Denitrification aided by waste beer in anaerobic sequencing batch biofilm reactor (AnSBBR)

•Waste beer was a source of carbon in denitrification process in AnSBBR.•A close to 100% denitrification efficiency was observed.•The biomass growth was ten times lower than in suspended biomass reactors.•Trichococcus was the dominant microorganism in an AnSBBR supplied with waste beer.

The goal of research was to examine waste beer as a source of carbon in an anaerobic sequencing batch biofilm reactor (AnSBBR). It was demonstrated that waste beer enhanced denitrification. Observed biomass yield coefficient (Yobs) was one size of magnitude lower than for suspended-biomass reactors (0.03 ± 0.03 mgTSS mgCOD−1). The kinetic parameters (utilization of organic substrate and denitrification rates) were lower during the start-up period (88.8 mgO2 L−1 h−1 and 17.37 mgN L−1 h−1, respectively) than during stable operation of the reactor (212.4 mgO2 L−1 h−1 and 34.66 mgN L−1 h−1 after 180 cycles). The metagenomic results showed that the abundance of Alcaligenes decreased from 18.39% to 0.88% (in 180 cycle), whereas the read numbers of Trichococcus increased gradually from 2.93% to 52.26% (in 180 cycle). Trichococcus was the dominant microorganism (52.3%). The low value of Yobs most likely resulted from the ability of Trichococcus to degrade complex organic compounds and extracellular polysaccharide substances (EPS), released from dead cells in deeper layers of the biofilm.