posted on 2022-12-09, 22:29authored byHezhou Ding, Morton A. Barlaz, Francis L. de los Reyes, Douglas F. Call
The anaerobic digestion of food waste can yield valuable
volatile
fatty acids (VFAs), especially when methane (CH4) production
is inhibited. Selecting an inoculum with lower methanogenic populations
may help reduce CH4 production and improve VFA accumulation.
In this study, we investigated VFA and CH4 production in
short-term anaerobic batch bioreactors as a function of three inocula
compositions derived from a full-scale wastewater treatment facility:
(1) anaerobic sludge (AnS), (2) thickened waste activated sludge (TWAS),
and (3) TWAS with AnS. The highest VFA concentration (6.62 ±
0.08 g/L) and the lowest total CH4 volume (296 mL) were
measured with TWAS only. In contrast, the highest CH4 volume
(625 ± 3 mL) was measured in the TWAS + AnS, likely because the
AnS was well adapted to digesting TWAS. 16S rDNA sequencing showed
that TWAS alone had the lowest relative abundance of methanogens at
the start and end of the incubations. The addition of TWAS significantly
changed the initial community diversity. These insights suggest that
TWAS improves VFA accumulation by providing a microbial community
that is more diverse and lower in methanogen abundance relative to
AnS. These findings will help guide the selection of inoculation strategies
that promote VFA accumulation in anaerobic digesters.