Environmental Systems Analysis of Waste Management, with Emphasis on Substance Flows and Environmental Impact

This thesis is about environmental systems analysis and computer modeling in waste management planning. Focus is on substance flows throughout and environmental impact caused by municipal waste management systems. Because municipal waste management systems are complex, structured frameworks are needed in planning to analyze and evaluate possible system designs. Computer models are well suited for this task. Such models have been developed since the 1960's, several of which address environmental issues. A specific approach is employed in the ORWARE model (ORganic WAste REsearch), which calculates substance flows and potential environmental impact, based on a life cycle perspective. ORWARE is being developed in cooperation between several Swedish research institutes and institutions: the Royal Institute of Technology (KTH), the Swedish Environmental Research Institute (IVL), the Swedish University of Agricultural Sciences (SLU) and the Swedish Institute of Agricultural Engineering (JTI). ORWARE consists of several sub-models for transporting, treating and disposing waste. The sub-models of incineration and landfilling, which previously handled only biodegradable waste, have been further developed to include parameters of non-biodegradable waste. Case studies were performed in the municipalities of Stockholm and Uppsala, where ORWARE was used to evaluate the substance flows and potential environmental impact of planned or possible solutions to waste management. The case studies represent the ORWARE model as structured before and after non-biodegradable waste fractions were included. There is an apparent influence of case-specific circumstances, so that results cannot be directly transferred from one region to another. Despite this, the case studies were rather consistent in showing that biological treatment of biodegradable waste will not, as suspected by many, cause negative net environmental impact for those impacts evaluated. Metal contamination of organic residues used as fertilizer is however an important limitation to the environmental feasibility of biological treatment systems. Increased recycling of recyclables was positive in Uppsala, provided recycled materials cause equal or less environmental impact than virgin materials in product manufacturing. The positive effects of increased source separation are often part of the enlarged system analyzed with ORWARE. In direct connection to waste management, there is on the other hand often rather an increase in environmental impact, caused by e.g. increased transportation. In a more limited analysis, the net benefits would thus easily be overlooked.

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