Feast-famine moving bed biofilm reactors (MBBRs) have shown high potential for removing organic micropollutants
from wastewater. However, the relationship between biofilm community during feast-famine adaptation
and micropollutant removal is yet unclear. In this study, we determined the biotransformation kinetics of
36 micropollutants and characterized the microbial communities in an MBBR during a 71-day adaptation period
of feast-famine regime (raw/effluent wastewater). The feast-famine regime significantly changed the biodegradation
rate constants (k) of 24 micropollutants in different ways: 66 times enhanced degradation for propranolol,
while more than 10 times for atenolol, metoprolol, tramadol and venlafaxine, less than 2.8 times for losartan,
iomeprol and iohexol were detected. 25–60 days of adaptation time was needed to reach the maximum k. Biofilm
accumulated during the adaptation, but the kDNA (k relative to the biofilm with DNA concentration as a proxy for
kbiomass) of most micropollutants (except propranolol, metoprolol and venlafaxine) declined. This might indicate
that the proliferation of potential degraders for micropollutants was slower than other microorganisms under the
feast-famine regime. The microbial community changed significantly during the first 8 days of operation, followed
by a relatively steady evolution towards the enrichment of nitrifiers until day 71. A multivariate statistical
correlation analysis revealed that the development of occurrence of 88 individual taxonomic groups were found
to exhibit a significant positive correlation to the kDNA of micropollutants (p < 0.05, r > 0.5), which represent
potential biomarkers linking to biotransformation of micropollutants. These results fill the knowledge gaps between
dynamics of biofilm communities and micropollutant removal in the feast-famine regime, which is
essential for designing highly efficient MBBR.
