo que piden las empresas de regeneración térmica para que la regeneración del CA tenga éxito.This work was supported by the European Union-Horizon 2020 (PORTABLECRAC - SPIRE09 – 2017 No768905)

Characterization of Technosols for Urban Agriculture

Soil characterization is essential for planning activities in urban areas in order to detect potential risks and understand the possible impacts derived from those activities. Nine soils located in Alicante (southeast of Spain) developed over construction debris were studied. Soil characteristics including mineralogy, elemental composition and metal availability were analyzed in two consecutive years, 2019 and 2020. These soils were similar to forest soils in the same area, with no evidence of asbestos clays or excess harmful elements. However, the use of DTPA extraction revealed high levels of Mn and Zn in some soils. Organic carbon and metals extracted with DTPA differed in 2019 and 2020, but no relationship between metal-DTPA and organic carbon content was observed. In general, organic matter content was higher in 2019, and elements extracted with DTPA were lower. The above-average rainfall in 2019 could have led to the washing away of dissolved materials and fine soil particles, decreasing elemental availability on the one hand, while promoting the development of natural vegetation, increasing soil organic matter, and immobilizing elements in living organisms on the other hand. The fact that the metal mobility varies depending on weather and soil characteristics is important when planning. Despite the demonstrated advantages of increasing urban green areas from an environmental and social point of view, we should not forget the materials on which urban soils are developed. Therefore, it is essential to establish annual plans for monitoring variations in the availability of heavy metals. This is of the most relevance when the plants are for human consumption. It is therefore also necessary to control the vegetables that grow on these soils and, in the event of possible problems, use the soil for gardening

Effect of concentration and flow rate of electrolyte on electrochemical regeneration of activated carbon at pilot-plant scale

Few research has investigated the problem of regeneration of activated carbon once it has been saturated by organic and inorganic contaminants. Among the regeneration methods, electrochemical technology is one of the most advanced, demonstrating its effectiveness in pilot-plant scale experiments using samples obtained from drinking water treatment plants. In the present study, the optimization of a parallel plate electrochemical reactor with a capacity of 15 kg of activated carbon, has been achieved regarding the electrolyte concentration and flow rate. A regeneration efficiency of approximately 90% was achieved with a 0.25 M H2SO4 concentration, while lower concentrations resulted in a voltage exceeding the acceptable limits for this type of installation. In addition, higher flow rates imply a higher recovery of the porous texture of the regenerated activated carbon. This is, to the best of our knowledge, the first report where these two experimental variables are optimized in a pilot-scale process with real saturated activated carbon samples with different types of pollutants adsorbed in the activated carbon.This work was supported by the European Community‘s Framework Programme for Research and Innovation Horizon 2020 [grant number 768905]. The researchers would like to thank Empresa Mixta Valenciana de Aguas S.A. and Global Omnium Medioambiente S.L. (Valencia, Spain) for the supply of spent activated carbon samples

Effectiveness of Oxygen-Saturated Seawater Injections and Air Sparging Technologies in Remediation of Coastal Marine Sediments from Sludge

The occurrence of hypoxic muddy sediments on shallow beaches and other sheltered areas is a well-known environmental problem, which negatively affects coastal areas, tourism potential, the public use of beaches and sediment biodiversity. The usual solution is limited to dredging and removal of sludge to a landfill site. In this study, a laboratory-scale experiment was performed to determine the effectiveness of two technologies: a modification of air sparging and a new approach based on injecting oxygen-saturated seawater in hypoxic muddy sediments (oxygen-saturated seawater injections method), for remediating sludge in coastal sediments, minimizing environmental impact respect to dredging. Our results showed that both technologies significantly increased dissolved oxygen content in pore water, facilitating the oxidation of more than 90% of the organic matter, and other reduced inorganic compounds such as sulphide, with the consequent increase in sulphate concentration from 0.3 to 3.0 g·L−1. Moreover, a rise of redox potential from − 258 mV to above 200 mV, and a dramatic drop in chemical oxygen demand were also indicators that oxic conditions had been restored. After 65 days, soft, black, muddy and hypoxic sediment with high organic matter content and a characteristic foul odour was transformed into well-oxygenated sediment, which had a low organic matter content and had lost its initial shiny black colour and odour. The main difference between both technologies was the depth influenced by sediment remediation; oxygen-saturated seawater injections affected deeper areas than clean pressurized air injections.This work was supported by Own Research Program to MC and CB of the University of Alicante (Grant Number [PC15-05]) and Route Pont SL

Aprendizaje POGIL: implementación de herramientas para trabajo grupal síncrono

La estrategia de aprendizaje en la que se ha centrado este trabajo es el método POGIL (Process Oriented Guided Inquiry Learning), el cual está orientado a mejorar el trabajo del alumnado en grupo haciendo uso de diferentes roles participativos. Este método de carácter cooperativo se aplicó en diferentes asignaturas impartidas en la Facultad de Ciencias, tanto de grado como de postgrado, obteniendo resultados que reflejan la aceptación del método POGIL por parte del alumnado y una mejora en la adquisición de los conceptos en comparación con las clases tradicionales. En esta experiencia se ha planteado el desafío de implementar este método en clases en formato no presencial (online), ya que la situación sanitaria acaecida ha limitado la asistencia del alumnado. A partir de las encuestas realizadas por el alumnado y comparando con los resultados de las encuestas de años anteriores, se puede afirmar que este método se ha aplicado de manera satisfactoria tanto en clases presenciales como en clases online. Adicionalmente, se observó que el contraste entre clases POGIL online y las clases expositivas clásicas es aún mayor que en años anteriores cuando se aplicaba el método POGIL en clases presenciales

Strategies to promote University-Business communication and promote the employment of students throughout their educational career

Depto. de Ingeniería Química y de MaterialesFac. de Ciencias QuímicasFALSEsubmitte