Abstract: To elucidate the influence of carriers on the performance of Biological Aerated Filters (BAFs) in treating Reverse Osmosis Concentrate (ROC) from the petrochemical industry, this study constructed four parallel BAF reactors using dense granular activated carbon (Carrier 1), lightweight granular activated carbon (Carrier 2), columnar activated carbon (Carrier 3), and ceramic particles (Carrier 4).The continuous-flow experiment demonstrated that the physicochemical properties of the carriers were key to treatment performance. Carrier 2, with its high specific surface area (1001 m²/g) and rich pore structure, supported a biomass of 2.21 nmol P/g and a microbial activity of 9.43 μg/(g·h), achieving a TOC removal rate of 78.22%. In contrast, the reactor with Carrier 4, which had a specific surface area of only 0.95 m2/g, showed a TOC removal rate of just 7.37%.High-throughput sequencing results revealed that the reactor with Carrier 2 possessed higher community diversity and successfully enriched a microbial community dominated by functional bacterial groups such as Nitrospira (3.76%), Pseudomonas (3.34%), Phaeodactylibacter (1.88%), and Caldilinea (0.54%). This research provides a theoretical basis for the treatment of ROC in the petrochemical industry.

Key words: biological aerated filter, reverse osmosis concentrate, organic matter degradation, excitation-emission matrix fluorescence spectroscopy, activated carbon