Background: Biohydrogen effluent contains a high concentration of volatile fatty acid (VFA)mainly as butyric, acetic,
lactic and propionic acids. The presence of various VFAs (mixture VFAs) and their cooperative effects on two-stage
biohythane production need to be further studied. The effect of VFA concentrations in biohydrogen effluent of palm
oil mill effluent (POME) on methane yield in methane stage of biohythane production was investigated.
Results: Themethane yield obtained in low VFA loading (0.9 and 1.8 g/L) was 15–20% times greater than that of high
VFA loading (3.6 and 4.7 g/L). Butyric acid at high concentrations (8 g/L) has the individual significantly negative
effect the methane production process (
P < 0.05). Lactic, acetic and butyric acid mixed with propionic acid at a
concentration higher than 0.5 g/L has an interaction significantly negative effect on the methanogenesis process
(
P < 0.05). Inhibition condition had a negative effect on both bacteria and archaea with inhibited on
Geobacillus
sp.,
Thermoanaerobacterium thermosaccharolyticum
,
Methanoculleus thermophilus
and
Methanothermobacter delfuvii
resulting in low methane yield.
Conclusion: Preventing the high concentration of butyric acid, and propionic acid in the hydrogenic effluent could
enhance methane production in two-stage anaerobic digestion for biohythane production.
