Thesis (M.S.)--University of Missouri--Rolla, 1996. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed November 24, 2008) Includes bibliographical references (p. 117-118).

Thesis (M. Sc.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 92-101).

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

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

Global energy demands combined with environmental restrictions are fueling a move to alternative energy sources. Biofuels are formed from biomass; the MixAlco process is one such method. In this work, food scraps are explored as a potential feedstock to the MixAlco process. Batch fermentation with various temperatures, buffers, and pH control methods elucidated the behavior of food scraps during fermentation. The pH and reactor configuration were limiting factors when maximizing production. A fermentor was developed and tested with constant pH control. This resulted in elevated concentration (100 g/L) and selectivity (82%) of desired products. The fermentation resulted in elevated concentrations, but low conversion of solids. The undigested material may serve as a nutrient source for fermenting lignocellulosic feedstocks. Combining various nutrient sources with lignocellulose, such as bagasse, resulted in additional production and further conversion. Multiple nutrient sources were tested resulting in total acid concentration ranging from 20.2 to 34.5 g/L.

Global energy demands combined with environmental restrictions are fueling a move to alternative energy sources. Biofuels are formed from biomass; the MixAlco process is one such method. In this work, food scraps are explored as a potential feedstock to the MixAlco process. Batch fermentation with various temperatures, buffers, and pH control methods elucidated the behavior of food scraps during fermentation. The pH and reactor configuration were limiting factors when maximizing production. A fermentor was developed and tested with constant pH control. This resulted in elevated concentration (100 g/L) and selectivity (82%) of desired products. The fermentation resulted in elevated concentrations, but low conversion of solids. The undigested material may serve as a nutrient source for fermenting lignocellulosic feedstocks. Combining various nutrient sources with lignocellulose, such as bagasse, resulted in additional production and further conversion. Multiple nutrient sources were tested resulting in total acid concentration ranging from 20.2 to 34.5 g/L.

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

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Made available in DSpace on 2014-10-09T12:40:52Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:28Z (GMT). No. of bitstreams: 1 02950.pdf: 4952382 bytes, checksum: 1dddfe6ca71077632e2bdf2d56006ba7 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP