The PROTEUS project aims to develop new products, alternative raw materials and technologies associated with the valorisation of by-products resulting from pulp and paper production, from a circular economy perspective. The by-products considered in PROTEUS are dregs, grits, fly ash and sludge (biological and calcareous), as well as specific liquid effluents (alkaline and D0 – procedural outflow streams). The new products to be developed are geopolymers, ecological geopolymer and food mortars, clinker and biochar, while the new technological applications are associated with the removal of halogenated organic compounds (AOX) which, at current concentration levels, present risks of rendering the production of the new products unfeasible due to the high levels of corrosion they cause. PROTEUS is an innovative proposal, both in concept and in the development of new products and technologies, given that the by-products from the start-up are currently not significantly valorised and, in addition to the associated costs, are factors of industrial inefficiency. In order to meet the objectives identified, the project is structured into 7 activities with Portucel S. A. as the lead promoter. Centro Fabril de Cacia, the Forest and Paper Research Centre – RAIZ, the University of Aveiro – UA and VentilAQUA S. A. as co-promoters and Saint-Gobain Weber as a partner.