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Title: Environmental impacts of and material recovery from biodegradable waste
Author: Gómez, Miguel Gabriel Cebrián
ISNI:       0000 0004 2687 0397
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2009
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The environmental impact of biodegradable waste has resulted in legislative drivers that are designed primarily to reduce the impacts arising from (a) pathogens in the waste, (b) gaseous emissions of carbon dioxide and methane, and (c) the effects of biodegradation in landfill sites on leachates to groundwater. These drivers are considered in this research under three applications: (i) the development of a sustainable technology for the treatment of food wastes to obtain a high quality compost product in a closed-loop situation within a single premises, (ii) the development of a programme to assess the environmental impacts and carbon footprints of food waste treatment options and of other secondary recovery processes, and (iii) the development of a methodology to assess the effects of landfill leachate on groundwaters resulting from deleterious landfill practices and management. Technology to overcome the challenges associated with the conversion of food waste to compost has been developed. The resulting in-vessel composting process produces a high quality compost that meets the highest BSI PAS 100 standard. The key factors in the methodology are the rapid transfer of food waste from the kitchen to composter, the efficient maceration and dewatering of the feedstock, optimisation of the C:N ratio, and the achievement of temperatures high enough to destroy pathogens. The fundamentals of the concept of benchmarking was developed in this work as part of a study to permit the determination of carbon dioxide savings in secondary metal recovery, and extended to carbon footprinting of alternative processes to landfill of food waste to permit a comparison of alternative treatments of food waste. The in-vessel composting methodology described in this work compares favourably with the alternative methods of food waste treatment. A computer software programme, HEDAS, for the statistical analysis of landfill monitoring data to predict borehole behaviour, has been developed. The programme permits assessment of the reliability of the data and ultimately determines the extent of groundwater contamination. In the course of the development of the software, a novel concept was used to determine the best applicable experimental standard deviation (BAESD) to be used to assess the reliability of individual borehole and analyte data. The BAESD is used with the measured standard deviations for individual boreholes and analytes to produce a reliability rating for the individual borehole and analyte. These ratings effectively measure the analytical data against the most stable boreholes at the site and provide viable indicators of step changes in concentration or other anomalies. HEDAS was developed using historical data from the UK Environment Agency’s Thames region, and is now used as their standard for assessing monitored data at landfill sites. The application of HEDAS has now been extended from groundwater and leachate analysis to landfill gas emissions.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral