Biofilm properties on carriers for wastewater treatment: Supporting Green Deal

The European Green Deal necessitates the development of innovative, sustainable, and resource-efficient biotechnologies in the wastewater sector. Biofilm carriers are central to this goal, enabling highly efficient biological treatment through microorganism immobilization. This study investigates the impact of carrier design on biofilm formation and performance by evaluating biomass accumulation and biofilm structure on three distinct polypropylene (PP) carrier types (A, B, and C) under controlled laboratory conditions. Immobilized biomass was quantified using gravimetric analysis, while the three-dimensional structure and composition were assessed via Confocal Laser Scanning Microscopy (СLSM). Results demonstrated that Carrier "B", featuring a corrugated PP structure, was the most favorable for microbial growth, exhibiting the highest volumetric biomass accumulation 176 mg/dm 3 ) and the largest effective surface area (5255 cm 2 ). Conversely, the PP mesh (Carrier "C") showed the lowest total accumulation but the highest biomass density per unit surface area. CLSM analysis revealed significant structural variations, including cellulose content reaching up to 86 % in mature biofilms, highlighting the complex role of Extracellular Polymeric Substances (EPS) in stability. These findings confirm that carrier geometry is a critical factor influencing microbial density and metabolic zoning, indicating that Carrier "B" provides the most efficient platform for enhancing aerobic wastewater treatment processes in support of Green Deal innovations. This conclusion was also confirmed by the results of wastewater treatment for organic matter and ammonia nitrogen.