This project investigated the potential for the regeneration of fibres from cotton-based waste garments. The project focused on the preparation of the cotton waste pulps and assessed the suitability of the prepared material for regeneration of ReCell fibres. Mechanical processes have been developed to degrade the fabrics into a fibrous pulp potentially allowing easier fibre dissolution and purification in the fibre regeneration processes. Wet degradation and dry degradation methods were evaluated and the optimal method identified. It was established that the wet deconstruction method could produce fibres with longer length and lesser degradation of the cellulose than the dry deconstruction method. The pulp produced by wet deconstruction methods could be formed into sheets which were stronger than the pulp produced by the dry deconstruction methods. Although the cotton pulp reclaimed by the wet deconstruction methods requires extra energy to dry, it is still the most attractive processing route since the pulp will be transported to the fibre spinning plant in the form of dry cellulosic sheets. Methods for stripping off the easy care finishes in order to increase dissolution of the cellulosic garments were optimised. The stripping performance was assessed by fibre degradation, contents of the easy care finishes, and solubility of the stripped fibres in selected solvents. It was established that a combination of acidic and alkaline treatment can effect the removal of all easy care finishes and enable efficient dissolution of the pulps for fibre making. ReCell fibres were produced from 100% reclaimed material and a blend of reclaimed cotton pulp and wood pulp and structural and mechanical properties were characterised and compared to the existing Lyocell fibres. It was established that for easy separation of non-cellulosic material from the cellulose-based waste garment pulp the fibres must be modified to avoid formation of tufts. Fibre enrichment by gravity separation was recommended as a pre-requisite process prior to wet cyclone separation and the optimisation of the process was recommended for future work. ReCell processing of dyed waste garments, fibre spinning, fabric construction and wet processing of ReCell fibres have been recommended for future work. The results from this project will be used for pilot tests and later commercial production of ReCell fibres by Lenzing Company. Commercial production of ReCell fibres will contribute to the reduction of economic and environmental challenges caused by textile wastes. Moreover, the findings have identified a potential reduction of pressure on raw material for fibre production by providing an alternative source of material for regeneration of cellulosic fibres.

O presente trabalho busca apreender as representaÃÃes sociais de trabalhadores e trabalhadoras do lixo e suas prÃticas cotidianas, a partir da experiÃncia do Centro ComunitÃrio Santa Terezinha, com o Programa Reciclando - Rede SolidÃria de Coleta Seletiva. Parte-se do pressuposto de que as representaÃÃes sociais se constroem no cotidiano e orientam as aÃÃes das pessoas. Nesse processo de interaÃÃo entre a aÃÃo e as reflexÃes, as representaÃÃes sociais modificam as prÃticas sociais e sÃo modificadas pelas mesmas. Na reflexÃo acerca do trabalho realizado pelos agentes analisa-se a forma de ocupaÃÃo espacial que se deu no morro Santa Terezinha bem como os novos sentidos atribuÃdo Ãs vias pÃblicas como locus de trabalho e nÃo como via de acesso que se dà nos bairros nobres ao redor do Morro. A pesquisa foi realizada com agentes recicladores do referido Centro. Os agentes buscam resignificar seu trabalho atribuindo um conjunto de regras que os diferenciam dos outros profissionais que se ocupam da mesma atividade na Ãrea da pesquisa. Dessa forma estes procuram superar os preconceitos existentes em relaÃÃo à atividade da coleta. Observa-se que a coleta seletiva nÃo se dà em virtude da ausÃncia de um investimento em educaÃÃo ambiental que possibilitaria a separaÃÃo do lixo na prÃpria fonte geradora. Os poucos clientes que separam à resultado da iniciativa pontual dos agentes que negociam em alguns condomÃnios essa separaÃÃo. O cotidiano dos agentes consiste em percorrer as ruas e remexendo o lixo deixado nas calÃadas recolher o material reciclÃvel para posterior venda dos mesmos. Transitar nas ruas competindo com os carros representa um risco para os agentes. Outro risco a que estÃo submetidos à o de adquirir doenÃas em decorrÃncia do contato direto com materiais contaminados. A falta de seguranÃas trabalhistas preocupa os agentes. Acredita-se que se impostos sÃo pagos para assegurar a limpeza urbana esse trabalho deveria ser subsidiado pelo poder pÃblico de forma a garantir uma melhor condiÃÃo de vida e trabalho aos agentes. Os problemas ambientais apontam para a urgÃncia de um desenvolvimento sustentÃvel para a sociedade. EducaÃÃo ambiental e coleta seletiva do lixo sÃo instrumentos fundamentais na luta pela sustentabilidade.

M.Sc., Faculty of Science, University of the Witwatersrand, 2011 / There has been a genuine problem with plastic carrier bags (PCBs) pollution since the 1970’s. A literature review revealed that very few scientific studies have been undertaken globally on PCB. The South African Government promulgated regulations to reduce numbers, encourage reuse and recycling of plastic bags in 2003. The regulations introduced a charge for PCBs. This study looked at the handling and disposal of PCB after 2003 in Gauteng Province, South Africa; and looked at the movement of PCB from major retailers and informal traders to consumers and recycling and recovery. The study excluded the manufacturers and distributors of PCB. It began with the retailers and informal traders being the source of PCB and extended to consumers during their grocery shopping in large retail stores and purchases from informal traders. The study also looked at the individual waste collectors operating in landfill sites, residential and industrial areas to establish the level of recycling of PCB. Buyisa-e-Bag (B-e-B) was at the end of the collection of PCB pathway where it was supposed to provide leadership in the recovery of the bags. Semi-structured interviews were used to collate data on recycling approach with specific focus on PCB and understanding of the legislation. A total of one hundred consumers were interviewed in the shopping malls. Consumers did not know much about the regulations hence they could not explain the reason they have to pay for PCB. Ninety one percent of consumers did not reuse bags for shopping and 68% reused PCB at home to store waste before it is disposed of. Eighty informal traders were interviewed: all indicated that they did not charge for PCB. Forty chain supermarkets managers were interviewed from the shopping centres covered by the study. The retailers were affected by the PCB regulations; they reduced the number of grocery packers and increased security to prevent theft. Nevertheless, they complied with the regulations by selling only the thick bags. Twenty landfill and recycling facilities managers formed part of the study. All landfill managers encouraged general waste recycling to prolong lifespan of the site. Fifty individual recyclers were interviewed in the landfill sites, recycling facilities and on the road side while pushing their trolleys. They found it economically impractical to collect PCBs. Awareness of plastic litter has increased and less is visible though this was not measured. Legal compliance with regulations and specifications needed to be actively driven by all the relevant parties. PCBs are fully recyclable; hence more public awareness is required aimed at preventing the contamination of bags which deters re-claimers from collecting them. B-e-B has not met most of the objectives of their formation and has since been placed under administration by DEAT. Inadequate communication and collective bargaining between the key role parties resulted in the delays in getting the recycling projects off the ground. Major retailers complied with the Government regulations. Informal traders and consumers were generally unaware of regulations and consequences of PCB use. Consumers bought new PCB and in most cases, failed to reuse them for shopping. Recycling of PCBs is not carried out effectively as it is not economically worthwhile. This requires further research to explore the potential uses of PCBs at the end of their lifecycle

This study deals with medium density wood fibre (MDF) and Kraft fibre reinforced polypropylene (PP) composites produced using extrusion followed by injection moulding. Initially, composites were produced with MDF fibre using 10, 20, 30, 40, 50 and 60 wt% fibre, and 1, 2, 3 and 4 wt% maleated polypropylene (MAPP) as a coupling agent. A fibre content of 50 wt% with 3 wt% MAPP was found to be optimum. Alkali treatment of fibre was carried out to improve the interfacial bonding. After treatment, fibre surface charge was found to increase, but single fibre tensile strength (TS) and Young's modulus were (YM) decreased. Alkali treatment reduced composite TS but increased YM. The effects of hemicellulose and residual lignin content were assessed with Kraft fibre (subjected to different stages of a standard Kraft pulping process and therefore consisting of different hemicellulose and residual lignin contents). Fibre surface charge was found to increase with decreasing residual lignin content. Composites containing higher amounts of lignin lead to lower TS and lower thermal stability. Composites were subjected to accelerated weathering for 1000 hours. TS and YM were found to decrease during weathering, and the extent of reduction was found to be higher for composites with higher residual lignin. The reduction of mechanical properties was found to be due to degradation of lignin and PP chain scission as evaluated by increase in PP crystallinity after weathering. As low lignin (bleached) Kraft fibre composites were found to provide superior mechanical properties, as well as more stable during accelerated weathering, further study including optimisation of MAPP content, effects of fibre contents, fibre length, fibre beating, hygrothermal ageing and recycling were carried out with bleached Kraft fibre. MAPP contents of 1, 2, 3, 4, 5, 7 and 10 wt% were used in Kraft fibre reinforced PP composites, and 3-5 wt% was found to be most favourable. Composite fibre content was varied between 30-50 wt%, and 40 wt% found to provide the maximum TS. To investigate the effects of fibre length on composites, fibre fractions of different length distribution were separated using a pressure screen. TS, YM and impact strength were found to decrease and failure strain (FS) increased with decreasing fibre length. To improve the interfacial bonding, the fibre was treated by mechanical beater. Fibre beating increased the TS of composites up to a certain point, beyond which TS decreased. Hygothermal ageing of composites was carried out by immersing specimens in distilled water at 30, 50 and 70 C over an 8-month period. Equilibrium moisture content and diffusion coefficient increased with increased fibre content in composites as well as with increased immersion temperature. Composites without coupling agent showed higher water uptake and diffusion coefficient than that of with coupling agent. After hygrothermal ageing the TS and YM decreased but FS and impact strength were found to increase. An investigation into the effects of recycling was carried out with composites containing either 40 wt% or 50 wt% fibre (bleached Kraft) with 4 wt% MAPP, and recycled up to eight times. For composites with 40 wt% fibre, TS and YM were found to decrease with increased recycling by up to 25% for TS and 17% for YM (after being recycled 8 times). Although TS was lower for virgin composites with 50 wt% fibre than for those with 40 wt% fibre, this initially increased with recycling by up to 14% (after being recycled 2 times), which was considered to be due to improved fibre dispersion, but then decreased with further recycling, and an overall 11% reduction of TS was found after recycling 8 times compared to the virgin composites. YM was higher for virgin composites with 50 wt% fibre than those with for 40 wt% fibre, and also initially increased with recycling but decreased upon further recycling. Recycling was found to increase thermal stability. The TS of composites made by combining recycled with virgin materials was also assessed. Hygrothermal ageing behaviour of recycled composites was also investigated by immersing specimens in distilled water at 50 C over a 9 month period. It was found that the diffusion coefficient and the equilibrium moisture contents of composites decreased with increased number of times the materials were recycled. After hygrothermal ageing, TS and YM of composites were found to decrease. However, the extent of reduction was found to decrease with increased recycling.

The project undertaken was aimed at extending a current craft based jewellery practice. Related by structure and materiality, the research sought to develop exploratory shapes as low seating objects to exist within small scale living spaces and studio apartments. Signaling an increased conscious way of thinking and working, a reflective process examining each form as series, provided an incremental creative strategy. The availability of discarded materials suggested possibilities for a sustainable cost effective option as a mode of contemporary practice. This combined approach was considered impact negative, diffusing global waste, and impact positive providing valid alternatives through functional and aesthetic objects. At present waste materials exist as products are still designed and made on the basis of planned obsolescence, thus an exploitation and escalation of global resources and resultant hazardous outcomes continues. Citing selected writings by Victor Papanek, (1992), and Edwin Datschefski, (2006) provided an understanding of the misuse high impact advanced technologies imposes on the environment. These notions were discussed during the project and in relation to contemporary models of practice which currently use discarded materials to make objects for living. Based on a survey observing the local homewares and furniture industries within Sydney, Australia, and recent published material, a niche market was discovered for challenging conventions of low seating objects. Initial sketches were transformed into marquettes then developed into full size prototypes of multi functional forms. a series of forms were scaled up, made of discarded materials using simple hand crafted processes and minimal production methods. As a reference influences included architects, sculptors and craft practitioners who were examined particularly for their use of discarded materials or for their construction methods. During experimental studies visual source material drew upon an observation and analysis of architecture, skeletal structures and land formations. In an exhibition originally titled, "Be Seated", these forms made as initial prototypes were exhibited at Kudos Gallery, Sydney, Australia, during May 2007. They were later refined and renamed as "Low Life" for a group exhibition "Contained" held at Kudos Gallery during 2008.

The majority of ATM switches that have been proposed only support unicast (point-to-point) connections. Those supporting multicast (point-to-multipoint) connections tend to perform poorly, with acceptable multicast performance only achievable using an excessive amount of hardware. Because of the growing importance of multicast traffic, there is the demand for multicast switch designs which offer both low hardware complexity and high performance. This research investigates a class of multicast ATM switches called recycling switches which can satisfy both requirements. Recycling switch performance is studied using a simulated network model. The major performance parameters measured are the loss rate, mean delay, and delay variance of cells crossing through the switch under uniform and bursty traffic patterns. The reason recycling is not more widely used in multicast switches is the perception that it can lead to some multicast cells receiving lower quality of service than others. This research demonstrates a new priority-based approach to designing recycling multicast ATM switches which addresses this problem while maintaining low complexity and excellent scalability. / Masters Thesis

Doctor of Philosophy (PhD) / Developing an approach that delivers improved environmental performance for metal cycles is the aim of this thesis. Integral to the sustainable use of metals is the need to reduce environmental impacts associated with the mining, refining and recycling activities that supply metal to the economy. Currently, the links between the location and duration of these activities, their resultant impacts and the responsible parties are poorly characterised. Consequently, the changes to technology infrastructure and material flow patterns that are required to achieve sustainable metal cycles remain unclear to both industry and government actors. To address this problem, a holistic two-part methodology is developed. Firstly, a reference schema is developed to address the complexity of structuring analyses of the material chain at different geographical and time scales. The schema identifies actors and system variables at each scale of analysis and guides the level of information detail and performance indicators to be used in material chain characterisation. Material chain characterisation involves modelling material and energy flows for current activities as a series of connected nodes and linking these flows to resultant environmental impacts. The approach identifies the material chain activity responsible for each environmental impact and makes trade-offs between impacts explicit. Sensitivity analysis of the models identifies the key variables that enhance performance. The influence of actors over these variables is assessed to target areas for improvement. This first part of the methodology is illustrated using case studies that assess the current performance of copper material chain configurations at different geographical scales within the reference schema. The analysis of global material and energy flows indicates that the majority of environmental burden in the copper material chain is attributable to primary refining of metal from ore. Modelling of the dominant primary refining technologies using region-specific information for ore grade, technology mix and energy mix reveals that the total environmental impact differs by factors of 2–10 between world regions. The study of refined copper imports to Europe from various regions outside of Europe reveals that lower global warming impacts are achieved at the expense of increased local impacts from the producing regions. Overall, only limited improvements are possible without investing in new technology infrastructure. Evaluation of an innovative copper refining technology finds that collaboration with clean energy suppliers reduces global warming impacts more than changing process design parameters. To better assess the local impacts that are directly controllable by the technology operator, a new indicator incorporating the stability of solid waste is developed. In the second part of the methodology, the link established between actors, their control over key system variables and resultant impacts is used to design preferred future configurations for the material chain. Dynamic models are developed to evaluate transition paths towards preferred futures for individual and collaborative action by industry in the context of externally changing variables (for example, increasing demand for copper and declining available ore grades). Both new copper technology infrastructure and new material flow patterns are assessed in transitions toward preferred futures for a case study of the United States. The improvements resulting from the introduction of new primary refining technology by individual actors are negated by increasing impacts from declining copper ore grades over time. Achieving a combined reduction in local and global environmental impacts requires collaboration between industry actors to immediately increase the recycling of secondary scrap. Significantly, this methodology links actor decisions with their impacts across scales to prompt accountability for current performance and guide useful collaborations between actors. The methodology then delivers a comprehensive assessment of the scale and timing of required interventions to achieve more sustainable metal cycles.

Bibliography : leaves 60-65

Thesis (Ph. D.)--University of Rhode Island, 2005. / Typescript. Includes bibliographical references (leaves 122-126).

A thermal catalytic decomposition process has been developed to recycle used tire rubber. This process enables the recovery of useful products, such as hydrocarbons and carbon blacks. During the catalytic decomposition process, the tire rubber is decomposed into smaller hydrocarbons, which are collected in the process. The solid reaction residue, which normally consists of carbon black, catalysts, other inorganic rubber compound components, and organic carbonaceous deposits, was subjected to a series of treatments with the intention to recover the valuable carbon black and catalyst. The process economics depend strongly on the commercial value of the recovered carbon black and the ability to recover and recycle the catalysts used in the process. Some of the important properties of the recovered carbon black product have been characterized and compared with that of commercial-grade carbon blacks. The composition of the recovered carbon black was analyzed by TGA and EDX, the structure and morphology were studied through transmission electron microscopy (TEM), and the specific surface area was measured by BET nitrogen adsorption. The recovered products possess qualities at least comparable to (or even better than) that of the commercial-grade carbon black N660. Methods for increasing the market value of this recovered carbon black product are discussed. Anhydrous aluminum chloride (AlCl3) was used as the primary catalyst in the process. A catalyst recovery method based on the AlCl3 sublimation and recondensation was studied and found to be non-feasible. It is believed that the catalyst forms an organometallic complex with the decomposed hydrocarbons, such that it becomes chemically bonded to the residue material and hence not removable by evaporation. A scheme for the further study of the catalyst recovery is suggested.