Abstract:
The UK is reliant on landfill as a waste management option with some 72% w/w of
municipal waste landfilled in 2003/04. This thesis advances an argument that landfill, as
practised historically and currently, is unsustainable. This thesis demonstrates,
specifically, that current legislative aftercare provisions of 30-60 years are inadequate
with reference to modelled landfill completion times (the achievement of equilibrium
status) of up to 2,000 years. Uniquely, the research quantifies the scale and significance
of methane emissions during the early stages (up to 28 months waste age) of landfill
operations at 21 UK landfills using a modified flux box. The onset of methanogenesis is
quantified for the first time, using a series of in situ monitoring probes installed at one
UK landfill site.
A significant and novel finding is that the advective flow of landfill gas is preferentially
dominated by lateral movement, evidenced here by examination of a predominantly
municipal solid waste (MSW) landfill site in Southern England. The direct implications
of this finding for the design of landfill gas management systems are discussed.
For future landfills, this research has examined a number of UK scenarios in which the
gas and leachate characteristics from waste residues going to landfill are modelled to the
point of completion or achievement of equilibrium status. This analysis now allows for
a comparative assessment of the future performance of landfills. Under these scenarios,
completion times can be reduced in some instances {e.g. landfilling of compost and
mechanical biological treatment residues) and extended in others (incinerator bottom
ash). Problematic contaminants remain; notably arsenic, chromium and lead.
Using the research herein, the work describes the application of a landfill gas
management hierarchy. In part response to the requirements of the EU Landfill
Directive, this provides a science-based framework for operators to maximise protection
of the environment and human health from gaseous emissions. The research provides
evidence that can be used by landfill managers seeking to maximise landfill collection
efficiency. This contributes to regulators managing public and environmental health and
is increasingly significant for climate change.