Browsing by Author "Hall, D. H."
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Item Open Access Achieving equilibrium status and sustainable landfill - the holy grail?(The Waste Conference Ltd, 2004-09) Hall, D. H.; Gronow, Jan R.; Smith, Richard; Blakey, N.This paper presents the results of a research contract jointly funded by the Environment Agency and ESART examining the residues of likely post-Landfill Directive waste streams that will need to go to landfill and the time taken to achieve sufficient stabilisation such that management controls can be removed. The first part of the project has identified a number of processes that are likely to be adopted by the waste management industry in order to meet the biodegradable waste diversion targets. Both leachate quality and landfill gas generation data has been assessed for each residue stream. Forward modelling has been undertaken on these data using LandSim2.5 within GoldSim to assess the likely period of management needed in order to achieve equilibrium status.Item Open Access Estimating Pollutant Removal Requirements for Landfills in the UK: I. Benchmark Study and Characteristics of Waste Treatment Technologies(Taylor & Francis, 2006-12-01T00:00:00Z) Hall, D. H.; Drury, D.; Gronow, Jan R.; Rosevear, Alan; Pollard, Simon J. T.; Smith, RichardIntroduction of the EU Landfill Directive is having a significant impact on waste management in the UK and in other member states that have relied on landfilling. This paper considers the length of the aftercare period required by the municipal solid waste streams that the UK will most probably generate following implementation of the Landfill Directive. Data were derived from literature to identify properties of residues from the most likely treatment processes and the probable management times these residues will require within the landfill environment were then modelled. Results suggest that for chloride the relevant water quality standard (250 mg l−1) will be achieved with a management period of 40 years and for lead (0.1 mg l−1), 240 years. This has considerable implications for the sustainability of landfill and suggests that current timescales for aftercare of landfills may be inadequItem Open Access Estimating Pollutant Removal Requirements for Landfills in the UK: II. Model Development(Taylor & Francis, 2006-12-01T00:00:00Z) Hall, D. H.; Drury, D.; Gronow, Jan R.; Rosevear, Alan; Pollard, Simon J. T.; Smith, RichardA modelling methodology using a leachate source term has been produced for estimating the timescales for achieving environmental equilibrium status for landfilled waste. Results are reported as the period of active management required for modelled scenarios of non-flushed and flushed sites for a range of pre-filling treatments. The base scenario against which results were evaluated was raw municipal solid waste (MSW) for which only cadmium failed to reach equilibrium. Flushed raw MSW met our criteria for stabilisation with active leachate management for 40 years, subject to each of the leachate species being present at or below their average UK concentrations. Stable non-reactive wastes, meeting EU waste acceptance criteria, fared badly in the non-flushed scenario, with only two species stabilising after a management period within 1000 years and the majority requiring >2000 years of active leachate management. The flushing scenarios showed only a marginal improvement, with arsenic still persisting beyond 2000 years management even with an additional 500 mm y−1 of infiltration. The stabilisation time for mechanically sorted organic residues (without flushing) was high, and even with flushing, arsenic and chromium appeared to remain a problem. Two mechanical biological treatment (MBT) scenarios were examined, with medium and high intensity composting. Both were subjected to the non-flushing and flushing scenarios. The non-flushing case of both options fell short of the basic requirements of achieving equilibrium within decades. The intense composting option with minimal flushing appeared to create a scenario where equilibrium could be achieved. For incinerator bottom ash (raw and subjected to various treatments), antimony, copper, chloride and sulphate were the main controls on achieving equilibrium, irrespective of treatment type. Flushing at higher flushing rates (500 mm y−1) failed to demonstrate a significant reduction in the management period requiItem Open Access Estimating Pollutant Removal Requirements for Landfills in the UK: III. Policy Analysis and Operational Implications.(Taylor & Francis, 2007-01-01T00:00:00Z) Hall, D. H.; Drury, D.; Gronow, Jan R.; Pollard, Simon J. T.; Smith, RichardThe policy analysis and management implications for achieving landfill equilibrium status within a sustainable timescale (decades rather than centuries) are presented based on modelled results reported previously. Until relatively recently, timescale estimates suggested that equilibrium or landfill completion could be achieved within 40-60 years i.e. the same order of magnitude as financial provision for aftercare. However results of modelling in this study (reported in previous paper) suggest that timescales may be considerably longer (many centuries in some instances) suggesting that financial provision may be inadequate. The role of the most promising and available waste treatment technologies and strategic waste management options in contributing towards achieving equilibrium status are discussed. Results suggest that a re- examination of techniques for accelerating landfill stabilisation, including aerobic and bioreactor landfill, is warranted.Item Open Access Estimating the post-closure management time for landfills containing treated MSW residues.(Eurowaste, 2005-10) Hall, D. H.; Gronow, Jan R.; Smith, Richard; Rosevear, AlanThe Landfill Directive will require the pre-treatment of MSW prior to landfilling. The removal of progressively increasing proportions of the biodegradable fractions from landfilled waste, and the UK Government’s commitment to increase recycling of key waste fractions, will lead to an inevitable change, from the disposal of raw MSW, to the disposal of MSW treatment residues, to landfill. This will undoubtedly change the type and rate of emissions from landfills. The question that this research project has sought to answer is “how long will active management be required for different MSW treatment residues?” The term equilibrium status has been used to define the end point beyond which management of wastes is no longer necessary. Calculating the equilibrium status of waste involves an assessment of the landfill gas emissions, leachate quality and hydraulic status of the landfill. These key parameters change with time as the landfill evolves. Equally, the engineering performance of a site is also changing with the gradual degradation of the liner and capping systems. The question posed above is therefore not easily answered.Item Open Access Recent developments in the application of risk analysis to waste technologies.(Elsevier Science B.V., Amsterdam., 2006-12-01T00:00:00Z) Pollard, Simon J. T.; Smith, Richard; Longhurst, Philip J.; Eduljee, G. H.; Hall, D. H.The European waste sector is undergoing a period of unprecedented change driven by business consolidation, new legislation and heightened public and government scrutiny. One feature is the transition of the sector towards a process industry with increased pre-treatment of wastes prior to the disposal of residues and the co-location of technologies at single sites, often also for resource recovery and residuals management. Waste technologies such as in-vessel composting, the thermal treatment of clinical waste, the stabilisation of hazardous wastes, biomass gasification, sludge combustion and the use of wastes as fuel, present operators and regulators with new challenges as to their safe and environmentally responsible operation. A second feature of recent change is an increased regulatory emphasis on public and ecosystem health and the need for assessments of risk to and from waste installations. Public confidence in waste management, secured in part through enforcement of the planning and permitting regimes and sound operational performance, is central to establishing the infrastructure of new waste technologies. Well-informed risk management plays a critical role. We discuss recent developments in risk analysis within the sector and the future needs of risk analysis that are required to respond to the new waste and resource management agenda.