Circular Valorization and Biochar Based Treatment of Agro-Industrial Effluents: Insights from the VALCARB Project

In response to growing environmental challenges linked to agro-industrial wastewater management, the VALCARB project aims to develop a real-world circular economy model through the valorization of agricultural residues for the production of eco-friendly biosorbents dedicated to wastewater treatment. We carried out comprehensive analyses to characterize the organic, saline, and microbiological pollution of effluents collected from the Société des Boissons de Tunisie (SBT) and its discharge site. The results revealed high electrical conductivity (9,420 μS/cm), chloride levels (2,455 mg/L), and chemical oxygen demand (COD ≈ 820 mg O2/L), indicating severe salinization and organic loading, with potential risks of soil degradation. Microbiological analyses confirmed fecal and fungal contamination, including Trichoderma, Penicillium, Alternaria, and Aspergillus species. Conversely, treated wastewater samples showed a marked improvement in quality, with COD reduced to 90 mg O2/L and conductivity below 2,400 μS/cm, demonstrating partial effectiveness of the biological treatment system. Simultaneously, biochars produced from olive residues showed high specific surface areas (200-300 m2/g) and a porous structure suitable for pollutant adsorption, suggesting strong potential for effluent purification. These preliminary results highlight the synergy between biomass valorization and wastewater remediation, supporting the development of sustainable agroecological solutions for arid and semi-arid regions of Tunisia.