Assessing current practices and alternative scenarios for the management of public waste in the city of Vienna

This study examines public waste, meaning solid waste generated "on the go" in public spaces such as streets, parks and plazas. Despite containing a high proportion of recyclable materials, this waste stream is frequently overlooked in both academic research and circular waste management strategies. Using Vienna, Austria, as a case study, the research employs Material Flow Analysis (MFA) to systematically assess public waste flows and evaluate five alternative management scenarios. The scenarios include strategies such as enhanced source separation and advanced automated sorting of residual waste, aiming to enhance circular material use in public space. Waste flows were analyzed in detail across 16 sub-fractions, enabling a highly granular and accurate modelling approach. Although public waste represents only 4.5% of municipal solid household waste in Vienna, it contains a high proportion of recyclable materials (65%), much of which is currently not recovered due to a lack of waste separation (in the status quo less than 3% of recyclables are source-separated). Study results show that scenarios involving advanced residual waste sorting achieve the highest overall material recovery, where over 40% of publicly disposed waste is recovered for recycling. However, if additional factors like the quality of recovered materials are taken into account, the performance difference between separate collection and automated residual waste sorting is expected to diminish. This study provides the first detailed modelling of public waste flows and a robust foundation for evidence-based decision-making and future research on economic and environmental impacts.