ELLIPSE project will address the valorisation of two heterogeneous waste streams generated in significant amounts in Europe, slaughterhouse waste (bellygrass or rumen content) and paper and pulp sludge, to produce cost-efficient polyhydroxyalkanoates (PHAs) for agricultural and personal care applications, by the coprocessing with other organic wastes (OW) such as sludge from the dairy industry and glycerol from the biodiesel industry, as well as recovering nutrients to produce bio-based fertilizers (BBFs). The integration of these waste streams as biorefinery feedstocks will allow reducing the volumes of landfilled waste, opening new avenues for platform chemicals and bioplastics production while creating additional revenue for the related industries generating them, with added advantages of water recycling, decreased soil degradation, groundwater pollution and methane emissions.