Understanding waste from a climate change perspective: Municipal solid waste management in Canada.

摘要

This thesis analyses the current solid waste management situation in Canada to determine the most effective methods of managing solid waste. To arrive at best practices for sustainable waste management, the relationships between waste composition, diversion efforts, management methods and landfill characteristics were explored for 97 Canadian landfills. Municipal solid waste undergoes biological decomposition to generate landfill gas, a potent greenhouse gas that contributes to global warming. In addition I developed: (1) a statistical analysis of operations and their impact on methane generation, and (2) waste management guidance to reduce emissions from the solid waste sector.Best practices for managing landfills and waste include increased depth, greater compaction, waste diversion and landfill gas capture. These could control pollution and conserve landfill space. Higher disposal fees are significantly statistically related to better waste management practices, such as greater compaction rates (i.e., higher density) and greater depth, as well as more diversion. The average depth of a Canadian landfill is 20 meters with the deepest being 50 meters. If the national average depth was doubled, this action would double the average life of Canadian landfills. The survey showed that the average density of waste is about 750 kg/cubic meter, varying from 125 to 1380 kg/cubic meter. If the national average for waste compaction is increased to 1380 kg/metre, this would have the overall effect of nearly doubling the amount of waste that can be placed into the same landfill space. In addition, higher disposal fees are correlated with lower per capita waste production.Methane recovery is only occurring at 52 landfills but should be carried out at all landfills above a minimum size to reduce greenhouse gases (GHG). Currently, many provinces have targeted landfill gas recovery as part of their greenhouse gas mitigation strategy. Major questions remain with respect to actual methane production in landfill sites. Therefore, to see if operational factors impact emissions production, recovered methane emissions were statistically analyzed. The average absolute error between the statistically modeled and recovered methane from the 29 landfills is 44%. In addition, the linear regression model with an R2 = 0.832, showed that landfill emissions are positively correlated with landfill depth, density and organic waste and negatively correlated with waste diversion.In 2005, only a small portion of the waste stream was recovered or composted. Finally, waste diverted in 2005 from 97 active landfills produced a net decrease of approximately three million tonnes of GHG emissions. Considering all the benefits of waste diversion and its impact on GHG emissions, all municipalities should adopt curbside composting and recycling programs as part of the waste solution to reduce greenhouse gas production and waste generation.Landfill space is in short supply with many landfills reaching their capacity. In order to save landfill space and prevent further harm to the atmosphere, best practices in waste management have to be embraced by landfill sites across Canada. Based on the limited capacity of landfills in many regions of Canada and growing waste generation per capita a shortage of landfill space is expected in the next twenty years, which increases the pressure for sustainable waste management practices.