The spatial community succession of an anaerobic baffled reactor with the variation of hydraulic retention time

Abstract A 28.4 L anaerobic baffled reactor (ABR) with four compartments was used to study the spatial community succession and the effect of hydraulic retention time (HRT) on the microorganism distribution. Furthermore, it was determined whether an ABR would promote bio-phase separation with the variation of hydraulic retention time. The high-throughput sequencing technology was used to analysethe bacteria and archaea communities in the ABR with HRT of 1.7 and 0.7 d. At the phylum level, Bacteroidetes, Euryarchaeota, Proteobacteria and Firmicutes were dominant in the bacteria community. At the family level, the distribution of bacteria and archaea communities varied in four compartments. The percentage of acetotrophic methanogens linearly increased with the compartments number. In contrast, hydrogenotrophic methanogens linearly decreased along with the compartments. The shortened HRT resulted in a decrease of acetotrophic methanogens percentage, but an increase of hydrogenotrophic methanogens in the last compartment. At HRT of 1.7 d, COD removal and methane yield of ABR were 93.4% and 16.3 L d−1, respectively. As HRT shortened to 0.7 d, COD removal and methane yield decreased to 87.7% and 12.7 L d−1, respectively. The treatment efficiency and bio-phase separation of ABR were weakened by the shortened HRT.