Das Recycling von edelmetallhaltigen Materialien kann zum Eintrag von Ruthenium in die Kupfergewinnungselektrolyse führen, wo es zu leicht flüchtigem Rutheniumtetroxid oxidiert wird. Um bei der Elektrolyse Rutheniumverluste zu vermeiden, wurde das Oxidationsverhalten von Ruthenium in einer Kupfergewinnungselektrolyse an Bleilegierungs- sowie Diamantanoden mit unterschiedlicher Sauerstoffüberspannung durch Variation der Temperatur sowie der Stromdichte untersucht. Die Ergebnisse der Arbeit zeigen, dass Ruthenium nicht direkt elektrochemisch an der Anode zum Rutheniumtetroxid oxidiert wird. Vor allem an Anoden mit hoher Sauerstoffüberspannung erfolgt parallel zur Sauerstoffentwicklung die Bildung von weiteren Oxidationsmitteln, welche durch chemische Reaktionen mit den im Elektrolyt enthaltenen Rutheniumverbindungen zu leicht flüchtigem Rutheniumtetroxid oxidieren. Diese Reaktionen sind vor allem von der Temperatur und die Bildung der dafür notwendigen Oxidationsmittel vom Anodenpotential abhängig. Zur Vermeidung von Rutheniumverlusten in Kupfergewinnungselektrolysen sollten daher Anoden mit einem niedrigen Potential bei niedrigen Elektrolyttemperaturen eingesetzt werden.

This thesis investigates the impact of yarn and fabric structure on the mechanical recyclability of textile structures. It focuses on variations in yarn twist and form (single or plied) as well as fabric type (woven or knitted) and their respective constructions. The study involved evaluating the mechanical recyclability of 21 cotton textile structures in different constructions, including woven and knitted fabrics, each made using one of the four yarns prepared for this study. The mechanical recyclability was evaluated based on the opening efficiency of the textile structures, together with the average mean fiber length and short fiber content post-tearing. According to the evaluation, a higher fraction of fibers sorted as open and longer fibers resulting from tearing indicated higher recyclability. Based on the evaluation, it was observed that the single yarns tended to be more favorable for mechanical recycling compared to plied yarns. In addition, the effect of the yarn plying twist was multifaceted, with lower yarn twists not necessarily benefiting recyclability. Testing was also conducted to characterize the yarn and fabric structures concerning properties such as count, strength, yarn twist, and thread density of the fabrics. It could be seen that it is of higher relevance to categories of fabric structures based on their density than their fabric type (weaved or knitted) in terms of recyclability. The denser fabric structures' recyclability was more dependent on their fabric construction, whereas, in less dense fabric structures, the yarn structure appeared to have a greater impact. Therefore, determining the interaction of the yarn and fabric structures is important to understand how variations in yarn and fabric structures impact the recyclability of textile structures.

The use of plastic materials has changed the packaging industry, the construction industry, the automotive industry, and many others drastically. Plastics are also abundant in our everyday life. However, its downsides in the society are undeniable and are starting to get attention from law makers, the general public and industries alike. Because of their reliance on fossil feedstock and persistence in nature, efforts are being made to make plastics biobased as well as improving recycling of the material. However, the recycling process is complicated, unoptimized and also differs depending on the product and the country. The differences include the techniques and technology used for sorting, the plastics which are prioritized, and where they end up. This project investigated the recyclability of Renol®, a biopolymer based on lignin, a residual product from the forest industry. To do this, first it was established the most interesting viable thermoplastic resin for the Renol was PP. This was because one of the uses for Renol is in plastic packaging, where PP is one of the most recycled materials. Different compositions of the PP/Renol blend were then produced, containing 5, 10, 20, 30 and 50wt% Renol. Density testing and infrared spectroscopy were then used to determine the highest percentage by weight of Renol that could be included for the material to still be detected as PP in a plastics recycling station. For density, the highest concentration was determined to be 46wt% and 27wt%, for sorting methods using 1.00g/cm3 and 0.95g/cm3 as their thresholds, respectively. Using near-infrared technology and computer algorithms by TOMRA (the European company leading the industry in sorting materials), this value decreased to 20wt%. The quality of recycled polypropylene with Renol (Ren25 and Ren50) and without (rPP) was then measured using the tests stated in the RecyClass protocol for PP containers. It was found that both Ren25 and Ren50 had an elongation at break which was too low compared to rPP. There was a woody smell in the materials Ren25 and Ren50. This was reflected in the measurement for volatiles, where the materials were inserted into a 180°C oven and Ren50 lost the most mass out of the three materials. If the material were to be sent to an official recyclability test, it would most likely fail with the elongation at break, the smell and the volatile substances. In a packaging context it would most likely be sorted and recycled as colored PP at a maximum of 20wt% Renol and for other products with PP, most likely at a maximum of 46wt% Renol. / Användandet av plaster har drastiskt förändrat, bland många andra, förpacknings-, bygg- och bilindustrin. Plaster är också oerhört vanliga i vårt vardagliga liv. Dock är deras negativa egenskaper uppmärksammade av allmänheten, industrier samt lagstiftare. På grund av att traditionellt ha varit beroende av icke-förnybara fossila råmaterial samt dess långsamma nedbrytning i naturen studeras möjligheter till att producera biobaserade plaster samt att förbättra återvinningsprocessen för plaster. I praktiken är återvinningen dock komplex och skiljer sig från land till land och produkt till produkt. Teknologier som fungerar på en typ av plast och produkt fungerar inte nödvändigtvis på en annan. Detta projekt undersökte återvinningsgraden av Renol®, en biopolymer baserad på lignin, en restprodukt från skogsindustrin, och en syntetisk polymer. För detta syfte var det polypropen (PP) som valdes som blandpolymer, då PP är en av de mest återvunna polymererna samt att ett av användningsområden av Renol är förpackningar. Olika blandningar av Renol/PP blandningen producerades, med 5, 10, 20, 30 och 50 viktprocent (wt%) Renol vardera. Tester av de olika blandningars densitet samt analys med hjälp av infraröd spektroskopi användes sedan för att bestämma högsta procenthalten Renol materialet kan innehålla och fortfarande detekteras som PP i en återvinningsstation. Genom densitetsproven fastställdes maxkoncentrationen Renol till 46wt% och 27wt%, för sorteringsmetoder som använder 1.00g/cm3 respektive 0.95g/cm3 som tröskelvärden för PP. Genom infraröd teknologi och datoralgoritmer från TOMRA (europeiska ledare i materialsortering) blev maxvärdet fastställt till 20wt%.  Kvaliteten av återvunnen PP (rPP) jämfördes sedan med den av blandningar av rPP och Renol för att se hur deras egenskaper skiljer sig. Materialtester gjordes med hänvisning till de tester RecyClass-protokollet föreslog för PP-förpackningar. Många tester låg inom toleransen, dock var töjningen vid brott lägre hos Renolblandningen. Renol har också en speciell lukt som inte hittas hos ren rPP samt att den ger av mer volatila ämnen än rPP. Skulle materialet alltså skickas till ett officiellt återvinningstest hos RecyClass, skulle det troligen misslyckas på grund av en lägre töjning vid brott, dess lukt samt dess volatila substanser. Skulle materialet användas i en förpackning skulle den med stor sannolikhet sorteras som färgad PP vid en maxhalt av 20wt% Renol och för andra PP-produkter vid ett max av 46wt% Renol. / El uso de materiales plásticos ha cambiado drásticamente la industria de los envases, la de la construcción, la del automóvil y muchas otras. Los plásticos también abundan en nuestra vida cotidiana. Sin embargo, sus desventajas en la sociedad son innegables y están empezando a llamar la atención de los legisladores, el público en general y las industrias por igual. El proceso de reciclaje de plásticos no es sencillo, ya que requiere limpieza, clasificación y compradores dispuestos. También varía según el producto y el país. En este proyecto se investigó la reciclabilidad del Renol®, un biopolímero a base de lignina, un producto residual de la industria forestal. Para ello, primero se estableció que la resina termoplástica viable más interesante para el Renol era el polypropyleno (PP). Esto se debió a que uno de los usos del Renol es en los envases de plástico, donde el PP es uno de los materiales más reciclados. A continuación, se produjeron diferentes composiciones de la mezcla Renol/PP, que contenían 5, 10, 20, 30 y 50wt% de Renol. A continuación, se utilizaron las pruebas de densidad y la espectroscopia de infrarrojos para determinar el mayor porcentaje en peso de Renol que podía incluirse para que el material siguiera detectándose como PP en una estación de reciclaje de plásticos. En cuanto a la densidad, se determinó que la concentración más alta era del 46wt% y del 27wt%, para los métodos de clasificación que utilizan 1,00g/cm3 y 0,95g/cm3 como umbrales, respectivamente. Utilizando la tecnología de infrarrojo cercano y los algoritmos informáticos de TOMRA (la empresa europea líder en el sector de la clasificación de materiales), este valor se redujo al 20wt%. A continuación, se comparó la calidad del PP reciclado (rPP) con mezclas con rPP y Renol para comprobar que el Renol no empeora la calidad de material reciclado. Los ensayos se decidieron en base al protocol RecyClass para envases de PP. Varias propiedades estuvieron dentro de la tolerancia del protocolo, sin embargo el alargamiento de rotura fue menor en la mezcla Renol. El Renol también tenía un olor particular que no se encuentra en el rPP puro y al final libera más sustancias volátiles que el rPP. Por lo tanto, si el material se enviara a una prueba oficial de reciclaje en RecyClass, probablemente fallaría debido a una menor elongación a la rotura, su olor y sus sustancias volátiles. En caso de que el material se utilice en envases, lo más probable es que se clasifique como PP de color con un contenido máximo de 20wt% de Renol y para otros productos de PP con un máximo de 46wt% de Renol.

No description available.

This research investigates whether the implementation of a curbside recycling system has an effect on the behavior of households with regard to the recycling of packaging material in Sweden. Previous research presented in the literature points out that the decision to engage in recycling behavior, rather than free-riding on the contributions of others, is based on the perceived contribution of others. Complying with social norms and the experience of warm-glow constitute forms of utility that are derived from engaging in recycling behavior. The recyclable packaging materials glass, paper, plastic, and metal, as well as the total of these materials, are considered in this study. Recycling data from 247 municipalities for the years 2010-2020 are used to research this topic. The analysis is carried out using a difference-in-difference model with multiple time periods and a model presented by Callaway and Sant’Anna. A positive and significant change in household recycling was found for plastic packaging waste, amounting to an average increase of 1.57-2.92 kilograms per resident per year when the curbside recycling system was introduced. The change in recycling was also positive for paper, but this result was not robust to changes in the original model specification. Significant increases in recycling were found for total recycling, glass, and metal as well. However, it is considered uncertain whether the identifying assumptions that have to be fulfilled to establish causality of the results are satisfied. The introduction of a curbside recycling system increases household recycling because the time and effort that are required to recycle decrease. The results presented in this study are in line with this notion.

Sequences of matrices arise in many applications in science and engineering. In this thesis we consider matrices that are closely related (or closely related in groups), and we take advantage of the small differences between them to efficiently solve sequences of linear systems and eigenproblems. Recycling techniques, such as recycling preconditioners or subspaces, are popular approaches for reducing computational cost. In this thesis, we introduce two novel approaches for recycling previously computed information for a subsequent system or eigenproblem, and demonstrate good results for sequences arising in several applications. Preconditioners are often essential for fast convergence of iterative methods. However, computing a good preconditioner can be very expensive, and when solving a sequence of linear systems, we want to avoid computing a new preconditioner too often. Instead, we can recycle a previously computed preconditioner, for which we have good convergence behavior of the preconditioned system. We propose an update technique we call the sparse approximate map, or SAM update, that approximately maps one matrix to another matrix in our sequence. SAM updates are very cheap to compute and apply, preserve good convergence properties of a previously computed preconditioner, and help to amortize the cost of that preconditioner over many linear solves. When solving a sequence of eigenproblems, we can reduce the computational cost of constructing the Krylov space starting with a single vector by warm-starting the eigensolver with a subspace instead. We propose an algorithm to warm-start the Krylov-Schur method using a previously computed approximate invariant subspace. We first compute the approximate Krylov decomposition for a matrix with minimal residual, and use this space to warm-start the eigensolver. We account for the residual matrix when expanding, truncating, and deflating the decomposition and show that the norm of the residual monotonically decreases. This method is effective in reducing the total number of matrix-vector products, and computes an approximate invariant subspace that is as accurate as the one computed with standard Krylov-Schur. In applications where the matrix-vector products require an implicit linear solve, we incorporate Krylov subspace recycling. Finally, in many applications, sequences of matrices take the special form of the sum of the identity matrix, a very low-rank matrix, and a small-in-norm matrix. We consider convergence rates for GMRES applied to these matrices by identifying the sources of sensitivity. / Doctor of Philosophy / Problems in science and engineering often require the solution to many linear systems, or a sequence of systems, that model the behavior of physical phenomena. In order to construct highly accurate mathematical models to describe this behavior, the resulting matrices can be very large, and therefore the linear system can be very expensive to solve. To efficiently solve a sequence of large linear systems, we often use iterative methods, which can require preconditioning techniques to achieve fast convergence. The preconditioners themselves can be very expensive to compute. So, we propose a cheap update technique that approximately maps one matrix to another in the sequence for which we already have a good preconditioner. We then combine the preconditioner and the map and use the updated preconditioner for the current system. Sequences of eigenvalue problems also arise in many scientific applications, such as those modeling disk brake squeal in a motor vehicle. To accurately represent this physical system, large eigenvalue problems must be solved. The behavior of certain eigenvalues can reveal instability in the physical system but to identify these eigenvalues, we must solve a sequence of very large eigenproblems. The eigensolvers used to solve eigenproblems generally begin with a single vector, and instead, we propose starting the method with several vectors, or a subspace. This allows us to reduce the total number of iterations required by the eigensolver while still producing an accurate solution. We demonstrate good results for both of these approaches using sequences of linear systems and eigenvalue problems arising in several real-world applications. Finally, in many applications, sequences of matrices take the special form of the sum of the identity matrix, a very low-rank matrix, and a small-in-norm matrix. We examine the convergence behavior of the iterative method GMRES when solving such a sequence of matrices.

During the last two decades, environmental awareness and climate change concerns have encouraged and supported the implementation of recycled techniques in the Transportation Infrastructure Industry for rehabilitating and constructing pavements in the United States. Besides that, pavement roads are public goods that bring economic and social benefits to all countries. Therefore, assessing the pavement structural condition is essential to understand the performance of new materials and determine actions for conservation, maintenance, or rehabilitation. In-situ Pavement monitoring through embedded instrumentation is a type of monitoring technique, which uses several sensors installed within the pavement to obtain the structural responses used in Mechanical-Empirical design to control the performance and define asset management plans. This thesis presents the instrumented response of a Recycled Pavement Section on the Interstate 64 (located in Virginia, USA) to analyze the actual pavement responses (strain and stress) under real traffic and environmental conditions. Several sensors were installed during the construction (including strain gauges, pressure cells, thermocouples, and TDR probes), and two recycling techniques were used (CCPR and Full Depth Reclamation (FDR)) in this project. The Instrumented Recycled Pavement Section analyzed in this research was tested during five months in 2019 to evaluate the effect of temperature, sensor location, and load configuration on the pavement responses collected in the field. During the tests, three loaded trucks ran over the instrumented section. The results showed that the pavement structure is working properly, the stress responses decreased with depth, the maximum strain over the months was compared, and the temperature effect was addressed. Nevertheless, the stress and strain data obtained in each test presented a large variability because it is difficult to control the position where the trucks are passing during this type of experiment. Furthermore, the measured strains were useful to develop a calibrated pavement structural model, which showed that the pavement is expected to have a long structural service life. / M.S. / During the last two decades, different Departments of Transportation have been studying the implementation of recycled materials in pavement structure to provide better economic, environmental, and social benefits by addressing environmental challenges within the Transportation Infrastructure Industry. Among the emerging recycled techniques, Cold-Central Plant Recycling (CCPR) and Full Depth Reclamation (FDR) are included. Both procedures recollect and use the existing asphalt in the rehabilitation or reconstruction of the new pavement structure. The main benefits of pavement recycled materials include reduction of raw materials required and gas emissions. Nevertheless, recycled techniques are not commonly implemented due to the lack of information about long-term performance under real traffic and environmental conditions. In addition, since 2004, when the new Pavement Design Guide was released, the evaluation and validation of new materials require the understanding of the interaction between material properties, traffic, and climate. To address this concern, this thesis analyzed the pavement response measurements obtained in the Interstate 64 Widening Project (Virginia, USA), where two recycling techniques were used (CCPR and FDR). In this project, several sensors were installed during the construction to obtain information regarding the current environment condition (temperature and moisture) and pavement performance (stress and strain). The recycled pavement section was tested during five months of 2019 and trucks with known load configurations were implemented in the field tests. The results showed that the pavement structure is properly working, there is an acceptable stress distribution within the pavement layers, and the overall thickness is expected to have a long structural service life. Besides that, measured strain values obtained through the field experiment were compared with the theoretical ones obtained with computational tools.

The efficacy of five different types of interventions for increasing the number of participants and the quantity of recyclables collected in a corporate-based recycling program were compared. Employees at a corporate research center (N=443) associated with a large state university were asked to bring aluminum cans, glass, and newspaper from home to bins located at work. In addition, in order to track individual employee's recycling behavior, they were asked to write identifying information on each bag of recyclables (i.e., last 4 digits of social security number or a computer identification name). Interventions included appeal messages, two kinds of reciprocity interventions, goals plus feedback, and raffles. A quasi-experimental, modified multiple baseline design was used. More specifically, interventions were given to one building first, and then after a delay, they were administered to the other three buildings simultaneously. Program and intervention information were disseminated by either traditional office memos, electronic mail, or phone mail. Results indicated that only a small percentage of employees participated in the program, and raffles were the only interventions that reliably increased the number of participants and quantity of recyclables. In the hope of being able to predict which employees would participate in the recycling program, prior to the interventions, employees were asked to complete a questionnaire assessing attitudes towards recycling and person variables. More specifically, employees' optimism, environmental concern, beliefs regarding their ability to control environmental outcomes (i.e., “environmental locus of control"), and psychological reactance were assessed. Mean scores on the environmental concern and environmental locus of control scales indicated that employees were quite concerned about the environment and believed that their behavior could have a positive impact on it. Although psychological reactance scores reliably depended on employees’ recycling status (i.e., whether they were non-participants in the recycling program, infrequent participants, or frequent participants), neither it nor any of the other variables could accurately differentiate participants from non-participants in the program. Reasons for the low participation rates and the discrepancy between person variables and participation were discussed, and suggestions for improving future research in this area were made. / Ph. D.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Resource scarcity and increasing environmental pressure have raised the stakes for rethinking material efficiency and textile recycling potential. As current practices fail to feed a closed loop recycling system, this research aims to contribute to the improvement of prevailing practices regarding denim as one of the most popular apparel materials worldwide while focusing on the issue of increasing amounts of discarded post-consumer textiles. The superordinate objective to define the optimum point for denim recycling to retain the value of the cotton fibre as long as possible in a closed loop system, thereby elevating the recycling efficiency, can be considered a key driver for the present research. The following data acquisition is constructed and executed along a mixed method research, in which a qualitative approach based on expert interviews informs and builds up on the quantitative counter part of laboratory use simulation testing on two different denim fabrics and vice versa, leading to an embedded research design. A subjective assessment of potential alterations of the denim fabrics’ visual and tactile characteristics, caused by the use simulation, provides quantitative data through an employed expert panel, which is enhanced by objectively recorded results from the conducted tear strength test and comparative weight investigation to inform changes regarding the physical properties. The applied research methods provide parameters to monitor the decomposition and weakening of the overall fabric structure throughout the experiment. The analysis of the data allowed to assign the number of washing and drying cycles, that a denim garment has undergone, to a corresponding degree of degradation. The presented findings are a valuable resource for developing and innovating current open-end recycling options. The maintenance of the raw material value throughout various reprocessing cycles can counteract the elevated natural fibre scarcity. The insights on the material and process level build a fundament for the successful operationalisation and management of sustainable recycling practices. Further research in this field can pave the way towards value retaining circularity.