Fig. 6. (A) S-plot generated by comparison of microbial communities in A1 and O1 of the first stage A/O process. (B) S-plot generated by comparison of microbial community in A1 and A2 of two anoxic biological reaction tanks. (C) S-plot generated by comparison of microbial communities in A2 and O2 of the second stage A/O process. (D) S-plot generated by comparison of microbial community in O1 and O2 of two oxic biological reaction tanks.