In this stage, the SF was fed into the system. The initial
OLR was 1 kg-VS m3 day1 over a period of 10 days and
gradually increased to 1.8 kg-VS m3 day1
, at which it
was maintained for 17 days. The objective of this low
OLR was to develop a suitable biomass of flocculent
organisms in the methane fermentation reactor before the
higher OLR was performed (Fischer et al., 1981). During
this start-up phase of operation, the biogas production
increased gradually from 600 to 2500 L day1
, and methane
content increased from 62% to 76%. Ammonia concentration
in the methane fermentation reactor increased
gradually from 500 to 1500 mg L1 with an increase of
the ammonia concentration in the fed source materials,
higher than that in the source material from day 20. The
TS, VS, and COD in the digested effluent varied with those
in the source materials, but remained less than those in the
source materials.
Cons