Waste-to-material recycling aimed to carbon based second generation materials: production technology and experimental application on several environmental matrices

This doctoral thesis investigates the multi-faceted applications of biochar as a sustainable, cost-effective alternative to traditional materials for environmental remediation within a circular economy framework. The research is structured into two primary lines: the engineering of Second-Generation Granular Activated Carbon (2G-GAC) for industrial wastewater treatment and the application of unmodified biochar in the phytoremediation of soils contaminated by Total Petroleum Hydrocarbons (TPH). The first line focuses on developing 2G-GAC from heterogeneous wood waste and industrial residues through steam activation at 850°C and an innovative agglomeration technique using phenol-formaldehyde resins and pre-carbonized bituminous sludge. The resulting materials achieved specific surface areas and mechanical resistance comparable to commercial activated carbon. Notably, the WP850-ATT sample reached 956 m²/g, exceeding that of traditional activated carbon. Batch adsorption tests and a scaled-up continuous-flow column experiment demonstrated high removal efficiencies for organochlorinated compounds. The study further clarified that system clogging was predominantly driven by physicochemical mechanisms, particle attrition, and inorganic salt precipitation, rather than biological biofilm formation. The second line evaluated the synergistic interaction between unmodified biochar derived from woody pruning (BC1) and sheep manure (BC2) and M. sativa for soil remediation. While 5% BC1 achieved the highest individual TPH degradation (36%), biochar integration proved essential for mitigating plant oxidative stress. Amendments significantly reduced malondialdehyde (MDA) levels and enhanced photosynthetic pigments, facilitating plant resilience in toxic, nutrient-poor environments. In conclusion, this research confirms that properly engineered or unmodified biochar represents a versatile and effective resource for environmental remediation. By bridging waste valorization and advanced remediation, the study provides a viable pathway for reducing the carbon footprint of industrial activities and restoring highly contaminated soil matrices.