H.-L. Jiang and J.-H. Tay (Singapore)
Aerobic Granules; Bioaugmentation; Coexistence; Competition; Spatial Effect
This study examined the feasibility to simultaneously bioaugment two competitive strains in aerobic granules. In spatially homogeneous batch conditions, strain PG-01 with higher growth rate outcompeted strain PG-03. However, the two strains could stably coexist in spatially heterogeneous conditions. To assess the survival capacity of the two strains in complex microbial communities, the two strains were mixed and bioaugmented into activated sludge in two sequencing batch reactors operated with the different settling times. Aerobic granules were developed only in the reactor with a short settling time of 5 min. While growth advantage for strain PG-01 was obvious in the initial phase, strain PG-03 may have a chance to become dominant in the aerobic granules in the maturation phase. In contrast, strain PG-03 was not detected within activated sludge in the reactor with a long settling time of 30 min during the experimental period. These findings suggested that the aerobic granule structure provided niches for existence of inferior competitive strains compared to activated sludge. Therefore, it is possible to bioaugment a group of strains with similar functions but competitive interaction in aerobic granules for creating a new kind of robust biocarriers.
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