Open access publications in the SLU publication database

Abstract

The system for handling and treatment of organic waste is very large and complex, especially in urban areas. It consists of numerous transports, different treatments and different use of residual products. This system also interacts with several other technical systems in society, e. g., district heating, handling of other wastes and material for re-use, and agriculture as a receiver of residues. The complexity of the system under study makes a systematic approach necessary to get the appropriate overview, which has led to the construction of the simulation model ORWARE (Organic Waste Research). This model is intended as a means of analysing the environmental impact, use of resources, and energy turnover of the handling system for organic waste. The model consists of treatment facilities for waste in the system as well as all the transports necessary for collecting the waste and transport residual products to landfills or arable land. ORWARE is modular, all sub-models can be connected to each other. The sub-models developed are: • Sewage plant • Incineration • Landfill • Composting • Anaerobic digestion • Transports • Spreading of residues on arable land ORWARE is used as a scenario tool, the scenarios that are to be studied are constructed by connecting the sub-models needed to represent the scenario and a simulation is performed. An analysis of a region consists of simulation of several scenarios and then evaluation mainly of the differences between the results. The results from the model are: • Air emissions from the entire system • Water emissions from the entire system • Energy turnover for the entire system • Amount of plant nutrients and contaminants recycled to arable land These total emissions can also, in the analysis of the results, be presented as emission/energy turnover/plant nutrient recycled, from every single source. One way of making the results easier to analyse, is to use Life Cycle Assessment methodology to group the emissions into several environmental effect categories, and this is what have been done in the case studies performed. In this report, the modelling of, and indata to, the "compost model", the "transport model" and the "'Transport Distances for Residual Products to Arable land model" are presented. The models are static and the results from a simulation depend only on the flow of material into the models. The model works with a variable vector consisting of 43 elements. In that vector, substances with an environmental effect, substances that affect some process, and substances that are valuable as plant nutrients are included.