The Sea2Land1 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 bio-based fertilizers (BBF) in the EU from its own raw materials in order to reduce the soil nutrient imbalance in Europe. The basis of the project is the regional production of 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-products2 using ThermoMechanoChemical (TMC) fractionation by twin-screw extrusion. Configured as an extraction process, extrusion represents an industrial continuous process able to provide simultaneously a solid and a liquid fraction 3. The use of TMC process for fertilizers production is an innovative approach that enables the recovery of not only BBFs with an agronomic value but also fish oil to reach a ZERO-waste process. The Atlantic process was developed on the fractionation of heads and frames of Steelhead trout. The biorefinery scheme integrates the extruder as main technology but also includes pretreatment units and downstream processes. The process was developed from TRL4 to TRL7 corresponding to feed rate in fish by-products of 5-10 kg/h and 100-200 kg/h respectively. From 1000 kg fish by-products, 2 fertilizing products are obtained i) 263 kg of an organic solid BBF (9% N/DM), ii) 320 kg of a liquid organic BBF (11% N/DM). Their agronomic efficiency was tested in pot trials without formulation and the solid BBF was retained for field trials. In addition, the process generates about 80 kg of fish oil highly prized by the human food and animal feed sectors 4. Sustainability was assessed by studying the environmental and socio-economic impacts of products. Environmental impacts were economically allocated, and the relative prices of oil and BBFs have therefore a major influence. The inventory of all process inputs and outputs and the use of SIMAPRO software with the Ecoinvent enable the identification of hot spots, which are mainly the electricity used for waste extrusion and the drying of solid BBF. Impacts can be compared with those of an NPK fertilizer with a comparable mineral content. In the case of climate change, the impacts are similar, but BBF has around 70% lower impacts for terrestrial acidification and freshwater eutrophication. For the social part, UNEP methodology5 was applied. The supply chain was assessed using Social HotSpot Database (SHDB) and semi-specific data on the fishing and chemical sectors in France. It reveals the importance of responsible sourcing and of certain social indicators, particularly in the impact categories dealing with health and safety. Besides, the impact on local economy are studied and business plans are defined.