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This article refers to the chemical recovery of cellulose from fabrics composed of Cotton (CO)/Polyester (PES) achieved using Ionic Liquids (ILs). Initially, the effect of ionic liquids on the surface of the textile is analyzed, determining the influencing factors related to the entry of IL inside the textile and the chemical mechanism that controls the system. This work considers the influence of the time, ratio, and temperature variables on the system, with the aim of defining which of them has a greater influence on the process. The ability of ionic liquids, specifically 1-Allyl-3-Methylimidazolium Chloride (AmimCl), to dissolve cellulose and subsequently regenerate the material through a simulation of the wet spinning process is evaluated. The responsible for the fiber’s inflation, water or DMSO, has also been another factor of study, analyzing the influence of each solvent and the interactions when in contact with the ionic liquid. Finally, the regenerated substance is characterized by its surface structure using the Scanning Electron Microscope (SEM), its molecular structure by Infrared Spectroscopy Analysis (FTIR), and its thermal stability by Thermogravimetric Analysis (TGA) Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura

Biodegradation of polyesters driven by enzymes is considered as one of the most effective way of degradation of these materials, as a way to control plastics accumulation in the environment. In this study, we present two different strategies to tune the enzymatic degradation of PBS films triggered by a lipase from Pseudomonas cepacia. Firstly, the kinetics of enzymatic degradation of PBS films was regulated by applying multilayer coats of polysaccharide alginate and chitosan (Alg/Chi) films. Secondly, self-degradable PBS films were prepared by embedding lipase-filled alginate particles. For comparison purposes, a detailed enzymatic degradation study of neat PBS films exposed to a lipase from P. cepacia in solution was made to determine the main experimental parameters influencing their degradation in solution. The results showed that an increase in enzyme concentration increased the degradation extent and rate of neat PBS films. At a fixed enzyme concentration, stirring of the solution containing the enzyme and the PBS also increased the biodegradation rate. In the case of the PBS films coated with a different number of Alg/Chi layers by spray-assisted LbL and subjected to enzymatic degradation experiments in solution, the extent of degradation was found to be dependent on the number of protective coating layers. Therefore, the Alg/Chi biobased coating constitutes an effective barrier to the diffusion of the lipase, thus proving its effectiveness in modulating the enzymatic activity as a function of coating thickness. In the case of self-degradable PBS containing lipase-embedded alginate beads (employed to protect the enzyme during high-temperature processing), only limited biodegradation was observed as the amount of encapsulated enzyme employed was too small. Nonetheless, these results are promising, as the enzymatic activity –indicative of the degradation capacity of the enzyme– determined for all these samples was about 2 orders of magnitude lower than that of previous assays., This research was funded by the projects MAT2017-83014-C2-1-P, MAT2017-83014-C2-2-P, PID2020-113045GB-C21 and PID2020-113045GB-C22 funded by MCIN/ AEI /10.13039/501100011033 and by the Basque Government through grant IT1503-22. We would also like to acknowledge the financial support from the BIODEST project; this project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie grant agreement No. 778092. M.I.P. is supported with an FPI contract (PRE2018-086104) to develop a PhD thesis. R.H. is member of the CSIC Interdisciplinary Thematic Platform (PTI+) Interdisciplinary Platform for Sustainable Plastics towards a Circular Economy+ (PTI-SusPlast+). J.M.R. is a FRS-FNRS Senior Research Associate. Authors would also like to thank Dr. Ana Beloqui for helpful discussions on enzymatic activity.

El consum de tèxtil per habitant creix de manera exponencial, de manera que, el desenvolupament de nous processos sobre la gestió i els tractaments de residus tèxtils resulta una oportunitat clau per aconseguir models integrals d’economia circular que assegurin el tancament dels cicles. Actualment, es calcula que aproximadament un 80% dels residus tèxtils generats estan constituïts per fibres de cotó (CO) i polièster (PES). L’heterogeneïtat en els residus tèxtils és tot un repte per a la indústria tèxtil, per la qual cosa en aquest projecte s’estudia la recuperació de la cel·lulosa provinent de teixits PES/CO a partir de l’ús de líquids iònics (ILs). Inicialment s’analitza l’efecte dels líquids iònics sobre la superfície del teixit, determinant els factors influents referents a l’entrada del IL a l’interior del teixit i el mecanisme químic que governa el sistema. En aquest projecte es contempla l’estudi de les variables de temps, ràtio i temperatura del sistema, amb l’objectiu de definir quina d’elles té una major influència sobre el procés. S’avalua la capacitat dels líquids iònics, en concret de l’AmimCl, per a dissoldre la cel·lulosa i posteriorment regenerar la matèria mitjançant una simulació del procés wet spinning. El medi d’inflament de la fibra, aigua o DMSO, també ha estat un altre factor estudiat, examinant així la influència de cada dissolvent i les interaccions quan entren en contacte amb el líquid iònic. Finalment, de la matèria regenerada es caracteritza la seva estructura superficial a partir del microscopi electrònic d’escombratge (SEM), la seva estructura molecular mitjançant un anàlisis d’espectroscòpia infraroja (FTIR) i la seva estabilitat tèrmica amb un anàlisi termogravimètric (TGA). El consumo de textil por habitante crece de manera exponencial, de manera que, el desarrollo de nuevos procesos sobre la gestión y los tratamientos de residuos textiles resulta una oportunidad clave para conseguir modelos integrales de economía circular que aseguren el cierre de ciclos. Actualmente, se calcula que aproximadamente un 80% de los residuos textiles generados están constituidos por fibras de algodón (CO) y poliéster (PES). La heterogeneidad en los residuos textiles es todo un reto para la industria textil, por lo que en este proyecto se estudia la recuperación de la celulosa proveniente de tejidos PES/CO a partir del uso de líquidos iónicos (ILs). Inicialmente se analiza el efecto de los líquidos iónicos sobre la superficie del tejido, determinando los factores influyentes referentes a la entrada del IL en el interior del tejido y el mecanismo químico que gobierna el sistema. En este proyecto se contempla el estudio de las variables de tiempo, ratio y temperatura del sistema, con el objetivo de definir cuál de ellas tiene una mayor influencia sobre el proceso. Se evalúa la capacidad de los líquidos iónicos, en concreto del AmimCl, para disolver la celulosa y posteriormente regenerar la materia mediante una simulación del proceso wet spinning. El medio de inflamiento de la fibra, agua o DMSO, también ha sido otro factor estudiado, examinando así la influencia de cada disolvente y las interacciones cuando entran en contacto con el líquido iónico. Finalmente, de la materia regenerada se caracteriza su estructura superficial a partir del microscopio electrónico de barrido (SEM), su estructura molecular mediante un analisis de espectroscopia infrarroja (FTIR) y su estabilidad térmica con un analisis termogravimétrico (TGA). Textile consumption per inhabitant is growing exponentially, and therefore the development of new processes related to the management and treatment of textile waste is a key opportunity to achieve comprehensive circular economy models that ensure the closure of cycles. Nowadays, it has been estimated that approximately an 80% of the textile waste generated is composed of cotton (CO) and polyester (PES) fibers. The heterogeneity in the textile waste is a huge challenge for the textile industry, and for this reason this project studies the recovery of cellulose coming from textile fabrics composed of PES/CO making use of ionic liquids (ILs). Initially, the effect of ionic liquids on the surface of the textile is analyzed, determining the influencing factors related to the entry of IL inside the textile and the chemical mechanism that controls the system. This project considers the study of the time, ratio, and temperature variables of the system, with the aim of defining which of them has a greater influence on the process. The ability of ionic liquids, specifically AmimCl, to dissolve cellulose and subsequently regenerate the material through a simulation of the wet spinning process is evaluated. The responsible for the fiber’s inflation, water or DMSO, has also been another factor of study, analyzing the influence of each solvent and the interactions when in contact with the ionic liquid. Finally, the regenerated substance is characterized by: its surface structure using the scanning electron microscope (SEM), its molecular structure by infrared spectroscopy analysis (FTIR) and its thermal stability by thermogravimetric analysis (TGA).

[eng] Rapid population growth is leading to many environmental problems, among which a large waste generation should be highlighted. More than 40% of these wastes correspond to organic wastes that are mainly treated by composting, anaerobic digestion, incineration, or even landfilled. Hence, it is important to implement new treatment strategies within the circular economy concept transforming organic waste treatment plants into biorefineries. In this way, acidogenic fermentation emerges as a key technology to valorise these substrates producing high value- added products such as volatile fatty acids (VFAs), that could be further transformed into bioplastics (i.e., polyhydroxyalkanoates or PHA). Consequently, acidogenic fermentation and co-fermentation of waste activated sludge (WAS) and food waste (FW) were studied to achieve a VFA-rich effluent for its subsequent conversion into PHA. The pH effect on the acidogenic fermentation of FW was studied in batch mode (pH range from 4 to 11) and in semi-continuous fermenters working under acidic (6) and alkaline pH (9.5-10). Batch tests revealed that pH between 6-9 could lead to a higher VFA production, with a higher acetic acid content when pH increased within this range. In the semi-continuous fermenters, a maximum VFAs yield of 503.1 mgCOD/gVS was obtained when working at pH 6 with acetic, butyric and caproic acids as majoritarian VFAs, while at pH 10, a lower yield (315.1 mgCOD/gVS) was obtained with acetic as the main acid. WAS and FW co-fermentation was explored (50%, 70% and 90% WAS on VS basis), demonstrating the benefits, since a higher fermentation yield was obtained in WAS/FW co-fermentation assays compared to WAS or FW mono-fermentation. In all mixtures tested, the buffer capacity of WAS was enough to maintain the pH above inhibitory levels without reagents addition. Moreover, when the proportion of FW in the WAS/FW was raised, more butyric and less propionic acid was produced achieving a maximum fermentation yield of 480 mgCOD/gVS when the mixture was 50%FW+50%WAS. Since the effect of each FW fraction has been barely studied, discontinuous assays using diverse FW fractions were also performed. The principal components analysis (PCA) revealed the relation between each fraction and each fermentation profile. Furthermore, these assays were essential to understanding the importance of balancing the protein-to-carbon ratio to achieve a maximum VFA yield of about 500 mgCOD/gVS. WAS and FW co-fermentation was studied under long-term conditions in semi-continuous fermenters at several organic loading rates (OLR). This study demonstrated the importance of microorganisms’ immigration with the feed substrates and their adaptation in semi-continuous processes. The stages carried out at OLR 9 and 11 gVS/(L·d) obtained lower VFAs yields probably due to the methanogenic activity favoured at the neutral pH. However, when higher OLR were applied (14 and 18 gVS/(L·d)), the pH started to decrease with a concomitant increase on the VFA yield until achieving a maximum of 475 mgCOD/gVS, with butyric as the main acid. Moreover, this study demonstrates that not only the FW properties and its proportion affect the obtained VFA yield and distribution on co-fermentation, but also the WAS characteristics are important, especially when the pH is low, and the buffering capacity could avoid a sudden drop in the pH. Finally, the start-up and operation of a sequencing batch reactor (SBR) to select PHA-storing microorganisms was performed using a VFA-rich feeding with an OLR of 2.0 and 2.8 gCOD/(L·d). The biomass selection was carried out with a double growth limitation strategy (feast/famine and uncoupled carbon and nitrogen feeding). The successful selection of PHA-storing biomass was confirmed in batch accumulations assays where VFA pulse feeding strategy was used obtaining a PHA content between 44 and 46% (on SS basis) with polyhydroxybutyrate (PHB) as the main component., [spa] El gran crecimiento poblacional está comportando una gran generación de residuos que necesitan ser tratados de la mejor manera posible. Por ello, la Unión Europea propone implementar nuevas estrategias de tratamiento de residuos dentro del concepto de economía circular mediante la transformación de las plantas de residuos en biorrefinerías, donde los residuos son concebidos como productos. En este sentido, el proceso de fermentación acidogénica emerge como una tecnología clave para valorizar los sustratos orgánicos en forma de productos de alto valor añadido como son los ácidos grasos volátiles (AGVs) que pueden ser usados para la producción de bioplásticos (polihidroxialcanoatos o PHA). Los residuos alimentarios y los fangos activos de las depuradoras son los residuos orgánicos más generados en las zonas urbanas. Actualmente son tratados por separado, pero debería contemplarse su tratamiento conjunto ya que resultaría beneficioso debido a las sinergias que se formarían. Por este motivo, la presente tesis se basa en el estudio de la fermentación acidogénica de estos residuos por separado, así como su tratamiento conjunto (co-fermentación) con el fin de generar un efluente rico de AGVs para su posterior conversión en PHA. Para ello, se llevaron a cabo estudios en discontinuo y en semi-continuo para comprobar el efecto del pH en la fermentación de los residuos alimentarios viendo que tiene un papel crucial. Seguidamente, se estudió la co-fermentación de fangos activados con los residuos alimentarios en diferentes proporciones. Este estudio demostró que la capacidad tampón del fango era suficiente para sostener el pH por encima de los niveles inhibitorios. Asimismo, se mostraron sinergias al co-fermentar estos residuos con producciones mayores que mono-fermentando, viendo que la proporción de cada residuo afectaba a la producción y perfil de los AGVs. Además, también se estudió la relación entre cada fracción de los residuos alimentarios y el perfil de producción de ácidos. También se comparó el efecto de trabajar en discontinuo y semi-continuo viendo que tenía importantes efectos debido a la inmigración y adaptación de los microorganismos. Finalmente, se estudió la viabilidad de producir PHA usando un efluente sintético rico en AGVs obteniendo unos buenos porcentajes de acumulación del biopolímero.