High added-value compounds from the integral revalorisation of winery residues

258 p.El sarmiento es un residuo vitivinícola generado en grandes cantidades y que carece de aplicaciones de valor añadido. Su aprovechamiento podría aumentar los beneficios económicos de esta actividad y reducir los problemas medioambientales asociados a su actual empleo. Para dar solución a esta problemática, en esta tesis se planteó su revalorización integral aplicando el concepto de biorrefinería. Para ello, se llevó a cabo un pre-tratamiento de autohidrólisis que permitió la solubilización de la fracción hemicelulosica y la obtención de oligosacáridos con actividad prebiótica que podrían emplearse como ingredientes alimenticios y de extractos bioactivos con aplicaciones como antioxidantes y antimicrobianos. En una segunda etapa, se buscó separar la celulosa y la lignina presentes en el sólido obtenido tras la autohidrólisis. Para esta finalidad, se llevaron a cabo diferentes tratamientos de deslignificación, resultando ser el tratamiento alcalino el más eficaz, permitiendo a su vez la obtención de ligninas de elevada pureza y de un sólido con un alto contenido en celulosa que mostró una alta susceptibilidad a la hidrólisis enzimática. La asistencia del tratamiento de deslignificación alcalina con microondas, permitió aumentar la eficacia y reducir el tiempo de tratamiento. El análisis del Ciclo de Vida de las rutas de biorrefinería propuestas mostró que a mayor número de procesos mayores requerimientos energéticos y en consecuencia peores perfiles ambientales se obtiene

High added-value compounds from the integral revalorisation of winery residues

258 p.El sarmiento es un residuo vitivinícola generado en grandes cantidades y que carece de aplicaciones de valor añadido. Su aprovechamiento podría aumentar los beneficios económicos de esta actividad y reducir los problemas medioambientales asociados a su actual empleo. Para dar solución a esta problemática, en esta tesis se planteó su revalorización integral aplicando el concepto de biorrefinería. Para ello, se llevó a cabo un pre-tratamiento de autohidrólisis que permitió la solubilización de la fracción hemicelulosica y la obtención de oligosacáridos con actividad prebiótica que podrían emplearse como ingredientes alimenticios y de extractos bioactivos con aplicaciones como antioxidantes y antimicrobianos. En una segunda etapa, se buscó separar la celulosa y la lignina presentes en el sólido obtenido tras la autohidrólisis. Para esta finalidad, se llevaron a cabo diferentes tratamientos de deslignificación, resultando ser el tratamiento alcalino el más eficaz, permitiendo a su vez la obtención de ligninas de elevada pureza y de un sólido con un alto contenido en celulosa que mostró una alta susceptibilidad a la hidrólisis enzimática. La asistencia del tratamiento de deslignificación alcalina con microondas, permitió aumentar la eficacia y reducir el tiempo de tratamiento. El análisis del Ciclo de Vida de las rutas de biorrefinería propuestas mostró que a mayor número de procesos mayores requerimientos energéticos y en consecuencia peores perfiles ambientales se obtiene

Acid Hydrolysis of Almond Shells in a Biphasic Reaction System: Obtaining of Purified Hemicellulosic Monosaccharides in a Single Step

The aim of this work is to comprehend the biphasic reaction systems through another perspective; the simultaneous purification and production of carbohydrates during the pretreatment of biomass. A dilute acid hydrolysis of almond shells in a 2-Methyltetrahydrofuran/H2O system was optimised to maximise the obtaining of hemicellulose-derived monosaccharides with the minimum formation of degradation products. The optimised conditions of the biphasic reaction system, which produced 205.3 g hemicellulose-derived monosaccharides/Kg almond shells, were replicated in a monophasic reaction system to assess the benefits of the biphasic reaction systems. The latest system allowed the removal of 85.3% of the furans generated during the dilute acid hydrolysis, creating antioxidant extract, together with the catalysis of the hydrolysis of the hemicelluloses in a 20%. Therefore, the proposed process could become a promising method to purify carbohydrates with an environmentally friendly procedure that allowed the obtaining of multiple added-value products in a single step.Dr. I. Dávila would like acknowledge to the University of the Basque Country (UPV/EHU) for the financial support (Grant reference No. DOCREC19/47

Cross-Linked Carboxymethylcellulose Adsorbtion Membranes from Ziziphus lotus for the Removal of Organic Dye Pollutants

The goal of this study is to assess Ziziphus lotus’s potential for producing carboxymethylcellulose adsorption membranes with the ability to adsorb methyl green from wastewaters by the revalorization of its cellulosic fraction. The cellulose from this feedstock was extracted by an alkaline process and TAPPI standard technique T 203 cm-99 and afterwards they were carboxymethylated. The obtained carboxymethylcelluloses were deeply characterized, being observed that the carboxymethylcellulose produced from the alkaline cellulose presented the higher solubility due to its lower crystallinity degree (53.31 vs. 59.4%) and its higher substitution degree (0.85 vs. 0.74). This carboxymethylcellulose was cross-linked with citric acid in an aqueous treatment in order to form an adsorption membrane. The citric acid provided rigidity to the membrane and although it was hydrophilic it was not soluble in water. By evaluating the potential of the produced membrane for the removal of pollutant dyes from wastewater, it was observed that the adsorption membrane prepared from the carboxymethylcellulose’s produced from the Ziziphus lotus was able to remove 99% of the dye, methyl green, present in the wastewater. Thus, this work demonstrates the potential of the Ziziphus lotus for the production of a novel and cost-effective carboxymethylcellulose adsorption membrane with high capacity to treat wastewaters.This research was funded by Ministry of Higher Education and Scientific Research of Tunisia, I. Dávila would like to thank the University of the Basque Country (UPV/EHU) for their financial support (Grant reference DOCREC19/47)

Life Cycle Assessment of various biorefinery approaches for the valorisation of almond shells

In the near future, sustainable and efficient biorefineries would be essential for the production of commodity chemicals and high-added value compounds. Therefore, in this work, six scenarios differing on the delignification steps and cellulose conversion routes were assessed via Life Cycle Assessment methodology in order to study the environmental impacts derived from the conversion of an abundant agricultural residue (almond shells) into high added-value products and select the most suitable one for large-scale valorisation. The assessments were conducted employing experimental results and processing them by SimaPro software. The main conclusion achieved suggested that the enzymatic hydrolysis of the solid from any delignification step entailed the highest environmental impacts and had the highest relative contribution in all the studied impact categories with a maximum of 74%, which was ascribed to Scenario 5. It was also concluded that the organosolv delignification process affected overall more negatively than the alkaline treatment having bigger impacts especially in abiotic depletion (ADP) and photochemical oxidation (POP) categories. Finally, it can be stated that the best route for valorising the almond shell in a biorefinery facility is composed of autohydrolysis (common for every scenario), alkaline delignification, bleaching and acid hydrolysis steps for the obtaining of oligosaccharides, lignin and nanocrystals as products.Authors want to acknowledge the University of the Basque Country UPV/EHU, as well as the Spanish Ministry of Science and Innovation (CTQ2016-78689-R) for supporting financially this research. L.S. and R.F. would like to acknowledge the Departmentof Economic Development and Infrastructures of the Basque Government (scholarship of young researchers training) . A.M. and I.D, would like to thank the University of the Basque Country (Training of Researcher Staff, PIF17/207 and grant reference DOCREC19/47, respectively)