## 6 Conclusions  
Digestate represents a key resource within the circular bioeconomy, standing out as a valuable biofertilizer capable of enhancing soil fertility and reducing dependence on synthetic fertilizers. However, its efficient utilization requires appropriate treatment and application strategies to maximize agronomic benefits while minimizing adverse environmental impacts. LCA studies reveal significant variability in results due to differences in functional unit selection and system boundaries. Feedstock type, pretreatment methods, and post-processing strategies influence nutrient retention, fertilization potential, and digestate-associated emissions. Implementing post-treatment strategies, such as solid-liquid separation and composting, has proven effective in improving digestate stability and optimizing agronomic properties. Proper soil application can mitigate eutrophication risks, enhance soil structure, and reduce greenhouse gas emissions, particularly ammonia and nitrogen oxide losses. However, digestate's economic and environmental feasibility depends on transportation distances and application methods. Studies indicate that when transport exceeds 15 km, the environmental benefits may be offset by increased emissions and energy use. Additionally, direct soil injection has been identified as an effective strategy to minimize NH\({}_{3}\) volatilization and reduce nitrate leaching. The selection of digestate vaporization processes also involves important environmental trade-offs. Converting digestate into hydrochar enables significant carbon sequestration (15-30%), reducing long-term global warming potential. While composting extends processing time, it stabilizes nutrients and enhances fertilizer efficiency. In contrast, direct application of liquid digestate poses a higher risk of nitrate leaching and water contamination. An anaerobic digestion remains the most effective strategy for obtaining carbon credits, primarily due to its role in replacing fossil fuels. Increasing anaerobic digestion efficiency through technologies such as electro-digestion can reduce system-wide emissions by up to 35.9%, although it entails higher initial energy consumption. Finally, LCA studies demonstrate that the choice of the functional unit and the scope of the analysis significantly impact results, limiting direct comparability between studies. Research focusing on biogas production (MJ or m\({}^{3}\) of methane) and those prioritizing fertilizer substitution (kg of digestate, NPK content) reach different conclusions regarding digestate sustainability. Similarly, system boundaries, including infrastructure and transportation, greatly influence the final environmental impact values. To promote digestate vaporization and consolidate its role within the circular economy, it is crucial to implement policy incentives and standardize LCA methodologies. These measures will facilitate its optimal utilization, enhance its competitiveness against conventional alternatives, and ensure sustainable organic waste management. Furthermore, developing robust markets for digestate-derived products will drive their large-scale adoption. To conclude, the following action points summarize key recommendations for stakeholders and decision-makers:  
* Promote the development and adoption of standardized LCA methodologies to improve comparability and transparency. * Incentivize digestate post-treatment strategies (e.g., composting, separation) to enhance agronomic quality and environmental safety. * Establish clear policy frameworks and end-of-waste criteria to enable digestate commercialization. * Support research on digestate behavior under diverse agronomic and climatic conditions. * Strengthen regional digestate markets through public procurement, farmer training, and quality certification schemes. Conceptualization, C.M.-S.-G., M.R.-A. and C.M.-P.; methodology, C.M.-S.-G.; validation, M.R.-A., A.M.S.-M. and C.M.-P; formal analysis, C.M.-S.-G., M.R.-A. and C.M.-P.; investigation, C.M.-S.-G., M.R.-A., A.M.S.