Introduction : Global dairy production has expanded significantly in recent decades, leading to increased generation of dairy by-products and highlighting the need for sustainable management solutions. Life Cycle Assessment (LCA) is attracting increasing amounts of attention as a key tool for evaluating environmental performance and supporting circular economy strategies. This study aims to assess and compare alternative valorization pathways for dairy by-products, focusing on environmental impacts and circularity performance to identify resource-efficient and sustainable options.

Methods: LCA was applied to multiple valorization strategies using a functional unit of 1 kg of processed raw milk to ensure a consistent comparison across scenarios. The examined pathways included (i) direct disposal (baseline), (ii) protein recovery via energy-intensive technologies, (iii) production of functional foods from whey, (iv) biogas generation with residue utilization, and (v) an integrated approach combining functional food production, biogas, and material recovery. The environmental impact categories comprised global warming potential, cumulative energy demand, water footprint, and eutrophication potential. Circularity assessment encompassed recovery rates and the Material Circularity Indicator (MCI).

Results: The results showed that protein recovery and functional food production enhanced circularity and reduced waste compared to the baseline, though some technologies increased the energy demand. The integrated approach demonstrated the most balanced performance, achieving both lower environmental impacts and higher circularity.

Conclusions: In conclusion, the proposed LCA framework provides a holistic evaluation of valorization pathways and supports informed decision-making for sustainable dairy by-product management. Further case studies are recommended to refine the methodology and validate its applicability across diverse production systems.