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Se describe la construcción de una torre de intercambio iónico de lecho mixto, y se prueba en una instalación experimental, por la que se circula agua industrial que es utilizada para alimentar a diferentes calderas. Se detallan y analizan los datos experimentales obtenidos con aguas brutas procedentes de pozo y desaladora, así como del agua desmineralizada. Los resultados obtenidos faculta a indicar que frente a otros procedimientos, la desmineralización es más adecuada y resulta económicamente viable para tratar el agua de calderas., Depto. de Mineralogía y Petrología, Fac. de Ciencias Geológicas, TRUE, pub

Microplastics (MPs) and artificial fibers (AFs) have been detected suspended tens of meters above ground level in the atmosphere, yet empirical data on them remain scarce. This study aimed to investigate the presence of MPs and AFs in the digestive and respiratory systems of two abundant bird species, the Common House Martin (Delichon urbicum) and the Common Swift (Apus apus), within the Community of Madrid, Spain. Given that these birds spend the majority of their lives airborne, engaging in activities such as mating and sleeping during flight, the research sought to assess the potential of using these bird species as bioindicators for suspended atmospheric MPs and AFs. Samples were obtained from necropsies of birds (N = 24) collected primarily between spring and summer from 2021 to 2023. Only individuals that died within the initial 24-hour period and had not been fed were selected for examination to avoid contamination. MPs and AFS were identified by micro-FTIR, characterized and quantified. Results revealed that 75 % of the sampled birds exhibited at least one MPs in their respiratory and/or digestive system. All identified MPs were fibers, with polyester (PES) being the most predominant (48 %), followed by acrylic fibers (ACR; 28 %), and polyethylene (PE; 18 %). The average concentrations in the respiratory system were 1.12 ± 0.45 MPs/specimen and 2.78 ± 1.04 AFs/specimen for Common Swift and 0.75 ± 0.30 MPs/specimen and 0.75 ± 0.36 AFs/specimen for House Martin. In the digestive system, these were 1.92 ± 0.72 MPs/specimen and 3.42 ± 0.69 AFs/specimen for Common Swift, and 1.34 ± 0.50 MPs/specimen and 1.39 ± 0.47 AFs/specimen for House Martin. Birds collected areas with high population density located in the direction of the prevailing winds showed a concentration of MPs significantly higher in the digestive system. Taken together, these findings confirmed the potential use of these birds as bioindicators for monitoring of suspended atmospheric MPs and AFs., Ministerio de Ciencia, Innovación y Universidades (España), Plastics Europe, Enviroplanet, Sección Deptal. de Farmacología y Toxicología (Veterinaria), Fac. de Veterinaria, TRUE, pub

Piggery wastewater generation has become an environmental problem which must be solved by managing the residue through appropriate treatment. One promising technology is the use of photobioreactors where microalgae and bacteria act symbiotically to remove nutrients, which allows to reduce costs in wastewater treatment and in microalgae production by using the wastewater as culture media. In this treatment process, a valuable biomass is generated that can be used to produce several components and bioproducts. However, most of the algal components such as proteins and carbohydrates are found within a cell wall that should be disrupted to extract them by trying to cause low degradation of the solubilized components and considering the presence of pollutants. So, this thesis focusses on the valorization of the algal biomass grown on piggery wastewater by different technologies. Likewise, the economic and environmental viability of some proposed valorization processes was studied., La generación de aguas residuales de purines se ha convertido en un problema medioambiental que debe resolverse gestionando estos residuos mediante un tratamiento adecuado. Una tecnología prometedora es el uso de fotobiorreactores donde microalgas y bacterias actúan simbióticamente para eliminar los nutrientes, lo que permite reducir costes en el tratamiento de las aguas residuales y en la producción de biomasa algal al utilizar las aguas residuales como medio de cultivo. En este tratamiento se genera una biomasa valorizable que puede utilizarse para producir diversos componentes y bioproductos. Sin embargo, la mayoría de los componentes de las algas, como proteínas y carbohidratos, se encuentran dentro de una pared celular que debe romperse para poder extraerlos, con una baja degradación de los componentes solubilizados y teniendo en cuenta la presencia de contaminantes. Así, esta tesis se centra en la valorización de la biomasa algal cultivada en aguas residuales de purines mediante diferentes tecnologías. Así mismo, se ha estudiado la viabilidad económica y ambiental de algunos procesos de valorización propuestos., Escuela de Doctorado, Doctorado en Ingeniería Química y Ambiental

El presente Trabajo Fin de Grado consiste en un estudio de la influencia de las condiciones ambientales para la orientación de una nave industrial, con especial atención al viento y a la luz solar, que permitirá la generación de energía eléctrica a través de placas solares instaladas sobre su cubierta. Para ello, se diseñará un caso de referencia en el programa de diseño estructural Robot y se calculará el correcto dimensionamiento de las barras de la estructura, así como la producción fotovoltaica de los módulos solares gracias a la herramienta digital PVGIS. Por último, se estudiarán varias posibilidades en la orientación e inclinación de la cubierta, con el fin de analizar los resultados., This Final Degree Project consists of a study of the influence of environmental conditions on the orientation of an industrial unit, paying special attention to wind and sunlight, which would allow the electricity generation through solar panels installed on its roof. For this purpose, a reference case will be designed with the Robot structural software and the accurate sizing of the structural bars will be calculated, as well as the photovoltaic production of the solar modules thanks to the PVGIS digital tool. Finally, various possibilities in the orientation and the roof’s angle will be considered, in order to analyze the results., Departamento de Construcciones Arquitectónicas, Ingeniería del Terreno y Mecánica de los Medios Continuos y Teoría de Estructuras, Grado en Ingeniería Mecánica

Producción Científica, Dunaliella salina has been recognized as an excellent biomass source of carotenoid, which can be used as a natural orange coloring agent for food products. The most eco-friendly approach for extracting carotenoid is through supercritical carbon dioxide extraction, as it yields highly concentrated extracts while preventing pigment thermal degradation. However, there are limitations when a lipophilic extract is considered a food ingredient, in particular very difficult handling and low solubility in water-based products. The aim of this study was to develop a hydrosoluble form of a natural carotenoid-rich extract recovered from algae biomass within a biorefinery concept to be incorporated in aqueous-based food products. A two-step process was developed, starting with the emulsification of the supercritical extract into a mixture of maltodextrin and gum arabic, using soy lecithin as an emulsifier. The emulsification was followed by a spray-drying step. The impact of process variables on the encapsulation yield, efficiency, emulsion properties, and particle characteristics was studied. The resulting particles exhibited an intense orange color and good water dispersibility, facilitating uniform yellow coloring when incorporated into an aqueous-based product. Overall, spray-drying emulsions containing carotenoids derived from Dunaliella salina prove to be a promising strategy for the global market demand for natural colorants., Fundación Portuguesa para la Ciencia y la Tecnología (FCT) - (grant SFRH/BPD/79533/2011), IF Starting Grant - GRAPHYT (IF/00723/2014), Laboratorio Asociado de Química Verde LAQV y Fondo Europeo de Desarrollo Regional (FEDER) - (UID/QUI/50006/2013, POCI-01-0145-FEDER–007265), European Knowledge-Based Bioeconom (KBBE) P7 - (project 613870), Fundación Portuguesa para la Ciencia y la Tecnología (FCT) - (PEst- OE/EQB/LA0004/2011), Fundación Portuguesa para la Ciencia y la Tecnología (FCT)/Ministerio de Ciencia y Enseñanza Superior de Portugal y Fondo Europeo de Desarrollo Regional (FEDER) - iNOVA4Health (LISBOA-01-0145-FEDER-007344)

Producción Científica, This study assesses the early outcomes of the Poblenou Superblock in Barcelona and a nature-based solutions project in Valladolid. By critically analysing available data and collecting residents’ perceptions, the analysis depicts to what extent the project’s interventions enhanced environmental quality and residents’ well-being. Results highlight the role of the traffic space recovery strategy in Barcelona as a driver for larger benefits, allowing the creation of socially attractive public spaces along with greenery. This led to more appreciated interventions, possibly boosted by the post-pandemic context and city branding strategy. A potential downside concerns the likely gentrification processes triggered by these improvements.

Producción Científica, Recent European Green Deal includes decision to become carbon neutral and even carbon negative region in order to tackle the climate crisis. Main technical challenge and a key factor in techno-economic analysis of the energy system of the future, based on variable renewable energy sources, is their variable production and its ntegration. In order to deal with this problem in long-term energy planning, different approaches have been tried, focusing on overcapacity, storage capacities and sectors coupling with heating and transport. In this research, different flexibility options, storage and demand response technologies are modelled on a national energy systems level. With the case study area modelled in EnergyPLAN model, the goal of the research is to show how each flexibility option influences the economically feasible generation capacities of renewable energy sources, storage technologies and demand response in order to reach a certain share of renewable energy in final energy consumed. To follow the numerous possible configurations of the system, flexibility index for each option and a flexibility vector for each scenario are introduced. Results show which flexibility options play key role in important steps of energy transition to 70%, 80%, 90% and 100% RES energy system., Project LOCOMOTION, funded through European Union’s Horizon 2020 research and innovation programme, under grant agreement No 821105. Ministry of Education, Science and Technological Development of the Republic of Serbia, the Agreement on the implementation and financing of scientific research of the Institute of Technical Sciences of SANU in 2020 (Registration number: 451-03-68 / 2020-14 / 200175).

The anaerobic digestion process has been studied for years, leading to numerous applications. Research in this technology has been focused on improvement through various scientific approaches: the most fundamental study of the process, the kinetics of the stages, the final use of the products and by-products obtained as well as pretreatments for process optimization, among other aspects. This biological process presents a significant opportunity for renewable energy generation and its integration into the energy mix. Furthermore, its implementation could lead to savings in greenhouse gas emissions and the mitigation of fossil fuel use associated with population growth. Emissions captured through controlled anaerobic digestion have enormous potential when dealing with agricultural organic substrates or residues from the anthropogenic activity since, these emissions account for 40% of methane released into the atmosphere spontaneously. Therefore, it is imperative to focus efforts on mitigating this effect through a better management of this agricultural activity within the primary sector. This involves a double approach to transform the sector by enhancing its profitability through the management of generated by-products and by mitigating its impact as a source of greenhouse gases, ultimately making it a much more sustainable process. In this context, livestock waste, by-products from basic cereal crops, or the agricultural product industry can significantly contribute to bioenergy generation in the primary sector. However, the biological transformation within the anaerobic digestion process will vary for each type of substrate due to their distinct chemical composition and physical properties. Thoroughly studying the different available by-products for management through anaerobic fermentation is critical to maximise their transformation. In this way, technological development in the anaerobic digestion process applied to the agricultural sector is fundamental for a, El proceso de digestión anaerobia se ha estudiado desde hace años resultando en una gran cantidad de aplicaciones. Las investigaciones dentro de esta tecnología se han orientado hacia la mejora con diferentes enfoques científicos: el estudio más fundamental del proceso, la cinética de las etapas, el uso final de los productos y subproductos obtenidos, o los pretratamientos para la optimización del proceso, entre otros. Este proceso biológico puede suponer una gran oportunidad para la generación de energía renovable y su integración dentro del mix energético, además de que su implementación conllevaría un ahorro en emisiones de gases de efecto invernadero y la mitigación del uso de combustibles fósiles derivado del crecimiento de la población. Las emisiones captadas por la digestión anaerobia controlada tienen un potencial enorme cuando se trabaja con sustratos o residuos orgánicos agrícolas (de origen antropogénico) ya que, de manera espontánea, suponen actualmente el 40 % de las emisiones de metano a la atmósfera. Es, por tanto, imprescindible centrar parte de los esfuerzos en mitigar este efecto con una mejor gestión de esta actividad agrícola dentro del sector primario con un doble enfoque para convertir al sector mejorando su rentabilidad, por la gestión de los subproductos generados, así como atenuando su efecto como fuente de gases de efecto invernadero y, en suma, transformarlo en un proceso mucho más sostenible. En este contexto, los desechos ganaderos, subproductos de las plantaciones de cereales básicos o de la industria de productos agrícolas, pueden contribuir notablemente a la generación de bioenergía en el sector primario. No obstante, la transformación biológica dentro del proceso de digestión anaerobia va a ser diferente para cada tipo de sustrato por su diferente composición química y propiedades físicas y es imprescindible estudiar a fondo los diferentes subproductos disponibles para su gestión a partir de la fermentación anaeróbica con el objeto d, Escuela de Doctorado, Doctorado en Ingeniería Química y Ambiental

Producción Científica, The world is facing a global sustainability crisis affecting environmental systems and society. Addressing these issues requires a multi-dimensional approach that can integrate energy, water, and environment Systems, as well as provide scientific policy advice. In this study, an updated version of an Integrated Assessment Model (IAM) was used, together with new data compatible with Shared Socioeconomic Pathways (SSPs) projections, to significantly improve the work developed before. SSP climate data (temperature, precipitation, and total radiative forcing) and socioeconomic data (population and GDP) were loaded into the IAM, together with different scenario parameters. By analyzing varying socioeconomic scenarios, mitigation efforts, and adaptation strategies, this study assesses their impact on primary energy demand and, consequently, their impact on hydropower potential production. Our results show diverse energy paths, strongly dependent on the future scenario. Energy demand could increase up to 160%; however, several projections foresee a decline in hydropower production to minus 46% due to both climate change and socioeconomic transformation. Our findings highlight the importance of considering a range of potential future scenarios in energy planning and policy development. The varied outcomes across the considered scenarios emphasize the need for flexibility in strategies to accommodate for uncertainties and address the challenges posed by divergent trajectories in hydropower use and renewable energy shares., Fundación Portuguesa para la Ciencia y la Tecnología (FCT) - (project UIDB/00329/2020), Unión Europea, European Union’s Horizon 2020 - (grant 821105)

En este trabajo se desarrolla la ingeniería básica de una planta de producción de 250.000 t/año de queroseno sintético (SAF) mediante hidrógeno verde, CO2 capturado y la reacción de FischerTropsch a bajas temperaturas. El proceso presenta una conversión total del CO2 en queroseno y diésel, generándose como único subproducto agua (el rendimiento de hidrógeno a agua es de un 30%) El precio mínimo de venta calculado para el queroseno sintético es de 1932 €/tonelada, recuperándose la inversión inicial en 9 años. Finalmente, desde un punto de vista medioambiental, la intensidad energética es de 19 MJ/kg producto, con un consumo de agua de 0,02 m3 agua/kg producto y unas emisiones de 0,3 kg CO2 equivalente/kg producto, This work develops the basic engineering of a plant for the production of 250,000 t/year of synthetic kerosene (SAF) using green hydrogen, captured CO2 and the Fischer-Tropsch reaction at low temperatures. The process features full conversion of CO2 into kerose and diesel, generating water as the only by-product (the hydrogen to water yield is 30%). The minimum selling price calculated for synthetic kerosene is 1932 €/tonelada, recovering the initial investment in 9 years. Finally, from an environmental point of view, the energy intensity is 19 MJ/kg product, with a water consumption of 0.02 m3 water/kg product and emissions of 0.3 kg CO2 equivalent/kg product, Departamento de Ingeniería Química y Tecnología del Medio Ambiente, Grado en Ingeniería Química

Producción Científica, Current ozone (O3) concentration levels entail significant damages in crop yields around the world. The reaction of the emitted precursors (mostly methane and nitrogen oxides) with solar radiation contribute to O3 levels that exceed established thresholds for crop damage. This paper shows current and projected (up to 2080) relativeyield losses (RYLs) driven by O3 exposure for different crops and the associated economic damages applying dynamic crop production and prices that are calculated per region and period. We adjust future crop yields in the Global Change Assessment Model (GCAM) to reflect the RYLs and analyze the effects on agricultural markets. We find that the changes (generally reductions) in O3 precursor emissions in a reference scenario would reduce the agricultural damages, compared to present, for most of the regions, with a few exceptions including India, where higher future O3 concentrations have large negative impacts on crop yields. The annual economic impact of O3 driven losses from 2010 to 2080 are, in billion US dollars at 2015 prices ($B), 5.0–6.0, 9.8–18.8, 6.7–10.6 and 10.4–12.5 for corn, soybeans, rice and wheat, respectively, with the large losses for wheat and soybeans driven by their comparatively high responses to O3. When O3 effects are explicitly modelled as exogenous yield shocks in future periods, there is a direct impact in future agricultural markets. Therefore, the aggregated net present value (NPV) of crop production would be reduced around by $90.8 B at a global level. However, these changes are not distributed evenly across regions, and the net present market value of the crops would increase by up to $118.2 B (India) or decrease by up to $59.2 B (China)., Basque Government through the BERC 2018–2021 and the Spanish Government through María de Maeztu excellence accreditation MDM-2017-0714. US Environmental Protection Agency, under Interagency Agreement DW08992459801. Ministry of Economy, Industry and Competitiveness of Spain (RTI2018-099858-A- 100 and RTI2018-093352-B-I00). support from the Basque Government (PRE_2017_2_0139). The European Union’s Horizon 2020 research and innovation program under grant agreement no. 821105 (LOCOMOTION project). Financed by the programme Ramon y Cajal from the Spanish Ministry of Economy, Industry and Competitiveness (RYC-2017-22143).

Cada vez se busca más reducir emisiones y fomentar prácticas de consumo más sostenibles. Para ello, se ha desarrollado un método en el que el CO2 capturado en disoluciones acuosas de aminas se reduzca con hidrógeno a alta presión en un reactor discontinuo Parr operando en batch para obtener ácido fórmico, utilizando como catalizador Pd/C al 5%. Se probarán diferentes aminas con el fin de encontrar aquella que proporcioné el mejor rendimiento de eliminación de CO2 a diferentes condiciones (75ºC y 120 ºC a 75 bar), estimándose que una de las mejores en la captura del CO2 es la di-isopropilamina (DIPA), ya que proporciona muy buenos rendimientos de formación de ácido fórmico de más del 80% a 120 ºC. Además, se ha estudiado la recuperación de aminas después de reacción a 120 ºC a través del análisis de H-NMR, obteniendo generalmente rendimientos de recuperación muy altos, superiores al 50%., There is an increasing focus on reducing emissions and encouraging more sustainable consumption practices. To this end, a method has been developed in which CO2 captured in aqueous amine solutions is reduced with hydrogen at high pressure in a batch Parr batch reactor to obtain formic acid, using 5% Pd/C as catalyst. Different amines will be tested to find the one that provides the best CO2 removal performance at different conditions (75ºC and 120 ºC at 75 bar), estimating that one of the best in CO2 capture is di-isopropylamine (DIPA), as it provides very good formic acid formation yields of more than 80% at 120 ºC. In addition, the recovery of amines after reaction at 120 ºC has been studied through H-NMR analysis, generally obtaining very high recovery yields of over 50%., Departamento de Ingeniería Química y Tecnología del Medio Ambiente, Grado en Ingeniería Química

Producción Científica, Cereal straw stands out as one of the most abundant and globally distributed agricultural residues. Traditional applications cope with a limited amount of production, leaving the remainder in the field for natural decomposition. Managing cereal straw through controlled biological transformation under anaerobic conditions holds the potential to generate added value in the form of bioenergy. However, the lignocellulosic composition of these substrates poses challenges for organic degradation, often requiring energy-intensive pretreatments. A detailed study with a comprehensive calculation of the overall energy balance of the integrated process is proposed, aiming to provide real added value and replicability. Three scenarios for wheat straw transformation were investigated, incorporating two preliminary pre-treatment stages—mechanical milling and physicochemical steam explosion. Three conditions of pretreatment were essayed, varying the time exposure of the steam explosion. The subsequent energy integration analysis revealed that the process was optimized by up to 15% in the final energy balance when the steam explosion was set to 10 min. The macromolecular composition determination revealed that the thermal pretreatment reduced the lag phase of the hydrolysis step through hemicellulose breakdown., Junta de Castilla y León y Unión Euopea (UE)-Fondo Europeo de Desarrollo Regional (FEDER) - (grant CL-EI-2021-07), Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación (AEI) - (grant PID 2020-114918RB-I00), Union Europea, Programa LIFE, LIFE SMART AgroMobility - (grant LIFE19 CCM/ES/001206)

Flexographic printing technology is an economical, productive, low maintenance and versatile technology. However, the removal of these inks by the traditional flotation process during paper recycling is not possible since they remain dissolved in the waters, making necessary the development of alternative methods. Recent studies have revealed the potential use of nanocellulose (NC) combined with a cationic polyacrylamide to remove flexographic inks from wastewater. The use of a natural polymer, such as chitosan, would be an important improvement of this treatment because NC and chitosan are the two most abundant natural polymers with interesting properties, such as non-toxicity and biodegradability. Therefore, in this study the decolorization of three flexographic inks (copper phthalocyanine blue, carbon black and diarylide yellow) by the sequential addition of cellulose nanofibers, produced from recycled paper, and chitosan has been evaluated. Results show that this eco-friendly approach has high potential for the removal of water-based inks with an almost 100% reduction of turbidity and ink from the wastewater. Moreover, the final sludge containing nanocellulose and inks could be used to reinforce the pulp of the middle layers of carton board, improving the mechanical properties of the product and reducing waste generation., Comunidad de Madrid (Spain), MINECO, Depto. de Ingeniería Química y de Materiales, Fac. de Ciencias Químicas, TRUE, pub

Roads have pervasive impacts on wildlife, including habitat loss and fragmentation, road mortality, habitat pollution and increased human use of habitats surrounding them. However, the effects of roads on interspecific interactions are less understood. Here we provide a synthesis of the existing literature on how species interactions may be disrupted by roads, identify knowledge gaps, and suggest avenues for future research and conservation management. We conducted a systematic search using the Web of Science database for each species interaction (predation, competition, mutualism, parasitism, commensalism and amensalism). These searches yielded 2144 articles, of which 195 were relevant to our topic. Most of these studies focused on predation (50%) or competition (24%), and less frequently on mutualism (17%) or, parasitism (9%). We found no studies on commensalism or amensalism. Studies were biased towards mammals from high‐income countries, with most conducted in the USA (34%) or Canada (18%). Our literature review identified several patterns. First, roads disrupt predator–prey relationships, usually with negative impacts on prey populations. Second, new disturbed habitats created in road corridors often benefit more competitive species, such as invasive species, although some native or endangered species can also thrive there. Third, roads degrade mutualistic interactions like seed dispersal and pollination. Fourth, roads can increase parasitism rates, although the intensity of the alteration is species specific. To reduce the negative impacts of roads on interspecific interactions, we suggest the following management actions: ( i ) verges should be as wide and heterogenous as possible, as this increases microhabitat diversity, thus enhancing ecosystem services like pollination and seed dispersal; ( ii ) combining different mowing regimes can increase the complexity of the habitat corridor, enabling it to act as a habitat for more species; ( iii ) the use of de‐ic, Comunidad de Madrid (2018T1/AMB10374 y 2022-5A/AMB-24242), Complutense University of Madrid (CT63/19-CT64/19), Depto. de Biodiversidad, Ecología y Evolución, Fac. de Ciencias Biológicas, TRUE, pub

This work has been supported under contract EUI2008-03600 and CTQ2010-11765-E., Bioconversion of biodiesel-derived waste glycerol into high-value products is proposed as a solution to improve economic viability of biorefineries. Several microorganisms are able to metabolize glycerol into 2,3-butanediol (2,3-BD), a promising bulk chemical with wide applications: solvent, fuel additive, and feedstock for synthetic rubber production, among them. In the present work, a wide screening of microorganisms present both into the waste water treatment system in a biodiesel industry and in culture collections was carried out in order to evaluate their potential as new 2,3-BD producer biocatalysts. Two microorganisms for 2,3-BD production from glycerol as sole carbon source have been selected, namely Raoultella planticola CECT 843 and Raoultella terrigena CECT 4519. Raoultella strains belong to the non‐pathogenic bacteria class (biosafety level 1). This genus has not been previously described as biocatalyst for the studied process. The influence of operational temperature, organic acid addition, and yeast extract concentration on 2,3-BD yield and productivity have been studied through Taguchi design methodology as well as initial glycerol concentration. Based on these results, the feasibility of the process employing pure glycerol and different samples of raw glycerol has been demonstrated., Depto. de Ingeniería Química y de Materiales, Fac. de Ciencias Químicas, TRUE, pub

Producción Científica, In recent years, by expanding cities, air pollution has become one of the most important problems caused by humans. Tehran, as the capital of Iran, is expanding gradually and its population is rising day by day. Therefore, the increase in human activities causes many problems, such as air pollution, in this area. In this study, data from Sentinel-5 for Tehran city are used from the last month of 2018 to present and collected from the Google Earth Engine. Three main parameters of air pollution are studied, including aerosol, ozone and CO. Different statistics of each parameter are calculated. Then, temporal evolutions are analyzed using Statgraphics. From the analysis, the calculated aerosol median is −0.555 mol m−2 and the interquartile range is 1.248 mol m−2. For the ozone parameter, the median is calculated to be 0.131 mol m−2 and the interquartile range is 0.015 mol m−2. Also, for the CO parameter, the median is 0.037 mol m−2 and the interquartile range is 0.011 mol m−2. The total trend of aerosol is increasing, especially during the summer months, when aerosol amounts are higher than in the winter months. Our statistics show a decreasing trend for the ozone parameter, but in the winter months, ozone is higher than in the summer months. The trends for aerosol and ozone are statistically significant at the 95% confidence level. The trend of CO is totally stable but a little higher at the end of fall and during the first days of winter.

Ammonia can have significant impacts on air quality, water, ecosystems, and human health, emphasizing the importance of properly managing emissions of this compound. Ammonia is also present in wastewater from various human activities. These wastewater streams cause environmental and public health risks if not managed properly. Livestock wastewater, primarily composed of pig slurry, cow, and poultry manure, contains high concentrations of organic matter and nutrients. The most efficient biological process for the proper management of livestock wastewater is anaerobic digestion (AD) due to its ability to biotransform organic matter into biogas, although its capacity to remove nutrients is very limited. The biogas produced from AD of livestock wastewater is crucial for the environmental sustainability and the economic viability of animal farms, as well as for helping to mitigate climate change. AD is a natural process in which microorganisms decompose organic matter in the absence of oxygen, producing methane and carbon dioxide, along with a nutrient-rich effluent called digestate. However, high concentrations of certain compounds such as NH₃, which is found in nitrogen-rich organic wastes like manures, can inhibit the AD process. Elevated concentrations of total ammonia nitrogen can exacerbate inhibition, with levels above 400 mg NH₃-N L¯¹ causing significant issues. Strategies to mitigate NH₃ inhibition include the extraction of total ammonia nitrogen from digesters, aiming to improve biogas productivity and overall process stability. In recent decades, the removal of NH₃ from drinking water and wastewater has become a focal point in the water sector. Various technologies have been employed for NH₃ removal during the treatment of municipal, agricultural, livestock, and industrial wastewater, including physical, chemical, and microbial processes. Each method has its advantages and disadvantages, depending on specific treatment conditions., El amoniaco puede tener impactos significativos en la calidad del aire, el agua y los ecosistemas, así como en la salud humana, lo que resalta la importancia de gestionar adecuadamente las emisiones de este compuesto. El amoniaco también está presente en las aguas residuales provenientes de diversas actividades humanas. Estas aguas residuales conllevan riesgos ambientales y de salud pública si no se gestionan adecuadamente. Las aguas residuales ganaderas, constituidas principalmente por purines de cerdo, vaca y gallinaza, contienen altas concentraciones de materia orgánica y nutrientes. El proceso biológico más eficiente para la gestión adecuada de las aguas residuales ganaderas es la digestión anaerobia (DA) por su capacidad de biotransformar materia orgánica en biogás, aunque su capacidad para eliminar nutrientes es muy limitada. El biogás producido de la DA de aguas ganaderas es crucial para la sostenibilidad ambiental y la viabilidad económica de las granjas de animales, y para ayudar a mitigar el cambio climático. La DA es un proceso natural en el que los microorganismos descomponen la materia orgánica en ausencia de oxígeno, produciendo metano y dióxido de carbono, junto con un efluente rico en nutrientes llamado digestato. Sin embargo, las altas concentraciones de ciertos compuestos como el NH₃, que se encuentra presente en residuos orgánicos ricos en nitrógeno como los purines, pueden inhibir el proceso de DA. Concentraciones elevadas de nitrógeno amoniacal total pueden exacerbar la inhibición, con niveles por encima de 400 mg NH₃-N L¯¹ causando problemas significativos. Las estrategias para mitigar la inhibición de NH₃ incluyen la extracción de nitrógeno amoniacal total de los digestores, con el objetivo de mejorar la productividad del biogás y la estabilidad general del proceso. Las estrategias para mitigar la inhibición de NH₃ incluyen la extracción de nitrógeno amoniacal total de los digestores, con el objetivo de mejorar la produ, Escuela de Doctorado, Doctorado en Ingeniería Química y Ambiental

Producción Científica, The use of active coatings in fresh food packaging is an innovative technique that optimizes the functional properties of films, resulting in a longer product shelf life and reduced food waste. But, which is more sustainable, active packaging (AP) or conventional packaging (CP) for the packaging of fresh-cut products? To answer this research question, this study analyzes the environmental performance of AP during its life cycle for packaging a minimally processed fresh salad mix compared with CP, in terms of its manufacture and use. The AP is a bag that includes a bioactive component, oregano essential oil (OEO), which is an inhibitor of microbial growth, incorporated into an ethylene vinyl alcohol copolymer (EVOH) coating on a conventional polypropylene (PP) film. To this end, a Life Cycle Assessment (LCA) was carried out based on ISO 14040 and 14044, using the ReCiPe methodology. The results showed that using active packaging has a beneficial affect, reducing the amount of produced food by 30% compared with conventional packaging over the same period. The reductions in the studied impact categories were greater than 50% in most of them, with a 62% reduction in global warming. The proposed sensitivity analysis showed the difference between the disposal or treatment of waste generated by the packaging production process and the packaged product, indicating that this step is of great importance for the environmental impacts and sustainability of this process. In 80% of the scenarios analyzed, the AP achieved better results than the CP in terms of damage categories., Unión Europea (HORIZON-CL6- 2022-FARM2FORK-01) - (project 101084398T)

Producción Científica, Biogas is drawing attention as it can be a solution both to increase the renewable energy for heat or power supply and to help achieve a decarbonized economy. In this work, the measurements of the speed of sound of three mixtures of biogas from the biomethanation plant of the municipal waste of Valdemingómez, Madrid (Spain), are presented. The measurements were performed using an acoustic resonator, which is able to measure the speed of sound of gas mixtures with a relative expanded uncertainty of approximately 0.08%. A virial-type equation was also applied to fit the experimental values of the speed of sound, and the heat capacities as perfect gas were derived with uncertainties below 0.8%. In addition, the experimental results were compared with those calculated with the reference equations of state for natural gas mixtures such as GERG-2008 and AGA8-DC92. For both equations, the average relative deviations were less than 0.02% and 0.2% for the speed of sound and the heat capacities, respectively. These values are less than the uncertainties of these equations, demonstrating their reliability in predicting the thermodynamic behavior of biogas., Junta de Castilla y León y Unión Euopea (UE)-Fondo Europeo de Desarrollo Regional (FEDER) - (grants VA280P18 and CLU-2019-04)

Producción Científica, The carboxylate platform is a sustainable and cost-effective way to valorize wastes into biochemicals that replace those of fossil origin. Short-chain fatty acids (SCFAs) are intermediates generated during anaerobic fermentation (AF) and are considered high-value-added biochemicals among carboxylates. This investigation aimed to produce SCFAs through the AF of sugar beet molasses at 25 °C and semi-continuous feeding mode in completely stirred tank reactors. A particular focus was devoted to the role of hydraulic retention time (HRT) variation in SCFAs production and distribution profile. The highest SCFAs concentration (44.1 ± 2.3 gCOD/L) was reached at the HRT of 30 days. Caproic acid accounted for 32.5–35.5% (COD-concentration basis) at the long HRTs of 20 and 30 days due to the carbon chain elongation of shorter carboxylic acids. The findings of this study proved that HRT could be used to steer the anaerobic process toward the targeted SCFAs for specific uses. Furthermore, the successful operation at low-temperature conditions (i.e., 25 °C) makes the process economically promising., Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación (AEI)/10.13039/501100011033 - (grant CEX2019-000931-M)

Producción Científica, The valorization of fruit and vegetable residues (such as carrot discard) and their microbial conversion into 2,3-butanediol (BDO) can be considered as a very interesting way to reduce food waste and sustainably originate high value-added products. This work analyzes the valorization of carrot discard as feedstock for 2,3-butanediol (BDO) production by Paenibacillus polymyxa DSM 365. The influences of stirring and the presence of tryptone (nitrogen source) are studied. Furthermore, in order to evaluate the influence of the pre-culture medium (nitrogen source, nutrients, and pH) and the substrate, fermentation assays in simple and mixture semi-defined media (glucose, fructose, and/or galactose) were also carried out. As a result, 18.8 g/L BDO, with a BDO yield of 0.43 g/g (86% of its theoretical value), could be obtained from carrot discard enzymatic hydrolysate at 100 rpm, no tryptone, and pre-culture Häßler medium. No hydrothermal pre-treatment was necessary for BDO production from carrot discard, which increases the profitability of the process. Therefore, 18.8 g BDO, as well as 2.5 g ethanol and 2.1 g acetoin by-products, could be obtained from 100 g of carrot discard (dry matter)., Ministerio de Ciencia e Innovación/Agencia Estatal de Investigación (AEI)/10.13039/501100011033 - (project PID2020- 115110RB-I00, Junta de Castilla y León - (grant CLU 2017-09, CL-EI-2021-07, UIC 320)

Producción Científica, The use of mobile laser scanning to survey forest ecosystems is a promising, scalable technology to describe the 3D structure of forests at a high resolution. We use a structurally complex, mixed-species Mediterranean forest to test the performance of a mobile Handheld Laser Scanning (HLS) system to estimate tree attributes within a forest patch in central Spain. We describe the different stages of the HLS approach: field position, ground data collection, scanning path design, point cloud processing, alignment between detected trees and measured reference trees, and finally, the assessment of main tree structural attributes diameter at breast height (DBH) and tree height considering species and tree size as control factors. We surveyed 418 reference trees to account for omission and commission error rates over a 1 ha plot divided into 16 sections and scanned using two different scanning paths. The HLS-based approach reached a high of 88 and 92% tree detection rate for the best combination of scanning path and point cloud processing modes for the HLS system. The root mean squared errors for DBH estimates varied between species: errors for Pinus pinaster were below 2 cm for Scan 02. Quercus pyrenaica, and Alnus glutinosa showed higher error rates. We observed good agreement between ALS and HLS estimates for tree height, highlighting differences to field measurements. Despite the complexity of the mixed forest area surveyed, our results show that HLS is highly efficient at detecting tree locations, estimating DBH, and supporting tree height measurements as confirmed with airborne laser data used for validation. This study is one of the first HLS-based studies conducted in the Mediterranean mixed forest region, where variability in tree allometries and spacing and the presence of natural regeneration pose challenges for the HLS approach. HLS is a feasible, time-efficient, scalable technology for tree mapping in mixed forests with potential to support forest monitoring p, European Union’s Horizon 2020 and Innovation Program Marie Skłodowska-Curie - (Grant 956355), Junta de Castilla y León y Fondo Europeo de Desarrollo Regional (FEDER) - (projects “CLU‑2019‑01 and CL‑EI‑2021‑05—iuFOR Institute Unit of Excellence”), Fondo Europeo de Desarrollo Regional (FEDER), project Interreg COMFOR‑SUDOE - (grant SOE4/P1/E1012)

Producción Científica, In recent years, a number of microbial enzymes capable of degrading plastics have been identified. Biocatalytic depolymerization mediated by enzymes has emerged as a potentially more efficient and environmentally friendly alternative to the currently employed methods for plastic treatment and recycling. However, the functional and systematic study of depolymerase enzymes with respect to the degradation of a series of plastic polymers in a single work has not been widely addressed at present. In this study, the ability of a set of enzymes (esterase, arylesterase and cutinase) to degrade commercial biodegradable polymers (PBS, PBAT, PHB, PHBH, PHBV, PCL, PLA and PLA/PCL) and the effect of pre-treatment methods on their degradation rate was assessed. The degradation products were identified and quantified by HPLC and LC-HRMS analysis. Out of the three enzymes, Fusarium solani cutinase (FsCut) showed the highest activity on grinded PBAT, PBS and PCL after 7 days of incubation. FsCut was engineered and heterologous expressed in Escherichia coli, which conferred the bacterium the capability of degrading solid discs of PBAT and to grow in PBS as the sole carbon source of the medium., Société des Produits Nestlé S.A, Junta de Castilla y León y Fondo Europeo de Desarrollo Regional (FEDER) - (grant CL-EI-2021-07 and UIC 315)

Producción Científica, Ammonia (NH3) emissions from animal wastes are directly related to serious environmental problems and can be reduced by using gas-permeable membranes (GPMs) in animal housings, but not many studies have been conducted on the environmental impact of the entire system. Thus, the aim of this work was to analyze the environmental impacts caused by the implementation of GPM technology in a 920-animal swine farm with a closed cycle (i.e., birth, breeding, transition, and fattening take place on the same site), using life-cycle analysis (LCA). Two scenarios were studied: a reference scenario in which there was no NH3 reduction from the air captured in the sheds and a treatment scenario that used the GPM technology. The LCA results were evaluated by using the ReCiPe 2016 Midpoint (H) V1.04 method, showing that using the GPM technology had beneficial environmental impacts. Terrestrial acidification (TA) showed a reduction of 14.68 kg SO2 eq compared with the reference scenario, whilst human carcinogenic toxicity (HCT), human non-carcinogenic toxicity (HnCT), and land use (LU) showed reductions of 1.52 kg 1,4-DCB, 66.26 kg 1,4-DCB, and 44.55 m2a crop eq, respectively., Unión Europea - (project LIFE15-ENV/ES/000284)

Producción Científica, Fungi are a diverse and fascinating group of organisms that play an important role in various ecosystems, e.g., in the decomposition of organic matter and nutrient cycling. However, climate change poses a significant threat to these ecosystems and the organisms that inhabit them. Fluctuations in temperature and humidity can cause shifts in the distribution of fungi and negatively impact the ecosystems they inhabit. Yet fungi have the potential to play a role in mitigating the effects of climate change. With the use of biotechnology, fungi can help meet the United Nations Sustainable Development Goals, and their properties make them useful organisms in addressing the urgent challenges that humanity faces. For example, industrial biotechnology using fungi can lead to the production of goods that are more biodegradable, use less energy and produce less waste. Fungi have long been used in the production of enzymes, alkaloids, detergents, acids, and biosurfactants on an industrial scale. Recent research in the field of white biotechnology has made significant progress, and further advances are expected in the near future, especially in agricultural and environmental biotechnology. With this in mind, it is crucial to explore the use of fungi in novel and environmentally conscious technologies, as well as in mitigating the effects of climate change., Ministerio de Agricultura, Pesca y Alimentación - (project V4-1818), Junta de Castilla y León y Fondo Europeo de Desarrollo Regional (FEDER) - (projects CLU 2017-09, CL-EI-2021-07, UIC315, and VA266P20).), Agencia Eslovena de Investigación (ARRS) - (grants P4-0015 and P4-0430)

Producción Científica, In this work, a method to predict the output power of Photovoltaic (PV) cells using their Electroluminescence (EL) images is presented. The data used includes Electroluminescence Images and the value of the Max Power Point computed from the Current–Voltage Curve of the cells. The method is used as follows: Firstly, the images are preprocessed to improve their quality. After that, a comparison between different Machine Learning methods from Traditional ones, such as Random Forest or Gradient Boosting, to Deep Learning methods, such as Recurrent Neural Networks or Convolutional Neural Networks is performed. Another significant contribution of this paper is that it analyzes the problem of unbalanced data, trying to solve it using Synthetic Images created by a Generative Adversarial Network. Our results show that the best model is the Gradient-Boosting based method using a pre-trained Resnet50 as a feature extraction method with a Mean Absolute Error (MAE) of 0.0341 and a Mean Squared Error (MSE) of 0.00211. The results also shows how the models trained with the unbalanced dataset are capable of obtaining results similar to the models trained with the balanced dataset., Ministerio de Ciencia e Innovación de España (PID2020-113533RB-C33)

Producción Científica, In this study, we describe the characterization of three efficient chicken feather-degrading Streptomyces bacteria isolated from honeybee samples and assess the impact of their co-cultivation on this activity and antistaphylococcal activity. Streptomyces griseoaurantiacus AD2 was the strain showing the highest keratinolytic activity (4000 U × mL−1), followed by Streptomyces albidoflavus AN1 and Streptomyces drozdowiczii AD1, which both generated approximately 3000 U × mL−1. Moreover, a consortium constituted of these three strains was able to use chicken feathers as its sole nutrient source and growth in such conditions led to a significant increase in antibiotic production. S. griseoaurantiacus AD2 was the only strain that exhibited weak antimicrobial activity against Staphylococcus aureus. UPLC analyses revealed that a significant number of peaks detected in the extracts of co-cultures of the three strains were missing in the extracts of individual cultures. In addition, the production of specialized metabolites, such as undecylprodigiosin and manumycin A, was clearly enhanced in co-culture conditions, in agreement with the results of the antimicrobial bioassays against S. aureus. Our results revealed the benefits of co-cultivation of these bacterial species in terms of metabolic wealth and antibiotic production. Our work could thus contribute to the development of novel microbial-based strategies to valorize keratin waste., Fondo Europeo de Desarrollo Regional (FEDER), (grant TCUE 2021–2023) - (project 067/229111), Unión Europea, H2020-MSCA-IF-2016 - (grant UE-18-VANRESTREP-740080)

Producción Científica, Synthetic co-cultures can enhance pollutant bioconversion performance through synergistic effects among co-existing species. In this study, the potential of Methylocystis hirsuta and Methylocystis parvus to support poly(3-hydroxybutyrate) (PHB) production in co-cultivation with Rhodococcus opacus and Pseudomonas putida under a CH4:O2 atmosphere was assessed batchwise. The metabolic activation of almost all co-cultures studied was faster than that of single strain cultures, bringing higher methane and oxygen consumption rates. Higher PHB yields were achieved when coupling M. hirsuta with R. opacus (63 % w w−1) or with R. opacus and P. putida (64.4 % w w−1) compared to M. hirsuta alone (38.5 % w w−1). Interestingly, the combination of both R. opacus and P. putida with M. parvus reduced PHB accumulation to 42.2 % w w−1 compared to the content observed in M. parvus monocultures (62.2 % w w−1) and M parvus + R. opacus co-cultures (66.6 % w w−1)., Junta de Castilla y León - EU-FEDER [CL-EI-2021-07 y UIC 315], Ministry of Economic Development through the “Fondo per la Crescita Sostenibile – Sportello “Agrifood” PON I&C 2014-2020” (Prog. n. F/200125/01-03/X45)

Producción Científica, Nutrient recovery from the agri-food sector waste is an increasingly recognized option within the framework of the bioeconomy. Membrane technologies and chemical precipitation are among the best valued options for their economic and practical feasibility. In this study, the combination of gas-permeable membrane (GPM) technology for the recovery of nitrogen (N) and the chemical precipitation for phosphorous (P) recovery from anaerobically digested swine manure is evaluated. This work studies the effect of the membrane area and the addition of alkali on N and P recovery efficiencies. Specifically, two different membrane area ratios (180 and 100 g of N per m2 of membrane) with and without the addition of alkali were studied. High nutrient recovery efficiencies, of 77% for N and 80% for P, were obtained after 10 days of experiment with a ratio of 180 g N per m2 of GPM and the addition of NaOH (1.5 N), along with the precipitant agent (MgCl2) for P precipitation. Hence, a combined configuration was proposed to perform an effective simultaneous recovery of N and P with the minimum amount of membrane needed in a short time., Instituto Nacional de Investigación y Tecnología Agroalimentaria (INIA), Ministerio de Ciencia e Innovación y Agencia Española de Investigación (AEI) - (project PID2019-106148RR-C41), Ministerio de Ciencia e Innovación, Agencia Estatal de Investigación (AEI) y Fondo Europeo de Desarrollo Regional (FEDER) - (Projects RTA2015- 00060-C04-01 and PID2019-106148RR-C41), Ministerio de Ciencia e Innovación, Agencia Estatal de Investigación (AEI) - (grant BES-2017- 082327), Ministerio de Ciencia e Innovación, Agencia Estatal de Investigación (AEI) - (grant RYC-2020-029030-I/AEI/10.13039/501100011033)

Producción Científica, Nowadays, people spend 80–90% of their time indoors, while recent policies on energy efficient and safe buildings require reduced building ventilation rates and locked windows. These facts have raised a growing concern on indoor air quality, which is currently receiving even more attention than outdoors pollution. Prevention is the first and most cost-effective strategy to improve indoor air quality, but once pollution is generated, a battery of physicochemical technologies is typically implemented to improve air quality with a questionable efficiency and at high operating costs. Biotechnologies have emerged as promising alternatives to abate indoor air pollutants, but current bioreactor configurations and the low concentrations of indoor air pollutants limit their widespread implementation in homes, offices and public buildings. In this context, recent investigations have shown that potted plants can aid in the removal of a wide range of indoor air pollutants, especially volatile organic compounds (VOCs), and can be engineered in aesthetically attractive configurations. The original investigations conducted by NASA, along with recent advances in technology and design, have resulted in a new generation of botanical biofilters with the potential to effectively mitigate indoor air pollution, with increasing public aesthetics acceptance. This article presents a review of the research on active botanical filters as sustainable alternatives to purify indoor air., Ministerio de Ciencia e Innovación y Ministerio de Universidades (RTI2018-0096441-B-I00), Junta de Castilla y León - EU-FEDER (CLU 2017–09, CL-EI-2021-07, UIC 315)

Producción Científica, Wastewaters are mainly classified as domestic, industrial and agro-industrial based on their production source. Piggery wastewater (PWW) is a livestock wastewater characterized by its high concentrations of organic matter and ammonium, and by its odour nuisance. Traditionally, PWW has been treated in open anaerobic lagoons, anaerobic digesters and activated sludge systems, which exhibit high greenhouse gas emissions, a limited nutrients removal and a high energy consumption, respectively. Photosynthetic microorganisms can support a sustainable wastewater treatment in engineered photobioreactors at low operating costs and with an efficient recovery of carbon, nitrogen and phosphorous. These microorganisms are capable of absorbing solar irradiation through the photosynthesis process to obtain energy, which is used for their growth and associated carbon and nutrients assimilation. Purple phototrophic bacteria (PPB) represent the photosynthetic microorganisms with the most versatile metabolism in nature, whereas microalgae are the most-studied photosynthetic microorganisms in recent years. This review describes the fundamentals, symmetry and asymmetry of wastewater treatment using photosynthetic microorganisms such as PPB and microalgae. The main photobioreactor configurations along with the potential of PPB and microalgae biomass valorisation strategies are also discussed., Junta de Castilla y León y Fondo Europeo de Desarrollo Regional (FEDER) - (projects CLU 2017-09, CL-EI-2021-07 and UIC 071), Comisión Nacional de Investigación Científica y Tecnológica (CONICYT) de Chile - (PFCHA/DOCTORADO BECAS CHILE/2017–72180211)

Producción Científica, Despite the potential of biogas from waste/wastewater treatment as a renewable energy source, the presence of pollutants and the rapid decrease in the levelized cost of solar and wind power constrain the use of biogas for energy generation. Biogas conversion into ectoine, one of the most valuable bioproducts (1000 €/kg), constitutes a new strategy to promote a competitive biogas market. The potential for a stand-alone 20 L bubble column bioreactor operating at 6% NaCl and two 10 L interconnected bioreactors (at 0 and 6% NaCl, respectively) for ectoine production from biogas was comparatively assessed. The stand-alone reactor supported the best process performance due to its highest robustness and efficiency for ectoine accumulation (20–52 mgectoine/gVSS) and CH4 degradation (up to 84%). The increase in N availability and internal gas recirculation did not enhance ectoine synthesis. However, a 2-fold increase in the internal gas recirculation resulted in an approximately 1.3-fold increase in CH4 removal efficiency. Finally, the recovery of ectoine through bacterial bio-milking resulted in efficiencies of >70% without any negative impact of methanotrophic cell recycling to the bioreactors on CH4 biodegradation or ectoine synthesis., European Union's Horizon 2020 research and innovation program under grant agreement No 837998, European Union's Horizon 2020 research and innovation program and the Bio-based Industries Consortium, Junta de Castilla y León y EU-FEDER (CLU 2017–09, CL-EI-2021–07, UIC 315)

Waste does not exist in nature: the waste of some life forms is the raw material of others. Working in waste management makes it possible to see the great potential contained within residues that still can be extracted. In this line, this thesis is part of a new approach to explore innovative strategies and technologies that allow impacts produced by waste to be minimized, while at the same time recovering its remaining value. This thesis is focused on organic waste from the agro-industrial industry, such as manure and food residues. These wastes have been traditionally managed by using them as organic fertilizers, but it has been stated that this practice can be ineffective, due to nutrient imbalance in the soil and also to potential polluting emissions to the atmosphere, water and soil as result of nutrient losses. Among these emissions, NH3 emissions stand out. These emissions are very harmful to the health of people and animals and to ecosystems. Fortunately, there are some technologies, such as the gas-permeable membrane technology, that are capable of converting these NH3 emissions into a valuable nitrogen based fertilizer that can be used directly on crops. The objective of this thesis is to study different applications of these gas-permeable membranes, and answer the questions that arise in their potential applications. The gas-permeable membrane (GPM) technology has the potential to be applied on different wastewaters to recover nitrogen as a nutrient. This work studies whether the GPM technology can also be applied in existing waste treatment processes, such as biogas plants, where they can not only improve the amount of biogas produced, but also its quality. In addition, it is possible to apply them in the digestate produced by biogas plants, and to obtain high percentages of nitrogen recovery. We have also tested its capability to be combined with other existing techniques for the recovery of other nutrients, such as phosphorus, which is another essentia, Los residuos no existen en la naturaleza: los desperdicios de una especie son la materia prima de otra. Trabajando en la gestión de residuos es posible ver el gran potencial que aún contienen los residuos y que puede ser extraído. En este sentido, esta tesis forma parte de un nuevo abordaje de la investigación para explorar estrategias innovadoras y tecnologías que permiten minimizar los impactos producidos por los residuos, al mismo tiempo que recuperar el valor que contienen. Esta tesis está enfocada en los residuos orgánicos de la industria agro-alimentaria. Estos residuos han sido manejados tradicionalmente como fertilizantes orgánicos, pero recientemente se ha visto que esta práctica puede ser poco efectiva dado que el aporte al suelo de los nutrientes no está bien equilibrado. Asimismo, tienen un gran potencial para generar emisiones a la atmósfera y contaminación de los suelos y del agua debido al exceso de nutrientes que se pueden perder por lixiviación. Entre esas emisiones, el amoniaco (NH3) destaca como un gas particularmente nocivo. Afortunadamente, hay nuevas tecnologías, como la de las membranas permeables a los gases (MPG), que son capaces de convertir esas emisiones de amoniaco en un valioso fertilizante nitrogenado que puede ser aplicado directamente sobre los cultivos. El objetivo de esta tesis es el de estudiar las diferentes aplicaciones de estas MPG y responder a las preguntas que surgen a la hora de su potencial de aplicación. La tecnología de las MPG tiene la capacidad de ser aplicada a diferentes aguas residuales agroindustriales para capturar el NH3 y recuperar el N en forma de nutriente. En este trabajo se ha estudiado que la tecnología de MPG además puede ser combinada con procesos de tratamiento de aguas residuales agro-industriales que ya existen, como las plantas de biogás, donde no sólo han mostrado que mejoran la producción de biogás, sino que además aumentan su calidad. Además, es posible aplicarlas en el digestato resultante de esta, Escuela de Doctorado, Doctorado en Ciencia e Ingeniería Agroalimentaria y de Biosistemas

Producción Científica, Upgrading of biogas to remove siloxanes is mandatory to meet the standards required for its use as a substitute of fossil fuels. The biological degradation of these pollutants is a low cost and environmental friendly alternative to conventional techniques, albeit certain limitations, such as the low solubility of siloxanes, still hinder its application. In the present work, two parameters were optimized in aerobic and anoxic two-phase biotrickling filters (TP-BTF): the trickling liquid velocity (TLV) and the internal gas recirculation, with the aim of improving siloxanes biological removal. The results obtained showed that the increase in TLV from 2 to 10 m h−1 resulted in higher removal efficiency (RE) under both anoxic and aerobic conditions, reaching maximum values of 55 and 47%, respectively. This effect was more significant for the linear siloxanes. On the contrary, a further increase in the TLV to 20 m h−1 together with the implementation of internal gas recirculation caused an excessive turbulence in the liquid side, detaching the biofilm and having a negative effect for the RE. The cyclic siloxanes were more effectively eliminated along the process (maximum REs of 75% were recorded for decamethylcyclopentasiloxane (D5)), but the studied system modifications exerted a minor effect on their RE. The active bacterial population involved in siloxanes degradation (studied throughout RNA extraction and sequencing) was dominated by the clade Acidithiobacillacea KCM-B-112 and the genus Parvibaculum in aerobic conditions, while the members of the family Phyllobacteriacea and the genera Nocardia and Baekduia dominated in anoxic conditions., European Union’s Horizon 2020 research and innovation program under grant agreement No 745785, Junta de Castilla León - EU-FEDER (CLU 2017-09, CL-EI-2021-07 y UIC 315), European Commission-H2020- MSCA-IF-2019 grant (ENHANCEMENT, ref. 897284)

Los procesos biológicos de degradación de compuestos contaminantes constituyen una alternativa económica y de bajo impacto ambiental comparada con las técnicas convencionales. La bioconversión de estos contaminantes en productos valiosos genera un interés aún mayor en el empleo de las biotecnologías. El presente trabajo se centró en el estudio de la biodegradación de compuestos orgánicos volátiles y su bioconversión en sustancias de alto valor farmacéutico y médico empleando las bacterias Halomonas stevensii y Rhodococcus opacus. Los estudios en batch demostraron la capacidad de dichas especies de degradar tolueno, alcanzando rendimientos del 100% y dando lugar a la síntesis de ectoína e hidroxiectoína, evaluada a diferentes concentraciones salinas. Posteriormente se operó un reactor de tanque agitado destinado al mismo objetivo, alcanzando rendimientos de eliminación de tolueno del 42% con Rhodococcus opacus con una salinidad del 3% NaCl y producciones de ectoína e hidroxiectoína de 9,4 mg/L y 2,8 mg/L respectivamente., Biological processes for the degradation of pollutants are an economical alternative with low environmental impact compared to conventional techniques. The bioconversion of pollutants into valuable products generates greater interest in the use of biotechnologies. The present work focused on the study of biodegradation of volatile organic compounds and their bioconversion into substances of high pharmaceutical and medical value using Halomonas stevensii and Rhodococcus opacus. Batch studies demonstrated the capacity of these species to degrade toluene, reaching 100% removal performance and resulting in the synthesis of ectoine and hydroxyectoine, evaluated at different salt concentrations. Subsequently, a stirred tank reactor was operated for the same purpose, achieving toluene removals of 42% with Rhodococcus opacus at 3% NaCl salinity and ectoine and hydroxyectoine concentrations of 9.4 mg/L and 2.8 mg/L, respectively., Departamento de Ingeniería Química y Tecnología del Medio Ambiente, Máster en Ingeniería Ambiental

Producción Científica, The intensification of livestock activities lead to an increase in waste generation with high content of nutrients, as is the case of piggery wastewater. However, this type of residue can be used as culture media for algae cultivation in thin-layer cascade photobioreactors to reduce its environment impact and produce a valorizable algal biomass. Biostimulants were produced by enzymatic hydrolysis and ultrasonication of microalgal biomass, using membranes (Scenario 1) or centrifugation (Scenario 2) as harvesting methods. The co-production of biopesticides by solvent extraction was also evaluated using membranes (Scenario 3) or centrifugation (Scenario 4). The four scenarios were analyzed by a technoeconomic assessment estimating the total annualized equivalent cost and the production cost, i.e., the minimum selling price. Centrifugation provided biostimulants approximately 4 times more concentrated than membranes, but with higher expense due to the cost of the centrifuge (contribution of 62.2 % in scenario 2) and the electricity requirements. The biopesticide production resulted the highest contribution to investment cost in scenarios 3 and 4 (34 % and 43 % respectively). The use of membranes was also more advantageous to produce biopesticides, although it was 5 times more diluted than using centrifuge. The biostimulant production cost was 65.5 €/m3 with membranes and 342.6 €/m3 by centrifugation and the biopesticide production cost was 353.7 €/m3 in scenario 3 and 2,122.1 €/m3 in scenario 4. Comparing the treatment of 1 ha of land, the cost of the biostimulant produced in the four scenarios was lower than the commercial one (48.1 %, 22.1 %, 45.1 % and 24.2 % respectively). Finally, using membranes for biomass harvesting allowed economically viable plants with lower capacity and longer distance for biostimulant distribution (up to 300 km) than centrifuge (188 km). The algal biomass valorization for agricultural products production is an environmentally and economical, Ministerio de Ciencia e Innovación y Ministerio de Universidades (PDC2021-121861-C22, PID2020-113544RB-I00), Ministerio de Ciencia e Innovación y Ministerio de Universidades Doctorate scholarship (PRE2018-083845 and PRE2021-100176), Junta de Castilla y León (UIC 338, CLU 2017-09, CL-EI-2021-07)

Producción Científica, Hydrogen is considered as the future energy vector. Due to scarceness in materials, obtaining hydrogen from common metals and metallic residues is gaining interest. The present work aims at coupling for the first time solvent-based CO2 capture processes with the hydrogen generation from the metal-water splitting reaction, using common elements such as Al, Zn, Mn and Fe. To do so, a novel semicontinuous facility is developed. In the process, both the CO2-Rich stream (CO2RS) and CO2 Capture-Solvent Lean stream (CO2LS) are considered. The production of H2 increased in the order Al < Mn < Fe < Zn. For pure Al, aqueous NaOH (CO2LS) showed the highest H2 yield, up to 85.5%, while Al chips (residue) showed outstanding performance. The experimental study showed that small particle sizes improve the H2 yield. This technology represents an opportunity for bringing about value-added to CO2 capture by generating at the same time green hydrogen., Ministerio de Ciencia e Innovación and Ministerio de Universidades (RTI2018-097456-B-I00), Junta de Castilla y León - FEDER (CLU-2019-04)

Producción Científica, The potential of activated sludge recycling (ASR) and oxidized nitrogen recycling (ONR) to prevent the emissions of H2S and acetic acid from the primary settler during domestic wastewater treatment was herein evaluated. The pilot plant consisted of an 8 L primary settler with a 10 L gas-tight headspace coupled to a 11 L nitrification-denitrification activated sludge reactor and an 8 L secondary settler, which were monitored for 175 days. A reduction in the headspace concentrations of H2S and acetic acid by 95 % and 42 %, respectively, was recorded when combining ASR and ONR. Process operation with ASR and ONR supported stable conditions with average organic matter removals of 96 ± 2 %, NO2- concentrations of 24.2 ± 0.4 mg N/L and NO3- concentrations of 9.8 ± 0.4 mg N/L in the effluent, and a biological oxidation of S2- higher than 99 % with average SO42- concentrations of 52 ± 8 mg/L. Interestingly, the sole recirculation of activated sludge to the primary settler without NO3- recycling caused sludge bulking, contributing to increase the concentration of H2S and acetic acid in the primary settler headspace up to 0.99 ± 0.01 ppmv and 2.87 ± 0.12 ppmv, respectively. Sludge bulking also resulted in an increase in the effluent soluble total nitrogen concentration from 5.6 ± 0.1 mg N/L to 50.8 ± 0.2 mg N/L and of NH4+ from 1.3 ± 0.2 mg N/L to 50.7 ± 0.8 mg N/L due to the loss of nitrification under these operational conditions. Overall, the experimental results indicated that ASR and ONR represent cost-effective strategies for the control of malodorous emissions in wastewater treatment plants., Junta de Castilla y León - EU-FEDER (CLU 2017-09, CL-EI-2021-07 y UIC 315), Ministerio de Ciencia e Innovación (FJC2019-039791-I)

Producción Científica, Despite the interest in the utilization of photobioreactors as an alternative wastewater treatment, the research about posterior recovery and valorization of nutrients accumulated in the biomass is still limited. This work compared several hydrolysis methods for the recovery of proteins and carbohydrates from the biomass grown in a photobioreactor treating swine wastewater. Ultrasound-assisted and microwave-assisted enzymatic hydrolysis at mild conditions and chemical methods at different temperatures (40, 60, 120ºC) were applied to the microalgae and bacteria biomass. Alkaline hydrolysis provided the greatest peptide recoveries, increasing with temperature up to a maximum of 81%, but with very small peptide sizes in all temperature range. Acid hydrolysis provided the highest carbohydrate recoveries (60.7% at 120ºC) but degraded proteins, even at mild temperatures. Protein degradation did not vary with temperature in each chemical hydrolysis, obtaining similar peptide sizes in all temperatures, while carbohydrate losses were higher at lower temperatures. Ultrasound-assisted enzymatic extraction recovered 43.6% of the initial proteins as large peptides (up to 135 kDa) with the highest peptide purity (46.7%). Microwave-assistance increased the carbohydrate solubilization of enzymatic hydrolysis, achieving yields of 73% of xylose, but with significant losses., Ministerio de Ciencia e Innovación y Ministerio de Universidades (PID2020-113544RB-I00 y PDC2021-121861-C22), Junta de Castilla y León (UIC 338, CLU 2017-09), UE-FEDER (CLU 2017-09)

Producción Científica, To recover industrial pectin from sugar beet pulp (SBP), a combined surfactant and ultrasound-assisted extrac- tion, followed by a concentration with ultrafiltration/diafiltration membranes is proposed. First, the operation conditions of the extraction were optimized for synthetic (Tween80, PEG4000) and natural (Saponin) surfac- tants. Tween 80 and Saponin provided maximum galacturonic acid (GalA) concentrations (5.5 and 5.8 g/L, respectively) under the best extraction conditions (4 gsurfactant/L, pH = 1, amplitude = 90%, and time = 90 min). The extracted liquid was purified and concentrated through membranes. The final retentate maintained 73% of the initial GalA and eliminated a high percentage of oligosaccharides. Finally, the pectin was precipitated with ethanol, and the precipitate solid contained 57 g GalA/100 g GalA of SBP with a high degree of esterification (DE = 81%) and MW (930 kDa). The pectin yield for the global process was 24.6%. The ultrasound-assisted extraction with surfactants followed by diafiltration/ultrafiltration could become a promising process for the chemical industry, able to provide pectin-enriched products of commercial interest from sugar beet pulp., Ministerio de Ciencia e Innovación (Proyecto PID2020–115110RB-I00/ AEI/10.13039/501100011033), Junta de Castilla y León (UIC 320, VAG028G19, CLU-2017–09, CL-EI-2021–07), Junta de Castilla y Leon (postdoctoral grant E-47–2019-0114592)

Producción Científica, The effect of hydraulic retention time (HRT) on the continuous lactate-driven dark fermentation (LD-DF) of food waste (FW) was investigated. The robustness of the bioprocess against feast/famine perturbations was also explored. The stepwise HRT decrease from 24 to 16 and 12 h in a continuously stirred tank fermenter fed with simulated restaurant FW impacted on hydrogen production rate (HPR). The optimal HRT of 16 h supported a HPR of 4.2 L H2/L-d. Feast/famine perturbations caused by 12-h feeding interruptions led to a remarkable peak in HPR up to 19.2 L H2/L-d, albeit the process became stable at 4.3 L H2/L-d following perturbation. The occurrence of LD-DF throughout the operation was endorsed by metabolites analysis. Particularly, hydrogen production positively correlated with lactate consumption and butyrate production. Overall, the FW LD-DF process was highly sensitive but resilient against transient feast/famine perturbations, supporting high-rate HPRs under optimal HRTs., European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 894515, MCIN/AEI /10.13039/501100011033 - Unión Europea NextGenerationEU/PRTR (Grant RYC2021‐034559‐I), Junta de Castilla y León - EU-FEDER (CLU 2017-09, CL-EI-2021-07 y UIC 315)

Producción Científica, The influence of membrane-based ammonia extraction on poultry manure (PM) wastewater treatment was assessed in a 3 L continuous stirred tank reactor (CSTR). The anaerobic digester operated for 91 days at a hydraulic retention time of 15 days and 37 °C. The flat sheet polytetrafluoroethylene (PTFE) membrane module was interconnected to the CSTR and operated at a recirculation flow rate of 0.25 L min−1. The membrane-based ammonia extraction mediated a decrease of total ammonia nitrogen of 64.5 % and of total nitrogen of 53.4 %, which induced an increase in the methane yields from 360 ± 70 up to 574 ± 5 N mL CH4 g VS fed−1. Similarly, chemical oxygen demand (COD) and volatile solids (VS) removal efficiencies increased from 59 % ± 2 % and 57 % ± 3 % up to 79.1 % ± 0.8 % and 65.8 % ± 0.2 %, respectively. This work targeted the enhancement of the performance of full-scale anaerobic digestion plants via reduction of NH3 concentration with a membrane-based extraction unit., Junta de Castilla y León - FEDER (VA088G19, CL-EI-2021-07, UIC 315 y UIC 082), Ministerio de Ciencia e Innovación - AEI (PID2019-109403RB-C21)

Producción Científica, The textile industry generates millions of tons of waste annually, making this sector one of the most polluting in the world. The objective of this research was to study the energy potential of three industrial textile wastes of vegetable and animal origin: CW (card waste), SFW (short fibre waste) and W (wool), using conventional and flash pyrolysis at 500 °C and 750 °C. CW and SFW thermogravimetric profiles were very different from W. In general, the bio-oil yield was higher in the conventional and in the low-temperature flash pyrolysis (up to 55 %). The gas obtained by flash pyrolysis at 750 °C has higher flue gas content and lower CO2 content so their high heating value (HHV) is higher (up to 15.34 MJ/kg). Bio-oils obtained by flash pyrolysis at high temperature stood out for their higher HHV (>30 MJ/kg), with the highest value (34.15 MJ/kg) obtained from SFW waste. Both low temperature flash pyrolysis and conventional pyrolysis produce bio-oils that contain aromatic (35–48 %) and non-aromatic (18–34 %) organic compounds. Additionally, they have high levels of phenols and benzenes. High-temperature flash pyrolysis bio-oils are mainly composed of polycyclic aromatic hydrocarbons. The textile samples are suitable for an energetic valorisation, highlighting the best SWF behaviour., Consejo Superior de Investigaciones Científicas (CSIC) grant JAE INTRO ICU SCHOLARSHIP 2019 [Ref. JAEICU-19-INCAR-15], Agencia Estatal de Investigación (AEI) and (UE) projects (PDC2022-133394-I00) and (PID2021-124347OB-I00)

Producción Científica, BACKGROUND The microalgal-bacterial systems work on the principle of the symbiotic relationship between algae and bacteria. The ability of algal-bacterial photobioreactors for the treatment of wastewater containing ammonia and phenol has been poorly addressed. In this work a self-sustaining synergetic microalgal-bacterial granular sludge process was thus developed to treatment of industrial wastewater based upon the low cost of photosynthetic oxygenation and the simultaneous phenol and nitrogen removal. The performance of a conventional sequential batch reactor (SBR) based on aerobic bacterial communities (SBRB) and a microalgal-bacterial granular SBR (SBRMB) were comparatively assessed. The major challenges associated with microalgal-bacterial systems have been discussed. RESULTS A complete removal of phenol (100 mg L-1) was achieved in both reactors. The reactors SBRB and SBRMB showed similar performance in term of removal of inorganic nitrogen. Nitrogen mass balances estimated nitrogen assimilation, nitrification and denitrification. Higher simultaneous nitrification and denitrification (70% SND) occurred in SBRB as determined by mass balances. The higher nitrogen assimilation (17.9%) by the microalgal-bacterial biomass compensated the lower denitrifying activity in SBRMB (54% SND), resulting in a removal of inorganic nitrogen (61%) similar to that obtained in SBRB (66%). N2O was not detected in the headspace of any system. CONCLUSIONS Granular microalgae-bacterial consortia implemented in SBR constitute an efficient method for industrial wastewater treatment achieving complete removal of ammonia and phenol. The application of SBRMB would be more cost-effective than SBRB mainly due to the significant energy savings in SBRMB resulting in a sustainable system that contributes to the circular bioeconomy., Junta de Castilla y León y la UE-FEDER (grant numbers CLU 2017-09, CL-EI-2021-07 and UIC 315)

Producción Científica, Sample preparation for the analysis of organic micropollutants in wastewater samples is commonly carried out by solid-phase extraction (SPE) procedures, which involve different manual laboratory operations. This conventional approach requires several hours of counter labour and entail the use of a lot of disposable material, and the subsequent contaminated non-recyclable plastic-residue production. In contrast, by coupling and automatizing the pre-treatment to the instrumental analysis most of that burden erases, sample size gets miniaturized and, thus, storage becomes freed-up. Even lab counters get cleared off from sample pre-treatment apparatus. However, method performance could get alter as a trade-off. This paper presents the results from a study in which methodology, including SPE online-coupled to UHPLC-MS/MS chromatography, was developed for multi-residue (58) determination of veterinary and pharmaceutical drugs in urban and piggery wastewater (influent and effluent to wastewater treatment plants (WWTPs)). Similarly, the direct injection (DI) of large volumes (hundreds of µL) of same matrix samples into the chromatographic system was optimized too. The performance of both automated methods was statistically compared with the classical off-line SPE. As dealing with trace analysis, suitable injection volumes for the alternative approaches were selected on the premise of low limits of quantification (MLQs). Under the selected conditions, validation parameters such as linearity range, method quantification limits, peak shape and carry over were determined. Usually more than 50 % of the analytes showed MLQs below 50 ng/L, for all matrices and methodologies, especially for DI. Real wastewater samples from a local urban WWTP and farm were analysed with all three tested methodologies. Determined concentrations and removal rates were statistically compared and turned out being quite similar. However, analysis under offline SPE and DI approaches provided a larger amou, Junta de Castilla y León, y el programa EU-FEDER (CLU 2017-09),(CL-EI-2021-07),(UIC 071),(UIC 338),(INFRARED2018-UVA3)., Ministerio de Ciencia, Innovación y Universidades (proyectos CTQ2017-84006-C3-1-R y PID2020-113544RB-I00)

Producción Científica, Scenedesmus almeriensis microalgae-bacteria consortia were evaluated for the removal of a mixture of tetracycline (TET), ciprofloxacin (CIP), and sulfadiazine (SDZ) from the real liquid fraction of pig slurry in a pilot scale photobioreactor. After 15 days of operation, the reactor was spiked with a mixture of /L of each antibiotic. The experiment ran for 20 additional days. From the liquid phase, antibiotic removal were 77 ± 5 %, 90 ± 14 %, and 60 ± 27 % for TET, CIP, and SDZ, respectively. The antibiotics found in the solid phase were 979 ± 382 ng/g for TET and 192 ± 69 ng/g for SDZ; CIP was not detected in the biomass. The parameters analyzed before and after antibiotic addition showed that the antibiotics did not have a negative effect on the reactor biomass. The removal efficiencies of the analyzed parameters were 64.6 ± 0.6 % for TOC, 56.9 ± 0.6 % for IC, 63.9 ± 0.6 % for TN, 88.6 ± 0.9 % for N-NH, 64.9 ± 0.6 % for N-NO, and 30.1 ± 0.3 % for P-PO. This study demonstrated the good performance of microalgae-based technology for swine manure wastewater treatment, not only in terms of organic matter and nutrient removal, but also regarding the removal of antibiotics. The mass balance analysis of the entire process is presented. Additionally, the present study is a validation of previous laboratory scale batch studies operating in a quasi-continuous mode on veterinary antibiotics (VA) removal efficiencies and kinetics., Junta de Castilla León (UIC 071, CLU 2017-09 y VA080G18), Ministerio de Ciencia e Innovación y Ministerio de Universidades (PID2020-113544RB-I00, PDC2021-121861-C22), EU-FEDER (CLU 2017-09, CL-EI-2021-07, UIC 315)

Producción Científica, Assessing carbon efficiency (CE) in the provision of drinking water services is essential to achieve a net-zero greenhouse gas (GHG) urban water cycle. Previous studies evaluating the CE of water companies are very scarce and employed parametric and non-parametric. Both methodological approaches present limitations such as overfitting issues or require assumptions about the production technology which could lead to less reliable efficiency scores. To overcome these limitations, in this study, and for the first time, we estimated CE of English and Welsh water companies using the Efficiency Analysis Trees (EAT) approach. This technique brings together machine learning and non-linear programming techniques to estimate production frontier and efficiency scores. It also allowed us to quantify the optimal level of GHG emissions in the provision of water services and estimate potential GHG savings. Bootstrap truncated regression methods were employed to quantify the impact of operating characteristics on CE of water companies. The optimal level of GHG emissions was estimated to be between 0.062 and 133.03 tons of CO2 equivalent (CO2eq) per year and per connected property. The average CE was at the level of 0.632. This means that GHG emissions could reduce by 36.8% to maintain the same level of water services. Equivalently, this corresponds to a reduction of 488,321 tons of CO2eq per year. Water only companies exhibited a better performance than water and sewerage companies with an average CE of 0.785 and 0.540, respectively. The performance of the English and Welsh water companies decreased over time. In 2011 the average CE was 0.772 whereas it went down to 0.534 in 2020. It was also estimated that on average water companies could reduce 0.034 tons of CO2eq per cubic meter of drinking water supplied and 16.16 tons of CO2eq/ connected property per year. The regression results showed that topography and water treatment complexity had a significant impact on CE. The conclusio

Producción Científica, Wastewater treatment plants (WWTPs) are energy intensive facilities. Controlling energy use in WWTPs could bring substantial benefits to people and environment. Understanding how energy efficient the wastewater treatment process is and what drives efficiency would allow treating wastewater in a more sustainable way. In this study, we employed the efficiency analysis trees approach, that combines machine learning and linear programming techniques, to estimate energy efficiency of wastewater treatment process. The findings indicated that considerable energy inefficiency among WWTPs in Chile existed. The mean energy efficiency was 0.287 suggesting that energy use should cut reduce by 71.3 % to treat the same volume of wastewater. This was equivalent to a reduction in energy use by 0.40 kWh/m3 on average. Moreover, only 4 out of 203 assessed WWTPs (1.97 %) were identified as energy efficient. It was also found that the age of treatment plant and type of secondary technology played an important role in explaining energy efficiency variations among WWTPs., Junta de Castilla y León - UE-FEDER (CLU 2017-09, CL-EI-2021-07)