Abstract: A kind of immobilized bio-filler (BM filler) was prepared by immobilization technology, combining polyvinyl alcohol (PVA) and sodium alginate (SA) to construct a gel skeleton, introducing activated carbon (AC), CaCO₃, and composite bacterial powder, and optimizing the particle size of AC added to BM filler. The removal effect of the biological trickling filter (BTF) packed with the filler was investigated using ethylbenzene as the target pollutant. When the added AC was 100 mesh, the specific surface area of BM filler reached 57.46 m²/g with the highest mechanical strength and the best degradation effect on ethylbenzene. The results of physicochemical properties analysis showed that the filler had a dense three-dimensional internal mesh structure, with good hydrophilicity and adsorption capacity, and a large number of hydrophilic groups such as —OH and —COO⁻ on the surface, and the adsorption of ethylbenzene was 2.9 times higher than that of polyurethane sponge (PU) filler under the same conditions. Meanwhile, the filler had good acid resistance and still maintained a high degradation activity when pH dropped to 1. The BTF packed with BM filler could be started up in 6 days; after 7 days of stagnation, the removal efficiency recovered to 100% in 5 days; and ethylbenzene could still be completely removed at the inlet ethylbenzene concentration of 800-900 mg/m³ and the empty bed residence time (EBRT) of 33 s. Compared with the BTF packed with PU filler, the BTF packed with BM filler showed superior performance.