Carbon footprint and life cycle economic costs of pilot Know-as-you-Throw schemes in Italy and Spain.

Considerable resources are spent globally on actions to improve the separate collection of municipal waste aiming to minimise the environmental and economic impacts of municipal waste management. One of such actions are know-as-you-throw (KAYT) schemes, which aim to change the behaviour of waste generators through tailored communication of information. KAYT schemes offer a relatively uncontroversial and simple tool, yet their environmental and economic performance remains unknown due to their limited implementation. To fill this gap, the LIFE-funded REthinkWASTE project applied a novel KAYT scheme in four pilot areas in Italy and Spain. The results of such pilots were evaluated in terms of carbon footprint and life-cycle costs of municipal waste management. The carbon footprint was notably reduced in all pilot areas, ranging from a 46% to 19% reduction, mainly due to notable reductions in unsorted waste (between 10 and 17% reduction) and subsequent lower treatment impacts. Life-cycle costs slightly increased overall, ranging from 4.6% to a -0.4% change. In addition to various sources of uncertainty, self-selection and recency biases are highlighted as major sources for potentially overestimating the benefits of KAYT in the context of large-scale and long-term KAYT implementation. The results however consistently show that the additional carbon footprint from KAYT actions can be offset with less than a 5% reduction in unsorted waste, well below the observed values. The results robustly reveal the potential of KAYT to notably reduce the carbon footprint of waste management systems with limited investment of economic resources.