LCA-based comparison of two organic fraction municipal solid waste collection systems in historical centres in Spain

Municipal solid waste (MSW) collection is an important issue in the development and management of smart cities, having a significant influence on environmental sustainability. Door-to-door and pneumatic collection are two systems that represent a way of arranging waste collection in city´s historic areas in Spain where conventional street-side container collection is not feasible. Since door-to-door collection generates significant direct greenhouse gas emissions from trucks, pneumatic collection emerges as an alternative to the trucking system. While this technology apparently reduces local direct air emissions, it suffers from a large energy demand derived from vacuum production for waste suction. The introduction of new normative frameworks regarding the selective collection of the biodegradable fraction makes necessary a comprehensive analysis to assess the influence of this fraction collection and its subsequent recycling by anaerobic digestion. As a novelty, this work compares both conventional door-to-door and pneumatic collection systems from a life cycle approach focusing on the biodegradable waste. Results indicate that, in spite of the fact electricity production and consumption have a significant influence on the results, the energy savings from the recycling of the organic fraction are higher than the energy requirements. Therefore, the pneumatic collection could be an environmentally-friendly option for MSW management under a circular economy approach in Spanish city´s historic areas, since wastes could be a material or energy source opportunity.