Augmenting the biodegradation of recalcitrant ethinylestradiol using Rhodopseudomonas palustris in a hybrid photo-assisted microbial fuel cell with enhanced bio-hydrogen production.

This study presents the biodegradation potential of ethinylestradiol (EE2) in anaerobic environments using exoelectrogenic activity of Rhodopseudomonas palustris. EE2, a basic ingredient in oral contraceptives, is a significant estrogenic micropollutant in various wastewaters and is considered highly recalcitrant. This recalcitrance of EE2 has caused anoxic areas to become repositories for these pollutants. Thus, it is essential to find the microorganisms and suitable methods to degrade this compound. An initial EE2 concentration of 1 mg/L, used in an anaerobic photobioreactor, resulted in 70% EE2 degradation over a period of 16 days with an increase of 63% in hydrogen production when EE2 was used with glycerol as the main carbon source in the culture medium. Furthermore, in the novel setup of hybrid photo-assisted microbial fuel cell (h-PMFC) employed here, EE2 degradation enhanced to 89.82% with a maximum power density of 0.633 ± 0.04 mW/m. The hybrid MFC employed here could metabolize EE2 and sustained the bio-hydrogen production for 14 days to run the hydrogen fuel cell which otherwise could not be sustained with glycerol only and thus increased the overall power output. The current work highlights the use of R. palustris and the significance of co-metabolism in bioremediation of pollutants and bioenergy generation.