EASEWASTE—life cycle modeling capabilities for waste management technologies

Abstract

The management of municipal solid waste and the associated environmental impacts are subject of growing attention in industrialized countries. European Union has recently strongly emphasized the role of LCA in its waste and resource strategies. The development of sustainable solid waste management systems applying a life cycle perspective requires readily understandable tools for modeling the life cycle impacts of waste management systems. The aim of the paper is to demonstrate the structure, functionalities, and LCA modeling capabilities of the PC-based life cycle-oriented waste management model EASEWASTE, developed at the Technical University of Denmark specifically to meet the needs of the waste system developer with the objective to evaluate the environmental performance of the various elements of existing or proposed solid waste management systems. The EASEWASTE model supports a full life cycle assessment of any user-defined residential, bulky, or garden waste management system. The model focuses on the major components of the waste and reviews each component in terms of the available waste management options, including biogasification and composting, thermal treatment, use on land, material sorting and recycling, bottom and fly ash handling, material and energy utilization, and landfilling. In order to allow the use of the model in an early stage where local data may be limited, default data sets are provided for waste composition and quantities as well as for the waste technologies mentioned above. The model calculates environmental impacts and resource consumptions and allows the user to trace all impacts to their source in a waste treatment processes or in a specific waste material fraction. In addition to the traditional impact indicators, EASEWASTE incorporates impact categories on stored ecotoxicity, specifically developed for representation of the long-term impacts of persistent pollutants in landfilled waste. The model reports data at any stage of the LCA and supports identification of most sensitive parameters as well as overall sensitivity analysis and material balances for all substances passing through the system. The structure of the model is presented, and its functionalities are demonstrated on a hypothetical case study based on waste data from a large Danish municipality. The aim of the case is to demonstrate new waste treatment technologies and their modeling capabilities as well as the LCA modeling capabilities in EASEWASTE to identify the most important impact categories and the main sources of contributions to these in the system for treating the waste. Based on the results, the modeling features, user flexibility, and transparency of the EASEWASTE model are discussed. EASEWASTE is demonstrated to be a versatile and detailed (engineering) model with a strong differentiation of individual fractions, but it requires an engineering background to use all the features. The model is especially developed for the modeling of the handling of municipal solid wastes, and therefore, it does not support other wastes such as demolition and large commercial waste. The model is useful for an iterative approach to waste system modeling; its database access supports a quick primary calculation of the impacts from a designed waste system using default data, and based on this, a gradually refined focusing on the parts which contribute the most to the total impacts. The EASEWASTE model allows the user to supply detailed data for waste generation, waste composition including material fractions and chemical properties, sorting efficiencies, waste collection, and waste treatment technologies. More generic LCA modeling tools developed for LCA of products do not support these steps of the modeling to the same extent, and also the creation and evaluation of waste collection, waste transportation, and waste treatment technology individually or in a designed scenario is much easier in EASEWASTE. EASEWASTE has been used in the modeling of a number of real case studies, and much data have been incorporated into it. Several research projects are currently underway under the Danish 3R (Residual Resources Recovery) research school in support of its further development. There are, however, still many issues that have to be improved significantly to facilitate application by other users than model developers. The improvements in consideration are to provide data for more treatment and disposal technologies and more flexibility. The current version of the model supports the environmental assessment (environmental impacts and resource consumption) of household and small commercial business units waste treatment systems in a Danish context, but it is the ambition that future versions of the model shall support the inclusion of other waste types as well as economic evaluation and that the geographical coverage shall be extended to other countries.