Impact of mixed microalgal and bacterial species on organic micropollutants removal in photobioreactors under natural light.

[Display omitted] • >30 % removal for 12 OMPs in both photobioreactors, while < 10 % removal for other 4. • 2 to 3 times higher removal capacity of 9 OMPs in mixed algae-bacterial community. • Predominance of filamentous green algae decreased the removal capacity of 9 OMPs. • Microbial community composition and abundance are important for OMPs removal. Single microalgae species are effective at the removal of various organic micropollutants (OMPs), however increased species diversity might enhance this removal. Sixteen OMPs were added to 2 continuous photobioreactors, one inoculated with Chlorella sorokiniana and the other with a microalgal-bacterial community, for 112 d under natural light. Three media were sequentially used in 3 Periods: I) synthetic sewage (d 0–28), II) 10x diluted anaerobically digested black water (AnBW) (d 28–94) and III) 5x diluted AnBW (d 94–112). Twelve OMPs were removed > 30 %, while 4 were < 10 % removed. Removal efficiencies were similar for 9 OMPs, yet the mixed community showed a 2–3 times higher removal capacity (µg OMP/g dry weight) than C. sorokiniana during Period II pseudo steady state. The removal decreased drastically in Period III due to overgrowth of filamentous green algae. This study shows for the first time how microbial community composition and abundance are key for OMPs removal. [ABSTRACT FROM AUTHOR]