| Summary: | Treatment of fatty materials for biogas production through anaerobic digestion
is often hampered by long chain fatty acid (LCFA) accumulation which could inhibit
both in acetogenesis or methanogenesis phase. A prevention method was tested in
this study, a bioreactor including encased digesting bacteria for biogas production
was developed, and its performance against LCFA (Palmitate, Stearate, and Oleate)
was examined and compared with traditional digestion reactors using free cells.The
thermophilic cells (3 g) were encased and sealed in 3 � 6 cm2 polyvinylidene fluoride
(PVDF) membrane with a pore size of 0.1 μm, and then were placed in batch reactors
contain synthetic nutrient and LCFA at three different concentration (1.5 g/L, 3.0 g/L,
and 4.5 g/L) as a model inhibitor. Methane production, percent reduction of methane
production, volatile fatty acids (VFA) concentration, and pH level were measured.
The methane production results shows that using of cells encased in PVDF membrane
in anaerobic digestion process gave higher tolerant capacity of cells against LCFA as
inhibitor, compared to free cells. Encased cells could be tolerant to 3.0 g/L palmitate,
1.5 g/L stearate, and 1.5 g/L oleate while free cells couldn�t be tolerant to the addition
of 1.5 g/L palmitate, stearate, and oleate. These results are also supported by VFA
concentration and pH level results. VFA accumulation and acidification due to low
pH level, which showed that the process run in imbalanced condition, had lower
occurrence rate in process using encased cell than another process using free cells.
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