Kinetics and biotransformation products of bisphenol F and S during aerobic degradation with activated sludge

Bisphenol F (BPF) and bisphenol S (BPS) are becoming widespread in the environment despite the lack of information regarding their fate during wastewater treatment and in the environment. This study assessed the biodegradation kinetics of BPF and BPS during biological wastewater treatment with activated sludge using GC-MS/MS, and the identification of biotransformation products (BTPs) using LC-QTOF-MS. The results showed that BPF and BPS degrade readily and unlikely accumulate in biosolids or wastewater effluent (c_i = 0.1 mg L^-1, half-lives <4.3 days). The first-order kinetic model revealed that BPF (k_t = 0.20-0.38) degraded faster than BPS (k_t = 0.04-0.16) and that degradation rate decreases with an increasing initial concentration of BPS (half-lives 17.3 days). The absence of any additional organic carbon source significantly slowed down degradation, in particular, that of BPS (lag phase on day 18 instead of day 7). The machine-learning algorithm adopted as part of the non-targeted workflow identified three known BTPs and one novel BTP of BPF, and one known and ten new BTPs of BPS. The data from this study support possible new biodegradation pathways, namely sulphation, methylation, cleavage and the coupling of smaller bisphenol moieties.