Bioaugmenting a Lab-Scale Membrane Bioreactor with 4- tert -butylphenol-degrading Bacterium, Sphingobium fuliginis OMI

Abstract

This study demonstrated the bioaugmentation of a lab-scale membrane bioreactor (MBR) that enhanced 4-tert-butylphenol (4-t-BP) elimination by Sphingobium fuliginis OMI, which utilizes 4-t-BP as its sole carbon source. The control MBR, without bioaugmentation, needed an acclimation period of over 1 month to eliminate 4-t-BP with the help of indigenous 4-t-BP degraders. Contrastingly, the bioaugmented MBR removed 4-t-BP from the influent (10-20 mg/L) to less than the detection limit (< 1 mg/L) within 7 days, and maintained 4-t-BP elimination until day 35. According to the real-time polymerase chain reaction quantifications of the catechol 2, 3-dioxygenase genes, the bioaugmented MBR maintained larger amounts of the genes until day 17 when compared to the control MBR, which indicated the survival of strain OMI in the bioaugmented MBR during the period. These results verified that MBRs had superiority for bioaugmentation as they prevented the introduced strains from washing-out. However, more frequent membrane fouling occurred in the bioaugmented MBR, which could be induced by strain OMI. The results suggested that membrane fouling is an important factor to be addressed for successful bioaugmentation in an MBR.