Esta tesis estudia el impacto que tienen los COV presentes en los plásticos reciclados para la economía circular. Actualmente, la industria del reciclaje actual no puede cubrir la creciente demanda de plásticos reciclados de alta calidad en los últimos años. Hasta ahora, el reciclaje mecánico es la solución más utilizada a nivel mundial, y su eficacia y fiabilidad han sido demostradas para el tratamiento del residuo plástico post-industrial. Sin embargo, el mismo reciclaje mecánico aplicado a los residuos plásticos post-consumo da lugar a un material reciclado de menor calidad que solamente es apto para aplicaciones de bajo valor añadido, como son las tuberías de riego o cubos de basura. Por ello, esta tesis evalúa la influencia que tienen las sustancias orgánicas que aparecen en los plásticos reciclados post-consumo dentro el sector del plástico. / Investigación cofinanciada por el Vicerrectorado de Investigación y Transferencia de Conocimiento para el fomento de la I+D+i de la Universidad de Alicante y Cadel Deinking, S.L.

This study focuses on techniques that can be used to fuel next generation reactors. The first two studies are new techniques for recycling used nuclear fuel (UNF) and the third is a method of separating uranium (U) from lithium fluoride (LiF) and thorium fluoride (ThF4) salt also known as FLiTh for a thorium (Th) fuel cycle. The first technique proposed for UNF recycling was to use the cladding as an anode to oxidize the zircaloy and dissolve it into a LiF, sodium fluoride (NaF), zirconium fluoride (ZrF4) salt. Zirconium (Zr) was also reduced and deposited on a tungsten (W) cathode at the same time transporting the Zr through the salt. As commercial zircaloy would be contaminated with UNF oxides, and the oxides will not oxidize as part of the electrochemical process, they would be left at the anode as the Zr is dissolved away. This means the deposited Zr, on the cathode, can be disposed of as low-level waste (LLW) or recycled back into the nuclear industry instead of being stored as high-level waste (HLW). The next technique was fluorination of UNF oxides using ZrF4. Using the same LiF-NaF-ZrF4 salt, uranium oxide (UO2), lanthanum oxide (La2O3), and yttrium oxide (Y2O3) were fluorinated into uranium fluoride (UF4), lanthanum fluoride (LaF3), and yttrium fluoride (YF3). By sampling and recording the change in concentration over time, the reaction rate of all three oxides was determined and a temperature dependent reaction rate was reported from 500°C to 650°C. A zirconium oxide (ZrO2) product layer developed on UO2, but it only slowed down the fluorination process but did not stop it. UO2 and Y2O3 fluorinated entirely but La2O3 did not. The solubility limit of LaF3 in the salt was determined to be the reason the reaction did not go to completion. The last technique was the electrochemical separation of U from FLiTh, to simulate irradiated Th that decays to protactinium (Pa). A constant, albeit small current, was used to deposit U on a W electrode without Th depositing with it. A liquid metal bismuth (Bi) electrode was used as well, and a constant current resulted in Th depositing with the U. To get just U to deposit, the current needed to be applied for a time and then no current applied for a time so the system could reach equilibrium. By cycling these two steps it was possible to get U to deposit in Bi without Th. / Doctor of Philosophy / This study focused on techniques useful to the fabrication of next generation reactor fuels. The first focus was on new techniques for recycling used nuclear fuel (UNF). Nuclear waste currently needs to be stored for hundreds of thousands of years to reach background radiotoxicity levels. If plutonium (Pu) is removed from the waste this time is limited to ten thousand years and if the other transuranics (TRU) are removed the waste only needs to be stored for 300 years to reach background radiotoxicity levels. As recycling UNF can make such a drastic difference, developing techniques for this are of utmost importance. The first technique studied was to show that the zirconium (Zr) in zircaloy cladding could be oxidized and transported through salt. This was done by applying a current between a zircaloy anode and tungsten (W) cathode, dissolving the cladding into the salt. The salt used was lithium fluoride (LiF), sodium fluoride (NaF), and zirconium fluoride (ZrF4) salt called FLiNaZr. This transported Zr through the salt and then deposited it on W. If this process was done with zircaloy contaminated with used nuclear fuel (UNF) oxides, the oxides would not dissolve into the salt as part of the process and would be left behind at the anode as Zr is transported through the salt, effectively separating the two. This alone leads to a 25% reduction in the weight of the UNF that needs to be stored. The next technique studied was converting the UNF oxides into fluorides. This was done by having it react with ZrF4 to make zirconium oxide (ZrO2) and UNF fluorides. The oxides studied here were uranium oxide (UO2), yttrium oxide (Y2O3), and lanthanum oxide (La2O3). UO2 and Y2O3 reacted until no material was left but La2O3 did not. This was due to lanthanum fluoride (LaF3) having a solubility limit in the salt that made it impossible for more to be made and stopping the reacting. The reaction rate for each oxide was found and the order of the reaction rates was Y2O3>UO2>La2O3. This process was a success and should be studied more to ensure it will work with all oxides found in UNF. The last technique studied was electrochemically separating uranium (U) from lithium fluoride and thorium fluoride (ThF4) salt. Thorium (Th) is another nuclear material, and while it cannot fission in a reactor it can be turned into an isotope of U, U-233, that can. To do this Th must be irradiated so it turns into protactinium (Pa) which can then be separated from the salt. In this study U was a surrogate for Pa as it is too radioactive to handle in this lab. First, an inert W electrode was used to deposit U metal, and once it was successful a liquid metal bismuth (Bi) electrode was used. A small constant current was able to deposit U on W without co-deposition of Th. For a Bi electrode, an alternating time of applying current and then letting the system rest was needed to deposit U without co-deposition of Th.

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Recent advances in activated sludge facilities operations utilize sludge recycle flow rate control to minimize adverse effects on the clarifier during peak solids loading situations. Although this control action is directed at the thickening function, there has been speculation that the elevated recycle rates may be responsible for an increased effluent solids concentration. To evaluate the significance of recycle rate to the steady-state effluent suspended solids concentration, identical side-by-side settling columns were operated with recycle rates spanning the range of normal practice. The studies were conducted so that each side-by-side unit received identical activated sludge feed slurries. Replicate experimental units operating at identical recycle rates and receiving identical feed slurries were used to determine experimental error. The experimental design facilitated a statistical determination of the significance of the effect of recycle flow rate. An analysis of variance procedure was pursued, with the conclusion that recycle rate does, in fact, influence suspended solids removal. Ramifications for facilities design and operation is also reviewed.

The ability of spores to germinate, vegetatively multiply and produce new spores and toxin in the larval cadaver is known as recycling. The ability to recycle is an important characteristic since it may enhance effectiveness and persistence of the microbial insecticides in the larval habitat. The ability of Bacillus sphaericus to recycle has only been examined in the low toxicity strain SSII-1 and in the two highly toxic strains 2362 and 1593, both belonging to serotype 5a5ab. This study was expanded and the ability to germinate and recycle of several B. sphaericus strains was investigated. Strains tested represented different serological and DNA homology groups, and expressed either or both toxins (the binary toxin, proteins of 51 and 42 kDa or the 100-kDa toxin). Nontoxic strains were also tested as recombinants expressing the toxin genes or with soluble binary toxin. Results of this study showed that only spores of the highly toxic B. sphaericus strains, which normally produce both, the binary toxin and the 100-Kda toxins, were able to germinate in high percentage and to recycle. The ability of conjugal transfer of plasmids from B. sphaericus to other bacteria was also investigated. The most likely place for conjugation to occur is in the larval cadaver. where spores of B. sphaericus germinate and grow vegetatively and interact with bacteria present in the larval cadaver. Bacillus sphaericus 2362 carrying the broad host range plasmid pAM8&1, was used as donor in filter mating experiments with other B. sphaericus strains, a restrictionless B. subtilis strain and bacteria isolated from field collected larvae. Conjugal transfer of pAMB1 was observed with strains of the same serotype as the donor and two other serotypes. The possibility that the large cryptic plasmid present in B. sphaericus 2362 (180 kb), could promote its own transfer and mobilize the small nonconjugative plasmids pUB110 to other 8B. sphaericus strains was also tested. No transfer was detected. Conjugation experiments in vivo (the larval cadaver) were done by feeding Culex quinquefasciatus larvae the spores of donor 2362 (pAM81) along with spores of the recipient strains, 2362a or 1593-P51. No transconjugants were detected in cadavers 72 hours after feeding the spores. / Ph. D.

Nowadays, Lithium-ion batteries (LIBs) have dominated the power source market in a variety of applications. Lithium cobalt oxide (LiCoO2) is one of the most common cathode materials for LIBs in consumer electronics. The recycling of LIBs is important because cobalt is an expensive element that is dependent on foreign sources for production. Lithium-ion batteries need to be recycled and disposed properly when they reach the end of life (EOL) to avoid negative environmental impact. This project focuses on recycling cathode material (LiCoO2) by direct method. Two automation stages, tape peeling stage and unrolling stage, are designed for disassembling prismatic winding cores. Different sintering conditions (e.g., temperature, sintering atmosphere, the amount of lithium addition) are investigated to recycle EOL cathode materials. The results show that the capacity of the recycled cathode materials increases with increasing temperature. The extra Li addition leads to worse cycling performance. In addition, the sintering atmosphere has little influence on small- scale sintering. Also, most of directly recycled cathode materials have better electrochemical (EC) performance than commercial LiCoO2 (LCO) from Sigma, especially when cycling with 4.45V cutoff voltage. / Master of Science / Nowadays, Lithium-ion batteries (LIBs) have dominated the power source market in a variety of applications. A LIB contains an anode, a cathode and electrolyte. The cathode material is the most valuable component in the LIB. Lithium cobalt oxide (LiCoO2) is one of the most common cathode materials for LIBs in consumer electronics. The recycling of LIBs is important because cobalt is an expensive element that is dependent on foreign sources for production. Lithium-ion batteries need to be recycled and disposed properly when they reach end of life (EOL) to avoid negative environmental impact. The direct recycling is a cost effective and energy conservative method which can be divided into two steps: retrieving the cathode materials from EOL LIBs and regenerating the cathode materials. This project focuses on recycling LiCoO2 by direct method. Two automation modules, tape peeling stage and unrolling stage, are designed for a disassembling line which is the automation line to collect the cathodes materials. The EOL cathode materials is lithium deficient (Li1-xCoO2). To regenerate the EOL cathode materials, lithium is added into structure of cathode materials which is called the re-lithiation process. The different sintering conditions (e.g., temperature, sintering atmosphere, the amount of lithium addition) are investigated for the re-lithiation process. The results show that the capacity of the recycled cathode materials increases with increasing temperature. The extra Li addition in iv Li1-xCoO2 leads to worse cycling performance. In addition, sintering atmosphere has little influence on small- scale sintering. Most of directly recycled cathode materials have better electrochemical (EC) performance than commercial LiCoO2, especially when cycling with 4.45V cutoff voltage.

No / This research aims to conduct an exploratory analysis into current industrial reverse logistics practice in business-to-business (B2B) and business-to-customer relationships (B2C), and determine the financial and operational impact of customer non-compliance in returning distribution equipment back to their source. The analysis was conducted over multiple industry sectors using qualitative research techniques. The research sample included seven industry sectors, providing a response rate of 72 per cent (53 sources approached). The focus was on both B2B and B2C relationships to determine similarities and differences in financial and operational repercussions. The research findings indicate that the efficacy of the reverse logistics system can be undermined by lack of customer compliance, with losses of up to £140 million (B2B). In both B2B and B2C relationships, there is evidence of suppliers suffering financial loss due to customer non-compliance. Due to the small scale of the analysis and the breadth of the industry sectors investigated, these results are not generalisable, but do indicate that this is an area, which could undermine supply chain effectiveness. Practical implications – Non-compliance of this nature carries a direct and highly applicable cost for manufacturers and distributors in the practitioner arena. Suppliers within industry need to acknowledge this issue and manage their reverse logistics more effectively. This paper adopts an innovative focus on an understated feature of the reverse logistics cycle, i.e. the recycling of distribution equipment used to transport outbound and returned products. The paper identifies a range of options, which practitioners can use as guidance when managing the returns system.

Yes / Recycling of polymers is a necessity in our intensively consuming polymer world but the nature of polymers is such that they are prone to thermal degradation when re-extruded and this poses technical challenges to recycling. This article describes research that seeks to rebuild the structure of degraded PA6. We present data from controlled experiments with pristine pPA6 extruded to form a base recycle rPA6 to which we added two chain extenders, separately: one with anhydride multifunctionality (ANHY), highly reactive with amide groups and one with epoxy multifunctionality (EPOX), less reactive. We found from rheological data carried out in the linear viscoelastic region (so as to study structural changes) a striking difference in the ability of the chain extenders to rebuild structure: 306% increase in the complex viscosity of rPA6/ANHY compared to 25% in that of rPA6/EPOX of the base rPA6. Mechanical and thermal (DSC and TGA) tests confirmed the superior efficacy of the multifunctional anhydride chain extender. Beside the practical benefit that ensues from this research, it also provides a strategic platform to develop chain extenders for other degrading polymers on the basis of understanding the degradation chemical reaction and targeting the most reactive end group of the split chains.