Enhanced biofilm formation and municipal wastewater treatment efficiency using granular activated carbon modified bio-ball carriers in moving bed biofilm reactor

This study introduces a novel enhancement to biological wastewater treatment by integrating Granular Activated Carbon (GAC) with plastic bio-balls in a Moving Bed Biofilm Reactor (MBBR) configuration treating municipal sewage. The resulting GAC-MBBR system demonstrated significantly improved treatment efficiency, achieving 81.8 % carbon and 74.9 % nitrogen removal under high loading conditions-outperforming the conventional plastic-MBBR (64.5 % and 62.7 %, respectively). The macroporous structure of GAC provided increased surface area, promoting superior biofilm growth and microbial retention. Enrichment of key functional genera, including Zoogloea, Thauera, Nitrospira, and Nitrosomonas, was observed, indicating enhanced nitrification potential. Additionally, greater biomass accumulation on GAC carriers underscored their effectiveness in supporting microbial aggregation. These findings suggest that incorporating GAC into MBBR systems offers a promising strategy to optimize biofilm development and improve nutrient removal in wastewater treatment.