In order to succeed with the above aim, we have to learn how to handle problems concerning the collection of waste material and to find the most effective treatment process. Urban society requires mainly large-scale solutions for waste water treatment (e.g. activated sludge process) and other organic wastes (e.g. composted or anaerobically digested source-separated household wastes), while rural society has more opportunities to treat its wastes on a smaller scale. It is also important in utilising the treated wastes residues to improve their fertilising and soil structuring effects. Since many organic waste fractions may contain pollutants such as heavy metals, organic chemicals and pathogenic organisms, it is important to develop secure systems for risk assessment and systems for quality control. The effects of residue applications on the long-term sustainment of agriculture as well as on the surrounding environment must also be evaluated.
In 1994, the JLT-Faculty of the Swedish University of Agricultural Sciences (SLU), Uppsala, initiated a research programme on 'Biological Waste in Circulation between Urban and Rural Areas. Biology and Flow of Energy and Material' (Torstensson 1998). The research areas include composting and anaerobic digestion of source-separated household waste, source-separated human urine, safety aspects of the processes and of the end products (compost, digested residues, sewage sludge, human urine) from a health and environmental point of view. The research is of both fundamental and applied character and forms the base for a network in a co-operation with practice and society. Some experiences from this Faculty Theme Research Programme are presented below and a more detailed presentation of some of the projects will be given during the Swedish Workshop at ORBIT99.