Table of Contents

  • In all the Nordic countries waste management strategies focus on waste minimization and on better utilisation of the resources in the waste.

  • A tool for support of decisions at the municipal level has to focus on the most important environmental aspects without losing the national or global perspective. Further the tool needs to be simple in order to secure that the necessary information can be provided locally.

  • The tool for evaluation of environmental impacts of source-sorted municipal organic solid waste management uses a simplified method for life cycle assessment. The Danish EDIP (Environmental design of industrial products) method (Wenzel H. et al,1997) has been used as the base for the environmental assessment calculations. The environmental assessment tool includes a limited number of environmental exchanges (resources and emissions), but the chosen emissions are previously shown to be the most important when evaluating solid waste management systems. The environmental impacts evaluated by this tool are similar to impacts found important in previous Swedish studies (Sundqvist C. et al., 2002a; 2002b) and evaluated by Baky, A. and Eriksson, O. (2003) for the Danish EPA

  • The starting point for evaluation of the waste handling is to define the waste input. Since the tool is intended for assessment of source-sorted organic household waste, only the amount of input waste (ton) as well as the chemical composition for this type of waste is needed.

  • Fuel consumption for waste collection is divided into two parts: the actual collection of waste at each source in an area and the transportation of a full load of waste from the collection area to initial treatment. The waste collection is defined as fuel consumption per ton of waste (MJ/ton) and default values can be given for different types of residential areas and for different type of collection. The values vary much from area to area due to distances and population density, waste collection equipment, waste collection vehicle type and size etc. Thus it may be important that each involved country collects reasonable and well-documented data for fuel consumption for waste collection.

  • The purpose of the pre-treatment stage is to separate missortings, any plastic bags used in collection or other items that can disturb the process or the quality of the residues from the organic material before anaerobic digestion or composting. Some post-treatment after biological treatment may also increase the quality of the residues. The pre-treatment stage comprise of a number of different processes such as

  • The composting module describes the biological degradation of organic matter, air emissions from the process and the amount and composition of the resulting output fractions. Different composting technologies can be modelled. High technology plants will typically use more energy, and have more controlled air emissions (higher removal ratios) than low technology plants.

  • The module for anaerobic digestion describes degradation of organic matter and separation of the waste in gas and in different residual fractions. All kind of anaerobic digestion can be modelled.

  • Some biological treatment plants combine anaerobic digestion with composting, either in the same reactor or as a combination of anaerobic digestion followed by e.g. windrow composting. This module is a combination of the composting module and the biological treatment module. Different technologies combining anaerobic digestion and composting can be modelled. Energy consumption, degradation ratio and control of air emissions depend on the technology level and the physical features of the plant.

  • Nutrients and organic matter are valuable in agriculture and treated organic waste may therefore be applied to agricultural land possibly substituting commercial fertilisers. Apart from the direct substitution effects (saved energy and emissions from production of commercial fertilisers) the application will affect the environmental impacts from the fields after spreading. The nutrients in treated organic waste behave differently than nutrients in commercial fertilisers mainly due to different chemical forms. This affects the nutrient losses from the system, e.g. leakage, surface run-off and emissions to air.

  • Waste incineration has several purposes. First, the aim is to reduce the volume of waste; secondly, energy can be recovered as electricity and/or district heating. However, waste is neither a clean nor homogenous fuel and advanced flue gas cleaning is necessary to meet regulations on emissions.

  • There are two very important aspects in defining the life cycle inventory (LCI) for production of one unit of electricity and district heating. The first aspect is about the technology and energy source and the second on how to allocate resources and emissions from combined power and heating plants. The LCI for energy products is used in calculating the overall resource consumption and emissions whenever electricity and district heating are produced and consumed in the waste management system.

  • Fuel combustion for transport of residues is the main contribution to potential environmental impacts. Thus, production of vehicles is excluded from the study because impacts from this activity are minor compared to emissions during the use stage of the vehicles.

  • I alle de nordiske lande fokuseres der på affaldsstrategier, som går ud på at minimere affaldsmængderne og på at udnytte de ressourcer, der findes i affaldet. Bedre håndtering af byernes affald er ligeledes i fokus, fordi de udgør en central affaldsfraktion med mange uudnyttede potentialer for forbedret håndtering. I de senere år er der etableret mange fuld-skala systemer med kildesortering af det organiske husholdningsaffald og der er gennemført mange projekter for at opnå den bedst mulige håndtering og udnyttelse af affaldets potentialer. Kompostering og bioforgasning er de teknologier, der er brugt for at behandle den organiske del af husholdningsaffaldet; men omfanget af de to metoder og de tekniske systemer, der er anvendt, er meget forskellig i de nordiske lande.