Life Cycle Assessment of Bioconversion of Agri-Food Production Residues: Evaluation and Improvement of Energy and Environmental Sustainability

This thesis evaluates the environmental performance of frozen horticultural production systems and explores the potential of Black Soldier Fly Larvae (BSFL) bioconversion as an innovative approach to agro-industrial residue valorization. Using the Life Cycle Assessment (LCA) method, the study identifies key environmental hotspots across the horticultural supply chains. Primary data were collected from a representative Italian agricultural consortium specializing in frozen vegetable production. The findings reveal that cultivation is a major contributor to environmental impacts, particularly in integrated farming systems, due to agrochemical inputs and related emissions. While organic farming showed relatively lower environmental impacts, limitations like small sample sizes necessitate further research to ensure robust comparisons. Processing phases were also identified as hotspots, driven by energy-intensive operations and relative low transformation efficiency. Valorizing these residues can improve system sustainability. BSFL bioconversion was evaluated as a residue valorization strategy to produce insect biomass. A mass rearing prototype system was designed and tested with the residues and liquid digestate. While results showed promising substrate reduction and larval growth performance, environmental impacts were dominated by electricity for climate control. BSFL protein and fat had higher impacts than conventional protein and fat sources. BSFL also had a higher impact than anaerobic digestion (AD) for residue management. Integrating residual heat from AD emerged as a key strategy to reduce these impacts and make BSFL competitive. The study also identified synergies between BSFL and AD, where BSFL frass serves as a feedstock for biogas production, further promoting circularity. Despite its current challenges, such as high energy consumption and regulatory barriers, BSFL can be a sustainable protein and fat option. The study underscores the importance of holistic approaches, including improving energy efficiency, adopting precision farming techniques, and integrating BSFL systems to enhance the environmental sustainability of frozen horticultural production chains. This work provides a basis for future studies to refine BSFL technologies and develop scalable and sustainable systems.