• circular economy
• combustion
• composite material
• micro-nano fibrillated cellulose
• paper mill waste
• PCL
• PLA
• pyrolysis
• strenght additive
• thermal treatment
• valorization

This PhD thesis explores different valorization strategies for waste generated by paper mills, from a circular economy perspective. It focuses on two key waste streams from paper production and investigates different methods for their recovery and reuse. Through a combination of thermochemical, chemical and mechanical treatments, the research demonstrates how these materials can be transformed into valuable products such as biofuels, fillers and composite materials. These approaches show promise for industrial application and contribute to improving sustainability, resource efficiency, and environmental performance in the paper sector.