Chemical Engineering Journal, Vol.352, 214-224, 2018
Bioaugmentated activated sludge degradation of progesterone: Kinetics and mechanism
Progesterone (PGT) is not completely removed in conventional treatment plants, and the processing results may have adverse effects on aquatic organisms. In this study, an effective PGT-degradation bacterium, Rhodococcus sp. HYW, was newly isolated from the pharmaceutical plant and was used to augment degradation of PGT. When grown in a mineral medium (MM) containing a trace amount of PGT (500 mu g/L) as the sole carbon and energy source, the results show that 99% of PGT was degraded within 1 h and followed the first-order reaction kinetics. Bioaugmentation of PGT-contaminated activated sludge greatly enhanced the PGT degradation rate (similar to 91%) and its derivatives degradation rate were also greatly improved ( > 83%). The process of PGT degradation in non-bioaugmented PGT-contaminated activated sludge (NBS) and bioaugmentation activated sludge with the bacterial consortium(BS) also conforms to the first-order kinetic model. Furthermore, 12 and 11 biodegradation products for PGT in the NBS and BS were identified using HPLC-LTQ-Orbitrap XL (TM), respectively. Based on these biodegradation products, two degradation pathways for PGT in NBS and BS were proposed, respectively. Comparing the degradation kinetics and metabolites, it was found that BS degrades PGT more rapidly and can further convert PGT to a small molecular acid. Finally, to reveal the probable cause for the differences in the PGT degradation efficiency and products in the NBS and BS.