Algae-based fertilizers from recycled nutrients: legal framework and sustainability

Algae-based fertilizers produced from recycled nutrients in urban wastewater, aquaculture effluent, and manure digestate are assessed for compliance with EU Fertilizing Product Regulation and organic farming standards. The study examines legal pathways for solid and liquid organic fertilizers (PFC 1.A.I, 1.A.II) and non-microbial biostimulants (6.B), with nutrient content of 2.5% N, 2.0% P₂O₅, and 2.0% K₂O. Drying is required for solid forms. Regulatory frameworks under Regulation (EU) 2018/848 and (EU) 2021/1165 are analyzed, including criteria for organic certification, sustainable sourcing, and exclusion of sewage sludge and animal by-products unless properly treated. The project, led by s.Pro sustainable projects and Ghent University, evaluates legal, environmental, and economic dimensions, with recommendations for market integration of algae-based fertilizers in organic farming and aquaculture.