(137c) Sustainability in the Urban Environment by Thermal Processing of Waste

In the developed world, 75% of the population live in urban areas, a figure projected to rise to nearly 83% by 2030, while in the developing world, this rate of urbanisation is even faster. One of the most important environmental problems associated with urbanisation is the amount of waste that is generated at a rate that outstrips the ability of the natural environment to assimilate it and authorities to manage it. Therefore, if we are to deliver a more sustainable economy, we must do more with less by making better use of resources and putting these materials to good use. The use of municipal solid waste, MSW, to produce energy or fuel is not only an important waste treatment option but it also saves fossil fuels and hence can help meet renewable energy targets, address concerns about global warming and contribute significantly to achieving Kyoto Protocol commitments.

This paper reviews the state of the art technologies used in the thermal treatment processes of waste, which include combustion, gasification and pyrolysis. Within this framework and from a sustainable waste management prospective, a combustion plant was used as an example to investigate the flue gas cleaning systems and in particular the effects of replacing the conventional calcium hydroxide sorbent with sodium bicarbonate in the removal of gaseous acids from the flue gas. This was done to evaluate both the improved efficiency and the economic evaluation of the plant. The work presented in this paper will be further developed to investigate the efficiency of energy recovery and gas cleaning systems using fluidised bed gasification technology.