Fig. 4
Phylum- and class-level structural changes of the microbial community during HRT operations under the neutral (a) and acid (b) conditions. Samples obtained at each depth of the reactor (top and ports 1–4) were analyzed by high-throughput sequencing of 16S rRNA genes. The phylogenetic groups are indicated by colors and their taxonomies are shown in the upper section of the graph. The color version of this figure is available online