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El sistema de centrifugación bifásico para la extracción del aceite de oliva, genera un único subproducto denominado alperujo que, debido a sus características fisicoquímicas se convierte en un desecho poco amigable para el medio ambiente. El sudoeste de la provincia de Buenos Aires (SOB) constituye una nueva área de producción olivícola, con importante intensificación de la actividad, que impulsa la necesidad de analizar opciones para su reutilización. En esta Tesis se plantea la reconversión del alperujo, como sustrato de bajo costo para la producción de pigmentos carotenoides. Para tal fin, se evaluaron levaduras del género Rhodotorula (Rh. mucilaginosa LPSC 638, Rh. graminis Y52 y Rh glutinis Y54). En primer lugar, se prepararon y caracterizaron diferentes medios derivados del alperujo: Extractos acuosos (EAs) de diferentes concentraciones (5, 10, 20 y 30 % p/V) y la fracción líquida del alperujo (AA). Por otra parte, se desfenolizaron los medios con mayor concentración de biofenoles (EA 30% y AA), mediante la técnica partición líquido-líquido. Todos estos medios, se utilizaron para evaluar el desarrollo y la biosíntesis de carotenoides en Rh. mucilaginosa LPSC638. Asimismo, se evaluó la influencia del inhibidor Imidazol en su vía carotenogénica. También, se estudió el metabolismo de la levadura asociado a fuentes de C y N. Al mismo tiempo, se realizaron ensayos de fitotoxicidad en EAs y AA normales y desfenolizados, sobre semillas de Lactuca sativa L. En segundo lugar, se analizó al alperujo en conjunto con el bagazo de cebada (BSG), como medios de cultivo sólidos. Finalmente, se analizó la estrategia de acoplar la producción de carotenoides con la recuperación de biofenoles desde el alperujo. Para ello, se utilizó como medio de cultivo, la fracción líquida del alperujo tratado hidrotermalmente (Sevilla, España. Patent No. US 6,849,770 B2 , 2005), para analizar el desarrollo y producción de carotenoides en Rh. mucilaginosa LPSC 638 y dos especies aisladas desde residuos olivícolas (Rh. graminis Y52 y Rh glutinis Y54). Los resultados obtenidos fueron: Capítulo 1. Los EAs y AA ofrecen fuentes de C y N, además de un rango de pH adecuado para el desarrollo de Rh. mucilaginosa LPSC 638. La técnica de desfenolización utilizada redujo el 45% y 30% de biofenoles en EAs y AA, respectivamente. Capítulo 2: La levadura se desarrolló y sintetizó carotenoides en todas las concentraciones de EAs y AA. Metabolizó azúcares presentes y no consumió biofenoles. Los carotenoides sintetizados fueron: toruleno, torularodina, β-caroteno y γ-caroteno. Capítulo 3: La presencia de imidazol no afectó el desarrollo de Rh. mucilaginosa LPSC 638. Se obtuvo la mayor cantidad del caroteno en el medio con mayor concentración de imidazol (1000 ppm). Esta cantidad fue muy inferior respecto a la reportada en bibliografía. Capítulo 4: Rh. mucilaginosa LPSC 638 pudo desarrollarse en medios sólidos, formados por alperujo, BSG y combinación. Los carotenoides sintetizados fueron: toruleno, torularodina y β-caroteno. Capítulo 5: La fitotoxicidad sobre semillas de Lactuca sativa L., se reduce en tratamientos con medios desfenolizados y después del desarrollo de la levadura. No hay efectos fitotóxicos cuando las semillas son tratadas con medios más diluídos (EAs de 5 % y 10%). Capítulo 6: El proceso de desfenolización favorece el desarrollo y síntesis de carotenoides en Rh. mucilaginosa LPSC 638. En el AA tratado hidrotermalmente, Rh. glutinis Y54, Rh. graminis Y52 y Rh. mucilaginosa LPSC 638 producen: torularodina, toruleno, β-caroteno y γ-caroteno. Rh. glutinis Y54 y Rh. graminis Y52, se desarrollaron mejor con respecto a Rh. mucilaginosa LPSC 638. La técnica favorece la recuperación del hidroxitirosol. / The two-phase centrifugation system for extracting olive oil generates a single by- product called alperujo. Due to its physicochemical characteristics, alperujo is a non- ecological waste. The southwest of Buenos Aires province (SOB) constitutes a new area of olive oil production, with a significant intensification of the activity, which drives the need to analyze options for its reuse. This thesis proposes the reconversion of alperujo as a low-cost substrate for producing carotenoid pigments. For this purpose, yeasts of the genus Rhodotorula (Rh. mucilaginosa LPSC 638, Rh. graminis Y52 and Rh. glutinis Y54) were evaluated. First, different alperujo-derived media were prepared and characterized: aqueous extracts (AE) of different concentrations (5, 10, 20 and 30 % w/V) and the liquid fraction of alperujo (AA). On the other hand, the media with the highest concentration of biophenols (EA 30% and AA) were dephenolized using the liquid-liquid partitioning technique. All these media were used to evaluate the development and biosynthesis of carotenoids in Rh. mucilaginosa LPSC 638. The influence of the inhibitor Imidazole on the carotenogenic pathway was also evaluated. Also, yeast metabolism associated with different C and N sources was studied. At the same time, phytotoxicity tests were performed on normal and dephenolized AE and AA on seeds of Lactuca sativa L. Secondly, alperujo was analyzed together with beer spent grain (BSG) as solid culture media. Finally, the strategy of coupling carotenoid production with biophenol recovery from alperujo was analyzed. For this purpose, the liquid fraction of hydrothermally treated alperujo (Sevilla, España. Patent No. US 6,849,770 B2, 2005), was used as a culture medium to analyze the development and production of carotenoids in Rh. mucilaginosa LPSC 638 and two species isolated from olive residues (Rh. graminis Y52 and Rh. glutinis Y54). The results obtained in each chapter were: Chapter 1. EAs and AA provide sources of C and N, as well as a suitable pH for the development of Rh. mucilaginosa LPSC 638. The dephenolization technique used reduced 45% and 30% of biophenols in EAs and AA, respectively. Chapter 2: The yeast developed and synthesized carotenoids at all concentrations of EAs and AA. It metabolized the sugars present and did not consume biophenols. The carotenoids synthesized were: torulene, torularhodin β-carotene and γ-carotene. Lycopene was found only when media contained the inhibitor imidazole. Chapter 3: The presence of imidazole did not affect the development of Rh. mucilaginosa LPSC 638. The highest amount of carotene was obtained in the medium with the highest concentration of imidazole (1000 ppm). This amount was lower than that reported in literature. Chapter 4: Rh. mucilaginosa LPSC638 can grow on solid media, consisting of alperujo, BSG and a combination of both. The carotenoids synthesized were: torulene, torularodine and β-carotene. Chapter 5: Phytotoxicity on Lactuca sativa L. seeds is reduced in treatments with dephenolized media and after yeast development. There are no phytotoxic effects when seeds are treated with more diluted media (5 % and 10 % EAs). Chapter 6: The dephenolization process favors the development and synthesis of carotenoids in Rh. mucilaginosa LPSC 638. In the dephenolized liquid fraction of hydrothermally treated alperujo, Rh. glutinis Y54, Rh. graminis Y52 and Rh. mucilaginosa LPSC 638 produce: torularhodin, torulene, β-carotene and γ-carotene. Rh. glutinis Y54 and Rh. graminis Y52 performed better than Rh. mucilaginosa LPSC 638. The technique facilitates the recovery of Hydroxytyrosol.

To reduce the negative impacts of climate change, electric vehicles (EVs) have emerged as a viable solution in the mobility sector, leading to an increase in battery production and use. For electric vehicle batteries (EVBs) to be sustainable, the total impact of the supply and value chain has to be as low as possible, making the implementation of circular economy (CE) principles a key element in the transition. There is currently limited research regarding circularity implementation in the value chains of EVBs, and especially in developing countries. This thesis explores the key stakeholders in the EVB ecosystem in Nairobi, Kenya, and identifies barriers and enablers for CE implementation. The objective of the thesis is to analyze, based on literature and empirical findings, what activities are deemed necessary to facilitate a circular value chain (CVC) for EVBs in Nairobi. To enable a realistic and thus relatively comprehensive analysis, a case study was conducted involving a literature study, interview study, document review, and workshop. Findings indicate that the Nairobi EVB ecosystem is largely unexplored but that currently, the most important stakeholders can be seen as EV manufacturers and consumers, as well as waste management actors, and second life actors. The key enablers of the ecosystem are government, government agencies, energy providers and suppliers, as well as importers and distributors. The findings indicate the possibility of new essential stakeholders in the future including battery original equipment manufacturers (OEMs), new EV manufacturers and original equipment manufacturers (OEMs), public transport companies, and second life actors. Potential ecosystem enablers include financial actors, research institutions, and insurance companies. Identified barriers and enablers of CE implementation can be divided into five areas, namely technology and infrastructure, supply chain and management, economic, policy and regulation, and social. The findings indicate that barriers identified within the different areas are interconnected, requiring coinciding strategies to be solved and making it difficult to rate them in terms of importance. The findings further suggest that for a CVC for EVBs to be initiated and supported by stakeholders, actors within the ecosystem have to adopt CE strategies to create a closed loop supply and value chain. Battery design needs to enable CE strategies, such as reuse, repair, refurbish, remanufacture, repurpose, and recycle. Furthermore, innovative business models that extend the life cycle of products need to be developed to facilitate the transition to CE. This requires collaboration between the stakeholders in the ecosystem, as well as working with the barriers and enablers identified. To create favorable and enabling system conditions, there is a need for policies and regulations to facilitate the implementation of CE strategies at end-of-life (EoL).

The world is facing a significant depletion of resources. By 2030, our demand will require more than double the resources we are consuming at the moment.  Sustainability is a way of safeguarding that our choices will not negatively impact future generation’s lives due to inadequate resource management. The main problem is that the authorities and the business world do not regard sustainability as a strategic-first business function, rather a collection of disparate solutions. The most crucial question in the discussion about sustainability is how designers, architects, engineers, creators of things, empower the new generations to live in a world of abundance (McDonough & Braungart 2008). It is up to every one of us to build a world that we want to inhabit. Although studies on sustainable innovation practices in large organizations have been located (Bro-Browers, 2010), there is limited academic literature on sustainability in start-ups.  The present thesis aims to show how leadership plays a central role in implementing the sustainability agenda and what traits and styles the CEOs of sustainable start-ups have to possess to drive organizations to success. In this case, success has been defined as the rate of investment attracted by the organization, participation in incubator and accelerator programs, prizes, and all the activities that advance the sustainability agenda.  In order to achieve the research purpose of this study, I conducted a critical literature review of the major leadership theories in the field, coupled with a qualitative research study involving semi-structured interviews administered to ten CEOs of start-ups that develop sustainable services or products. The results were conclusive. CEOs of successful sustainable start-ups displayed the following characteristics: visionary, empowering, tech-savvy, open, acting as coaches and mentors for their organizations, enablers of change, and problem-solvers par excellence. Compared to regular start-ups, the CEOs of sustainable start-ups want to positively impact the world by establishing systems that support the eradication of destructive practices. The business world could use this study’s results as a guide for start-ups and companies that activate in the field of sustainable innovation. Furthermore, it enriches the existing speciality literature since there is little written on leadership in sustainable start-ups.

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