The ABP Regulation allows different applications for Category 2 animal by-products. However, in practice, these by-products are almost exclusively used for energy production (which is the last resort recommended by the EU’s Circular Economy strategy) or are disposed of in authorised landfills, while Category 3 products are mainly used for the manufacturing of animal feed. Conversely, the LIFE byProtVal project proposes the use of these by-products as a raw material for the production of two higher added value products: retanning agents and amino acid-based fertilisers or biostimulants. Design, construction and set-up of demonstration plants for the treatment of greaves and processing water.