This thesis investigates the challenges and opportunities for waste management and circular innovation in the context of sustainable development in Zanzibar, with a specific focus on the relevance of youth circular entrepreneurship. Addressing the low integration of stakeholders, inadequate technical support for young innovators, and challenges in leveraging funding, this study aims to provide insights and recommendations to enhance circularity and waste management systems on the islands. Through a comprehensive literature review, qualitative interviews, and analysis of relevant policies and initiatives, the research uncovers the complex dynamics within Zanzibar's waste management value chain. The findings underscore the urgent need for improved stakeholder collaboration, emphasizing the active participation of government agencies, businesses, communities, civil society organizations, and youth entrepreneurs to drive sustainable practices. The study highlights the crucial role of youth circular entrepreneurship in fostering innovation and driving the transition to a circular economy. It identifies the limited technical support, resources, and infrastructure available to young innovators as key barriers, underscoring the necessity of capacity-building programs, mentorship initiatives, and tailored support mechanisms to empower and enable youth entrepreneurs to contribute to waste management and circular innovation. Furthermore, the research reveals the challenges associated with funding and investment for circular initiatives. It emphasizes the significance of climate finance, public-private partnerships, and the mobilization of international funding sources to overcome financial constraints and create an enabling environment for youth circular entrepreneurship. Based on the analysis, this thesis proposes a range of strategies to enhance circularity in Zanzibar, with a particular emphasis on engaging and empowering youth. These strategies encompass stakeholder collaboration, policy development, education and awareness campaigns targeted at youth, technological advancements, and the establishment of financial mechanisms to support youth-led circular innovation. By addressing the identified challenges and capitalizing on the opportunities, Zanzibar can foster a circular economy that not only addresses environmental concerns but also unlocks economic opportunities, resource efficiency, and community well-being. This research contributes to the knowledge base on waste management and circular innovation in Zanzibar, providing a foundation for future research and action toward sustainable development, with a specific focus on youth circular entrepreneurship.

京都大学 / 新制・論文博士 / 博士(工学) / 乙第13545号 / 論工博第4208号 / 新制||工||1984(附属図書館) / (主査)教授 米田 稔, 教授 松井 康人, 准教授 福谷 哲 / 学位規則第4条第2項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Waste recycling is gaining prominence and acceptance compared to landfilling to reduce greenhouse gas emissions. Municipal solid waste (MSW), the largest source of solid waste, is primarily composed of food waste, plastics packaging and papers. Thermochemical recycling technique, such as pyrolysis, is considered as a promising alternative for producing value-added products. Pyrolysis is a process occurring in inert environments at moderate temperatures controlled by parameters such as the reaction temperature, heating rate and residence time to produce bio-oil and biochar. It is also known for its high tolerance for mixed waste stream. In this thesis, fruit waste (FW) consisted of bananas, apples, oranges and cucumbers peels and commercial high density polyethylene (HDPE) as co-pyrolysis feedstock were investigated. Co-pyrolysis experiments were performed in a tubular furnace reactor to investigate the effect of polymer composition, temperature and CO2 atmosphere. HDPE composition was varied between 33–67% to investigate the effect of feedstock composition at 500 ˚C. A composition was fixed and then effect of temperature was assessed in the range 500–700 ˚C. Finally, in CO2 atmosphere, co-pyrolysis experiments were performed with 50% HDPE at 600 ˚C. The collected bio-oil and biochar were thoroughly characterized via different analytical techniques. The effect of different process parameters on bio-oil was studied by gas chromatography-mass spectrometry (GC/MS), proton nuclear magnetic resonance (1H NMR) and Fourier-transform ion cyclotron resonance mass spectroscopy (FT-ICR MS). Biochar samples are analyzed using scanning electron microscopy (SEM), CHNS elemental analysis and Fourier-transform infrared (FTIR). Detailed product composition revealed that formation of hydrocarbons was promoted with increasing HDPE, while significant deoxygenation was observed with increased temperature. In addition, heavier molecules in the bio-oil were studied via FT-ICR MS. HDPE loading and CO2 atmosphere stabilized the biochar by reducing the oxygen content. The results demonstrated the potential use of HDPE as a co-feed with FW in a pyrolysis system to produce valuable products.

Waste management is of growing concern with increasing amount of municipal waste generation and the industry standards are becoming stricter due to climate goals and sustainable development. Waste-to-energy (WTE) systems in the form of waste incineration have been promoted as a low-carbon energy source, but nevertheless have high greenhouse gas (GHG) emissions. Pyrolysis offers an alternative way of utilizing energy which at high temperatures and in the absence of oxygen thermally decomposes material and yields products such as synthetic gas and biochar. Bodø Storstue, a development project for a new sports arena in Northern Norway, has high ambitions for sustainable development. WTE by pyrolysis has been identified as a potential step toward reducing GHG emissions. Thus, this thesis looked into the technical and economic aspects of integrating pyrolysis as a decentralized WTE system. A simulation model was built in Aspen Plus, which shows the energy and mass balance through the different modules in the system. An economic analysis was performed using MS Excel which included the levelized cost of electricity and net present value calculation. The results suggest that the electricity demand in Bodø Storstue can be met by using pyrolysis for power generation, and that carbon can be stored in biochar which reduces the emissions compared to traditional waste incineration. Future studies should include a simulation model based on tested feedstock composition which would make the simulation more representative of true conditions. The price of biochar should also be included in the economic analysis to obtain more precise conclusions about the economic conditions that impact investment decisions. / Avfallshanteringen skapar en växande oro världen över med ökande avfallsmängder och strängare bestämmelser för industrianpassning till nya klimatmål och nya strategier för hållbar utveckling. Energiutvinningssystem ur avfall i form av direkt avfallsförbränning, s.k. waste-to-energy (WTE), har marknadsförts som en miljövänlig energikälla men låga utsläpp, men har trots detta en viss del fossilbaserad kolinnehåll samt höga helhetsutsläpp av växthusgaser. Pyrolysprocesser erbjuder ett alternativt sätt att utnyttja energi genom att termiskt bryta kolväten vid höga temperaturer och i frånvaro av syre ner till enklare molekyler och således generera gasformiga produkter samt biokol. Bodø Storstue är ett utvecklingsprojekt för att bygga en ny multifunktionell idrottsarena i norra Norge, med höga ambitioner för integrerat miljötänkande. WTE genom pyrolys har identifierats som en lovande åtgärd för att minska växthusgasutsläppen från arenan. Målet härmed är således att undersöka de tekniska och ekonomiska förutsättningarna for att integrera en nyutvecklad pyrolysprocess för arenan i form av ett decentraliserat kraftvärmeverk med lokal avfallshantering där också en del biokol utvinns i fast form för att potentiellt lagras som ren kol eller för att användas till jordförbättring. Simuleringsmodeller för kraftvärmesystemet byggdes i AspenPlusTM baserade på avfallspyrolys och syntesgasförbränning, som beräknar energi- och massbalanser genom olika delmoduler. I ett nästa skede utfördes förenklade ekonomiska analyser med andra verktyg för att sammanfatta elkostnader och nettonuvärdeuträkning. Resultaten tyder på att elbehovet i Bodø Storstue kan tillgodoses genom att använda avfallspyrolys för kraft- och värmegenerering, och att kol kan lagras i form av biokol vilket minskar utsläppen jämfört med traditionell avfallsförbränning. Framtida studier bör inkludera en simuleringsmodell baserad på testad och verklighetstrogen avfallssammansättning, vilket skulle göra simuleringen mer representativ för verkliga förhållanden på arenan. Värdet på biokol bör också inkluderas i den ekonomiska analysen för att få mer precisa slutsatser om de ekonomiska förutsättningarna.

I Sverige sker i dagsläget ingen återvinning av färg. Istället bränns omhändertaget färgavfall medan återstående slaggprodukter läggs på deponi. Däremot förekommer återvinning av färg i bland annat USA. Med denna bakgrund har syftet med denna studie varit att undersöka om det med hänsyn till produktsäkerhet och kvalité är tekniskt möjligt att återvinna färg samt undersöka hur återvinning av färg skulle påverka miljön. Återvinning av färg har gjorts på försök genom att ta 1 dl färg från totalt 127 färgburkar som annars skulle blivit avfall. Den återvunna färgens fysikaliska egenskaper och sammansättning har undersökts med avseende på densitet, torrsubstanshalt, glödförlust, askhalt och metallhalt. Av intresse ur produktsäkerhetssynpunkt är att endast mycket låga metallhalter uppmättes vilket indikerar att produktsäkerhet inte är ett hinder för färgåtervinning. Utöver fysikaliska egenskaper och sammansättning har även den återvunna färgens kvalité undersökts. Utifrån de lärdomar som kan dras från detta projekt görs sammantaget bedömningen att det är fullt möjligt få en färg med godtagbar kvalité genom återvinning av färg. Oberoende av dessa huvudsakligen praktiska tester har miljöpåverkan av färgåtervinning undersökts genom att undersöka hur tillverkning av ny färg påverkar miljön. Av den totala miljöpåverkan vid tillverkning av färg sker 84-96 % vid utvinning av råmaterial vilket är en stark indikation att återvinning av färg har en potential att bidra till en bättre miljö. / In Sweden, no recycling of paint currently takes place. Instead paint waste is incinerated while the remaining ashes are put in a landfill. However, recycling of paint already exists in the United States. With this background, the aim of this study has been to examine if it technically possible to recycle paint, in regards to products safety and quality, and to examine how recycling of paint would affect the environment. As part of this study paint has been recycled by taking 1 dl of paint from a total of 127 paint cans out of the waste stream at a local recycling station. The physical characteristics and composition of the recycled paint has been examined (density, dry matter content, loss on ignition, ash content and metal content). Of interest in regards to product safety is that the recycled paint contained only relatively low concentrations of metals. This indicates that product safety is not an obstacle for paint recycling. In addition to physical characteristics and composition, the qualities of the recycled paint have been evaluated. Based on the lessons learned in this project the overall conclusion is that it would be fully possible to obtain paint of acceptable quality through recycling. Moreover a study has been made on how recycling of paint would affect the environment by studying the environmental impacts of paint manufacturing. An important finding is that the extraction of raw materials accounts for 84-96 % of the total environmental impact of paint manufacturing. This is a strong indication that paint recycling has a potential to benefit the environment.

Sophantering är av avgörande betydelse för folkhälsan i utvecklingsländer. I Uganda är ett av huvudproblemen för folkets hälsa den bristfälliga sophanteringen. För att fastställa problemet har vi genomfört en fallstudie under 10 veckor genom att studera hur sophanteringen fungerar i staden Mbale (Uganda) samt vilka konsekvenser denna får för befolkningens hälsa. Intervjuer, observationer och dokument har använts för att få en detaljerad beskrivning av fenomenet. Studien ger en bakgrund till vikten av en adekvat sophantering för folkets hälsa samt en introduktion till landet Uganda. I resultatet ges en utförlig beskrivning av hur sophanteringen ser ut i Industrial division, Mbale och vilka problem som påverkar den. I diskussionen redogörs för underliggande problem utifrån A. Sens teori Utveckling som frihet. B. Murphy’s modell The fourth dimension of health promotion används för att utvärdera det hälsoarbete som görs samt ge förslag till förbättring. Problemen kan sammanfattas genom att poängtera vikten av att samhället tar sitt ansvar för befolkningen bl.a. genom prioritering av infrastrukturen. Långsiktiga och hållbara lösningar bottnar i bekämpandet av korruption och fattigdom. Det förebyggande hälsoarbetet behöver förändras till att bli mer empowerment baserat. / Waste management is of crucial concern for public health in developing countries. In Uganda one of the main problems connected to public health is a poor waste management system. To define the problem of waste management and to investigate its consequences for people’s health we made a case study during ten weeks in Mbale, Uganda. Interviews, observations and documents have been studied. Uganda as a country is introduced in the background and the importance of waste management for the public’s health is explained. An extensive description of how waste management works in Industrial division, Mbale and the problems affecting it is given in the results. In the discussion the underlying problems are described with the help of A Sen’s theory Development as freedom. B. Murpy’s model The fourth dimension of health promotion is used to evaluate the health promotion work that exists and to give suggestions of improvements. The problems can be summarised with the importance for the society to take responsibility for the population e.g. by prioritising the infrastructure. Sustainable and long-term solutions are grounded in combating corruption and poverty. A change in the health promotion work needs to be done and based upon empowerment.

Thailand is called the kitchen of the world; the country produces food and beverage products and exports around the globe. According to previous studies, there is not enough data on food waste in Thailand and worldwide. This study aims to analyse the characteristic of the loop of learning in assisting the process of organizational change and explain how it can support sustainable change in Food Waste Management. Even though a loop of learning is used frequently to develop changes in organizations, the relationship between organisational learning methods and organisational change is still not yet identified.  The qualitative method, particularly a case study, was used to accomplish the aim. The case study focuses on how production companies develop their organisational change toward sustainable Food Waste Management in Thailand by aligning the management's thinking level with a loop of learning. The data collection method is a semi-structured interview with 12 managers of different food and beverage manufacturing companies. The results show that current actions are 1) following the existing regulation and finding solutions for challenges, 2) developing better methods and re-using waste, and 3) setting new strategies to achieve sustainable Food Waste Management. Thus, those actions have the quality of single, double and triple-loop learning.  Furthermore, the research findings indicate that changing norms with environmental concerns can influence other factors, such as laws and stakeholder expectations. The organizational change process must involve continually thinking in the loop of learning from an individual and organisational perspective. These authors conclude that the nature of loop learning is a process that individuals and organizations can use to identify and reclaim problems; this process assists organization to realise the need for changes and continue developing solutions for those matters. The outcomes of continuous thinking will present changes in action which reach organisational change.

Textile waste amounts and its utilization are pressing problems in the EU today, with further expected worsening as legislations come into play, increasing collection rates. The EU strives towards a more sustainable future, however this future might entail initial disimprovement, as consumption and disposal behaviour are further expected to increase. The study showed by mapping the future material flow that potential scenarios are severe, in waste volumes and it is unclear how they will be handled and utilized. It is of highest importance to prepare to mitigate them through levers that enable preferred circular flows towards a more sustainable future. Reusing clothing might be such a lever that promises to partially substitute the demand for new products. Through quantitative research and a systemic and dynamic analysis, this study concludes that waste management remains an even more acute problem, whilst slowing consumption through reuse and maintenance of existing products might be a (small) step in the right direction.

Small-scale anaerobic digesters, known as biogas plants, were applied as an optimal livestock waste treatment as well as biogas supply for cooking and lighting demand for small-scale farmers in Vietnam. Although the biogas technology was introduced for nearly 30 years, the number of the constructed biogas plants is still limited. The current development of biogas plants is far below the real demand on livestock waste treatment that has increased significantly. This paper gives a comprehensive overview on the biogas plant development in Vietnam and attempts to address the challenges and discuss appropriate solutions for the further biogas development. / Mô hình lên men yếm khí quy mô nhỏ (được biết với tên hầm ủ khí sinh học) đã được ứng dụng hiệu quả trong xử lý chất thải chăn nuôi cũng như cung cấp nguồn nhiên liệu phục vụ nhu cầu nấu ăn và thắp sáng cho các hộ chăn nuôi nhỏ ở Việt Nam. Mặc dù đã hiện diện gần 30 năm, nhưng số lượng hầm ủ khí sinh học vẫn còn hạn chế. Sự gia tăng số lượng hầm ủ khí sinh học chưa theo kịp với nhu cầu về xử lý chất thải chăn nuôi đang ngày càng gia tăng. Bài báo trình bày các chặng đường phát triển của hầm ủ khí sinh học tại Việt Nam, ghi nhận các thách thức trong việc nhân rộng hầm ủ khí sinh học trong thực tế và thảo luận một số giải pháp để phát triển công nghệ khí sinh học.

Municipal solid waste (MSW) in Vietnam has been increasing quickly and became one of the most considered environmental problems in Mekong Delta (MD) region covering 13 provinces and municipalities in the south of Vietnam. With a considerably large amount of MSW, the region produces about 5% of the total amount of MSW of the country. The collection rate of solid waste is about quite high (65 - 72%) in the cities and rather low (about 40 - 55%) in the rural areas, with a high content in organic matter (about 60 - 85%). The climate of MD can be characterized as tropical and monsoonal with a high rate of humidity and a strong impact of flooding. Like other regions too, the MSW collection and treatment system is still underdeveloped and rudimentary, with disposal sites being the sole dumping method of the unsorted MSW remaining untreated by any mechanical and biological pre-treatment steps. Within this paper, the current treatment, management and operation of MSW systems are introduced, as well as the identification of advantages and disadvantages, environmental impacts, potential risks of the MSW system within the impact of global climate change. The situation of MSW treatment and management is correlated with the climate change impact and the integrated solid waste management is introduced as a new approach for adapting the environmental protection awareness by considering the climate change for the longterm sustainable development orientation. / Sự gia tăng chất thải rắn ở các đô thị Việt Nam ngày càng nhanh và chất thải rắn đang là một trong những vấn đề môi trường được quan tâm hàng đầu. Đồng bằng Sông Cửu Long (ĐBSCL) nơi có đến 13 tỉnh và thành phố nằm ở phía Nam Việt Nam. Với lượng chất thải không nhỏ, chiếm khoảng 5 % tổng lượng chất thải rắn sinh hoạt của quốc gia. Tỷ lệ thu gom chất thải rắn thấp, chiếm khoảng 65 - 72 % ở thành thị, tỷ lệ này ở nông thôn thấp 40 - 55%, chất thải có hàm lượng hữu cơ cao chiếm khoảng 60 - 85%. Khí hậu nhiệt đới gió mùa với độ ẩm không khí cao và chịu ảnh hưởng lớn của lũ lụt hàng năm. Cũng như các khu vực khác, hệ thống thu gom và xử lý rác thải ở khu vực ĐBSCL còn rất thô sơ và lạc hậu, bãi rác là nơi duy nhất tiếp nhận trực tiếp hổnhợp rác thải không phân loại và qua bất kỳ công đoạn tiền xử lý nào. Trong phạm vi bài viết này, chúng tôi giới thiệu hoạt động vận hành hệ thống quản lý và xử lý rác đô thị trong khu vực đồng thời phân tích các thuận lợi và bất lợi, cũng như các tác động môi trường, những rủi ro tiềm ẩn trong điều kiện ảnh hưởng của biến đổi khí hậu toàn cầu - khu vực ĐBSCL là nơi chịu ảnh hưởng nặng nề nhất. Tình hình quản lý và xử lý rác được cân nhắc trong điều kiện tác động của biến đổi khí hậu, đồng thời quản lý tổng hợp rác thải cũng được đề xuất như một các tiếp cận mới nhằm đáp ứng nhiệm vụ bảo vệ môi trường trong điều kiện biến đổi khí hậu theo định hướng phát triển bền vững lâu dài.