Product specific emissions from municipal solid waste landfills

For the inventory analysis of environmental impacts associated with products in Life Cycle Assessment (LCA) there is a great need for estimates of emissions from waste products disposed at municipal solid waste landfills (product specific emissions). Since product specific emissions can not be calculated or measured directly at the landfills, they must be estimated by modeling of landfill processes. This paper presents a landfill model based on a large number of assumptions and approximations concerning landfill properties, waste product properties and characteristics of various kinds of environmental protection systems (e.g. landfill gas combustion units and leachate treatment units). The model is useful for estimation of emissions from waste products disposed in landfills and it has been made operational in the computer tool LCA-LAND presented in a following paper. In the model, waste products are subdivided into five groups of components: general organic matter (e.g. paper), specific organic compounds (e.g. organic solvents), inert components (e.g. PVC), metals (e.g. cadmium), and inorganic non-metals (e.g. chlorine,) which are considered individually. The assumptions and approximations used in the model are to the extent possible scientifically based, but where scientific information has been missing, qualified estimates have been made to fulfill the aim of a complete tool for estimation of emissions. Due to several rough simplifications and missing links in our present understanding of landfills, the uncertainty associated with the model is relatively high.