Comparing urban solid waste recycling from the viewpoint of urban metabolism based on physical input–output model: A case of Suzhou in China

Highlights: ► Impacts of solid waste recycling on Suzhou's urban metabolism in 2015 are analyzed. ► Sludge recycling for biogas is regarded as an accepted method. ► Technical levels of reusing scrap tires and food wastes should be improved. ► Other fly ash utilization methods should be exploited. ► Secondary wastes from reusing food wastes and sludge should be concerned. - Abstract: Investigating impacts of urban solid waste recycling on urban metabolism contributes to sustainable urban solid waste management and urban sustainability. Using a physical input–output model and scenario analysis, urban metabolism of Suzhou in 2015 is predicted and impacts of four categories of solid waste recycling on urban metabolism are illustrated: scrap tire recycling, food waste recycling, fly ash recycling and sludge recycling. Sludge recycling has positive effects on reducing all material flows. Thus, sludge recycling for biogas is regarded as an accepted method. Moreover, technical levels of scrap tire recycling and food waste recycling should be improved to produce positive effects on reducing more material flows. Fly ash recycling for cement production has negative effects on reducing all material flows except solid wastes. Thus, other fly ash utilization methods should be exploited. In addition, the utilization and treatment of secondary wastes from food waste recycling and sludge recycling should be concerned.