Environmental sustainability assessment: from fruit and vegetable waste to earthworm as feed sources

Europe’s reliance on imported protein to feed livestock, particularly soybean, is inconsistent with sustainability objectives. Increasing dependence on soybean can lead to increasing environmental burden such as deforestation and greenhouse gas (GHG) emissions due to its transport over long distances, which contributes to climate change. In particular, soybean produced in South America embeds a considerable impact in terms of greenhouse gas emissions related to land use change and indirect land use change. At the same time, food waste has already been recognised as an important global issue. On the environmental point of view, food waste has led to unnecessary exploitation of natural resources (land, water and fossil energy) and to GHG production. Reduction and recycling of food waste is a key driver towards sustainable productive solutions. Among the possibilities to achieve this goal, this study explores the recycling of fruit and vegetable waste (FVW) discarded directly from juice and ready-to-eat food processing industries, as a growth substrate for producing fresh earthworms then processed into a dried meal. The dried meal is assumed adoptable for feed alternative purposes, which is the studied scenarios. The aim of the present study is to assess the environmental impact of the bioconversion of FVW into earthworms dried meal as new feed source adopting the Life Cycle Assessment (LCA) method with an attributional approach and economic allocation. With LCA, other than the most widely known Climate Change expressed as kg CO2 eq., several indicators of environmental impact are considered, among which particulate matter formation (PM), photochemical ozone formation (POF) and freshwater eutrophication (FE). By means of LCA, the environmental impact of the production of the earthworm-dried meal was quantified. The results showed that climate change assessed for 1 kg of earthworm meal is 2.2 kg CO2 eq. The feed substrate for earthworms consists of FVW that, therefore, is highly valorised respect to waste. From this result, earthworms’ meal can represent a future-generation feedstock with improved sustainability in order to reduce the dependence on imported soybean as a protein source.