Sustainable Urban Solid Waste Management from both Life Cycle and Urban Metabolism Perspectives

Urban solid waste management is an important component of urban sustainability. The concept of evaluating technologies from both life cycle and urban metabolism perspectives is proposed in this study. The analysis from life cycle perspective (using physical input-output life cycle assessment model) provides support for determining the priority of technologies, and the analysis from urban metabolism perspective (using physical input-output model) provides support for identifying the acceptability of technologies. Suzhou City in China is taken as an example. From urban metabolism perspective, sludge recycling is regarded as an accepted method, while current fly ash recycling method is unsatisfying. Technical levels of scrap tire recycling and food waste recycling should be improved to reduce their negative effects on Suzhou´s urban metabolism. From life cycle perspective, sludge recycling has the smallest environmental impacts, and scrap tire recycling has larger environmental impacts than food waste recycling does. Thus, more concerns should be paid to technical improvements of scrap tire recycling than to that of food waste recycling. The concept of evaluating technologies from both life cycle and urban metabolism perspectives in this study provides foundations for evaluating technologies in other countries and cities.