The objective of the project is to exploit the integration of the carbon, nitrogen and suflur cycles in bioreactors to design optimal treatment trains to recover added-value products out of liquid and gaseous effluents. The strategy will be to combine interdisciplinary approaches to: - investigate innovative unit processes based on partial nitrification for nitrogen recycle, autotrophic denitrification for biosulfur recovery and multienzyme-based bioreactors for CO2 valorization; - apply technologies that are novel in this field such as moving bed bioreactors, membrane biofilm reactors and enzimatic reactors - combine biological processes in to innovative treatment trains for wastewater treatment and biogas upgrading. The topic will be addressed from the point of view of circular economy by exploring the potential synergies of carbon, nitrogen and sulfur cycles in wastewater and biogas treatment trains to reduce treament costs and to te increase production of added-value products. From a methodological point of view, the project targets the improvement of existing knowledge of innovative technologies based on immobilized biocatalysts as well as the demonstration of the viability of innovative treatment trains at in-silico, lab- and pilot-scale levels. The project is interdisciplinary and intersectorial; in fact, the research teams involved include environmental and chemical engineers, biologists and bioinformatics and mathematical modellers, while the companies are complementary being specialised in reactors design and construction and in bioprocess design and control. Finally, the involvement of the industry will allow to receive feedbacks on the solutions needed from pilot case studies using real effluents and to effectively translate novel scientific outcomes into suitable technologies.