ONE EARTH aims to develop and assess innovative bio-based solutions for the production of nutraceutical/cosmetic, bioadhesive, agriculture (fertilizers), and aquaculture (fish feed) products by exploiting residual biomass of animal origin. The overall purpose of ONE EARTH is to develop integrated circular value chains by valorising marine biomass for terrestrial products and using terrestrial biomass for aquaculture product production thus promoting a sustainable and "self-reinforcing" carbon cycle. ONE EARTH will obtain polyunsaturated fatty acids (PUFAs) and polypeptides that make up nutraceuticals, cosmetics and fish feed products through the transformation of specific residual biomass, mainly using biotechnological strategies. In particular, cheese whey (CW), i.e., the most abundant liquid waste from dairy industries, will undergo anaerobic acidogenic fermentation processes for the production of volatile fatty acids (VFAs), which will be used as a carbon source for the production of PUFAs by culturing pure microbial strains. A massive valorisation of CW carbon will be assured by exploiting CO2-rich gaseous streams from fermentation processes for cultivation of algae and further extractions of PUFA. Moreover, chicken feathers and fish scales will be processed using microbial and enzymatic approaches to obtain polypeptides, while fishbones will be treated with a thermochemical innovative process together with organic residues from other project units to produce Phosphorus-rich fertilizers. Dedicated standard tests in significant environments will be carried out to evaluate the safety and quality of developed products. Consequently, the economic, environmental and social sustainability and viability of the whole proposed integrated circular value chain will be assessed. The compliance with standards and regulations of developed solutions will also be considered to assess the project potential and opportunities to promote industrial initiatives and new business.