Low-temperature thermal pretreatment enhanced the release
of SCOD and P from PGS more effectively than from PFS, due to
the greater EPS content in PGS and the higher ratio of P reserved
in EPS. PGS contains many more anaerobes and dead cells than
PFS; thus, SCOD and TVFAs were much more easily released from
PGS than from PFS during anaerobic fermentation. PGS fermentation
can facilitate the production of n-butyric acid. Furthermore,
due to the existence of some hydrogen-producing bacteria in PGS
such as Clostridium and Enterobacteriaceae_unclassified, hydrogen
tended to accumulate during PGS fermentation.