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.