The initial PGS (PGS-I) and PFS (PFS-I) used in this experiment
were taken from two sequencing batch reactors (SBRs) that had
been running stably for 3 months in our laboratory. Detailed information
about the operation and performance of the SBRs is documented
in the Supplementary materials. After being taken from
the SBRs, the two types of sludge were settled and the supernatants
were discarded to concentrate the sludges. Then the thickened
sludges were stored at 4 C until used. The characteristics of
PGS-I and PFS-I are presented in