Effect of rhamnolipids on the biodegradation of m-dichlorobenzene in biotrickling filters: Performance and mechanism

In this study, the effect of rhamnolipids (RL) on m -dichlorobenzene ( m -DCB) removal and biofilm was investigated in two biotrickling filters (BTF) (BTF1: blank control; BTF2: RL addition). The critical micelle concentration (CMC) value of RL was 75.6 mg L −1 , and the RL could significantly improve the solubilization of m -DCB. The results showed that the optimal concentration of RL was 180 mg L −1 . The removal efficiency (RE) of m -DCB dropped by 42.4% for BTF1 no fed with RL and only 28.2% for BTF2 fed with RL when the inlet concentration increased from 200 to 1400 mg m −3 at an empty bed time (EBRT) of 60 s. RL increased the secretion of extracellular polymers (EPS) and the ratio of Protein/Polysaccharide, which improved the mass transfer of m -DCB to the biofilm. RL also had a facilitating effect on catechol-1,2-dioxygenase (C 12 O) enzyme activity . Furthermore, RL increased Zeta potential and facilitated microorganisms to form biofilm . The dominant microorganisms of microbial community were increased and the application of RL promoted the enrichment of them.