Enhanced removal of gaseous 1,3-dichlorobenzene in biotrickling filters by rhamnolipid and Mg (II)

In this study, the effect of rhamnolipid and Mg (II) on microbial growth and 1,3-dichlorobenzene removal was investigated in two identical lab-scale biotrickling filters (named BTF1 and BTF2). The contact angle and Henry's constant were detected at various concentrations of rhamnolipid and the results indicated that rhamnolipid is able to effectively improve the solubility of 1,3-dichlorobenzene in medium. The results of the experiments in BTFs showed that the optimal concentrations of rhamnolipid and Mg (II) were 170 mg/L and 2 mg/L, respectively. The removal efficiency (RE) of 1,3-dichlorobenzene decreased from 100% to 57.13% for BTF1 that was not fed with rhamnolipid and Mg (II) and from 100% to 86.26% for BTF2 that was fed with rhamnolipid and Mg (II) when the inlet loading rate increased from 2.87 to 83.83 g/(m3 h) at an empty bed residence time (EBRT) of 60 s. The dissolved oxygen (DO) was analyzed throughout the entire period and the results showed that the two additives can significantly promote oxygen transfer. In addition, the microbial adhesive strength and community were observed and compared to show the positive role of rhamnolipid and Mg (II).