Synergistic removal of m-xylene and its corresponding mechanism in a biotrickling filter

Synergism is an important strategy to enhance the bioavailability of pollutants and optimize biotrickling filter (BTF) performance. The synergistic biodegradation of m- xylene with the introduction of toluene was investigated in this study. The packing was diatomaceous earth pellets with a volume of 2411 cm 3 . The empty bed residence time (EBRT) of the BTF was kept constant at 25 s. The mixing ratios for toluene and m- xylene were 1:1, 1:2, 1:4, and 1:6, corresponding to the inlet loading rate (ILR) of m- xylene from about 36 to 216 g/m 3 /h, and the toluene ILR was maintained at about 36 g/m 3 /h. The biodegradation performance and biofilm characteristics were evaluated under these various mixture compositions. For mixing ratios of 1:1, 1:2, and 1:4, m- xylene was synergistically removed with toluene. The most pronounced synergism occurred when the ratio was 1:2; the average elimination capacity (EC) of m- xylene increased by 12.5%, from 64 g/m 3 /h to 72 g/m 3 /h. The presence of toluene promoted the growth of microorganisms and improved the hydrophobicity of the biofilm. In contrast, for the 1:6 toluene and m- xylene mixture, toluene inhibited the degradation of m- xylene. The microbial species composition analysis revealed that Burkholderia and Mycobacterium were correlated with synergistic removal of m- xylene, especially Burkholderia . • m- xylene was synergistically removed with toluene in a biotrickling filter. • Toluene stimulated microbial growth and biomass accumulation synergistically. • Toluene synergistically improved the hydrophobicity of biofilms. • Burkholderia correlated with synergistic removal of m- xylene.