LCA for territorial metabolism analysis: An application to organic waste management planning

The management of biodegradable waste in landfills is associated to a range environmental impacts and refers to a linear model regarded as unsustainable. At the same time, many agricultural and urban soils present low organic matter content. Composting is emerging as a good practice for converting organic waste into a new resource able to improve soil properties, thus providing regulation Ecosystem Services. Considering a territorial metabolism perspective, this work discusses the potential contribution to regional planning of a transferable methodology for quantifying environmental impacts and benefits associated to waste management, based on a combined use of Life Cycle Assessment and Geographic Information Systems, and considering Ecosystem Services deriving from the application of compost in agricultural soils. The approach was tested through a site-dependent analysis based on primary data, referring to year 2019 and focusing on the Veneto Region, Italy. Results indicate that direct benefits associated to the use of compost and the thermal energy to district heating are compensating from 29 % to 51 % of the impacts associated to compost production, while waste transports represent the largest share of the impacts, covering between 52 % and 78 % of the total flows considered. The proposed methodology is applied for comparing the reference condition to alternative scenarios, in the perspective of providing support in Strategic Environmental Assessment procedures. In this context, results shown markedly lower impacts associated to compost production, with respect to organic waste treatment, for 5 out of 6 of the considered categories (freshwater eutrophication 100:1, climate change 5:1), with the notable exception of water resource depletion. Scenarios produced are discussed with respect to the choice between centralized and non-centralized plants, and the characterization of potential benefits at the territorial scale associated to compost use for urban green infrastructures. With respect to this latter point, results showed an underdeveloped use of compost-related ES flow, compared to its capacity, suggesting an interest for further research aimed at estimating compost requirements by urban and peri-urban soils.