The SEA2LAND project is a 4-year collaborative Innovation Action (IA) funded by the EU in the frame of the Horizon 2020 programme. Based on the circular economy model, SEA2LAND promotes the production of fertilisers in the EU from its own raw materials. This solution is expected to reduce the soil nutrient imbalance in Europe. The basis of the project is the regional production of bio-based fertilizers (BBF) from fishery and aquaculture by-products by developing dedicated demonstration pilots that can be replicated across Europe, boosting local growth. 26 partners from 11 countries are participating in the project. 9 technologies are developed on the basis of 7 demonstration pilots implemented in 6 representative areas of the European fishing and aquaculture sectors. For the Atlantic area case study, the project aims at producing BBF’s from fish by-products1 using ThermoMechanoChemical (TMC) fractionation by twin-screw extrusion as innovative process. TMC process is a continuous process, working at low liquid/solid ratios and able to provide a solid and a liquid fraction 2.The use of TMC process for BBF’s production is an innovative approach that makes it possible to recover not only products with an agronomic value but also other components such as lipids to reach a ZERO-wasteprocess. The process was developed on the fractionation of heads and frames of Steelhead trout’s (Oncorhynchus mykiss), provided by a fish farm (Pisciculture Ispeguy, French Basque country). The N, P, K, and lipids contents in raw materials were respectively of 6.8%/DM, 1.4%/DM, 0.54%/DM and 42.5%/DM for heads and 6.9%/DM, 1.9%/DM, 0.62%/DM, 46.5%/DM for frames. The Atlantic pilot integrates the TMC extruder as principal technological unit but also includes pretreatment units and downstream processes. The TMC fractionation process was optimized at lab scale studying the twin screw extruder configuration and the influence of temperature, screw profile, screw speed or enzymes introduction on the yield in BBF’s and the yield in lipids recovery and on BBF’s composition (total N and residual lipids). The process developed at lab scale at a feed rate of 5-10 kg/h was scaled to pilot scale at a feed rate of 20 kg/h and at an industrial pilot scale at a feed rate of 100-200 kg/h. Two fertilizing products were obtained for the Atlantic Area: i) an organic solid BBF (9% N/DM), ii) a liquid organic fertilizer (11% N/DM). Both were directly tested in pot trials without formulation and the solid BBF was retained for field trials. Moreover, the TMC process generates as highly valuable co-product an oily phase. This oil, rich in omega 3 (5.1% in EPA+DHA) but also in astaxanthin (11 mg/kg), a red carotenoid, could be used in food and feed sectors 3.