Algal–Fungal Biofilms on Sardine Scale Supports for Fishery Effluent Bioremediation

Fishery effluents are often characterized by high organic and nutrient loads and require management planning based on a sustainable strategy. This study evaluated the efficiency of algal–fungal biomasses immobilized in a Moving Bed Biofilm Reactor (MBBR) using natural (sardine scales) or synthetic (Kaldnes K3) carriers. Several monocultures and mixed consortia were investigated for the treatment of wastewater generated by the fishery industry. The Gracilaria–Aspergillus niger consortium demonstrated the highest treatment performance. Nearly complete removal of COD and BOD5 within 24 h was recorded, accompanied by significant reductions in total nitrogen, nitrite, cadmium, and lead concentrations. After 72 h on K3 carriers, removal efficiencies for these four parameters reached approximately 90% or higher. The biofilm-bed performance of sardine scales was comparable to that of Kaldnes K3 under the experimental conditions tested, supporting their potential as a waste-derived biofilm carrier within a circular-economy framework. Kinetic modeling described pollutant removal using mono-exponential models, with fitted rate constants varying among treatment configurations and pollutants.