In this study, a water–silicone oil biphasic system was developed to enhance the biodegradation of monochlorobenzene (CB) by Delftia tsuruhatensis LW26. Compared to the single phase, the biphasic system with a suitable silicone oil fraction (v/v) of 20% allowed a 2.5-fold increase in the maximum tolerated CB concentration. The CB inhibition on D. tsuruhatensis LW26 was reduced in the presence of silicone oil, and the electron transport system activity was maintained at high levels even under high CB stress. Adhesion of cells to the water–oil interface at the water side was observed using confocal laser scanning microscopy. Nearly 75% of cells accumulated on the interface, implying that another interfacial substrate uptake pathway prevailed besides that initiated by cells in the aqueous phase. The 8-fold increase in cell surface hydrophobicity upon the addition of 20% (v/v) silicone oil showed that silicone oil modified the surface characteristics of D. tsuruhatensis LW26. The protein/polysaccharide ratio of extracellular polymeric substances (EPS) from D. tsuruhatensis LW26 presented a 3-fold enhancement. These results suggested that silicone oil induced the increase in the protein content of EPS and rendered cells hydrophobic. The resulting hydrophobic cells could adhere on the water–oil interface, improving the mass transfer by direct CB uptake from silicone oil.

The continuous emissions of volatile organic compounds (VOCs) from the industrial process cause serious environmental problems and pose a threat to human health. Photodegradation technology and biofiltration technology are efficient to control VOCs emissions. Recently, the researches on combined photodegradation and biofiltration technology have been attractive, since it could overcome the challenges in the application of the separated technologies, such as toxic by-product emission, excess biomass accumulation, and shock loading. However, no review has published to report the development of the combined technology comprehensively. In this paper, the challenges of the separated photodegradation and biofiltration technology in treating VOCs are documented firstly. Then, the advantages of the combined technology are illustrated by comparing with the separated photodegradation and biofiltration technology, respectively. Finally, the interaction mechanisms between photodegradation and biofiltration are also discussed. The advantages of the combined technology could promote its application in practical engineering. Graphical Abstract