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Thesis Title Hydrogen and Methane Production by Two-stage Anaerobic
Co-digestion of Palm Oil Mill Effluent and Ceratophyllum
demersum
Author Miss Nikannapas Usmanbaha

Major Program Applied Chemistry
Academic Year 2015

ABSTRACT

The aim of this research project was to utilize palm oil mill effluent (POME)
co-digesting with Ceratophyllum demersum for hydrogen and methane production by

using the two-stage anaerobic process in both batch and continuous mode. In batch
cultivation at the initial organic concentration of 10 g-VS/L, various POME: C. demersum
mixing ratios (VS Basis) of 10:0, 9:1, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, 2:8, 1:9 and 0:10 were

investigated under thermophilic (55°C) and mesophilic (35°C) conditions for the first stage
and the second stage, respectively. Highest hydrogen production yield of 65.35±3.37
mL-H /g-VS added was obtained from POME: C. demersumratio of 9:1 (VS basis), which is 19%
2
and 58% higher than that from single fermentation of POME and C. demersum,
respectively. Subsequent methane production yield of 360.7±18.0 mL-CH /g-VS added was
4
achieved from hydrogenogenic effluent from POME: C. demersum ratio of 9:1 (VS basis).
The two-stage anaerobic process for continuous hydrogen and methane production was
subsequently investigated in the Continuous Stirred Tank Reactor (CSTR) operated under

thermophilic (55°C) conditions and Plug Flow Reactor (PFR) operated at ambient condition,
respectively. Specific hydrogen yield of 81±1.2 mL-H /g-VS added using 10% of VS from
2
C. demersum concentration in a mixed-substrate was obtained by operating at hydraulic
retention time (HRT) of 2 days and methane yield of 424±4.6 mL-CH /g-VS added was
4
obtained by operating PFR at a hydraulic retention time (HRT) of 30 days. Dominant
hydrogen-producing bacteria in CSTR were Clostridium sp. and Enterobacter sp. Existance
of Weissella sp., Leuconostoc sp. and Lactobacillus sp. could possibly cause lowering
hydrogen production. Meanwhile, PFR broth was dominated with methanogens of

Methanocorpusculum sp., Methanothrix sp. and Methanoregula sp. Hydrogen and
methane yields of 4.13 L-H / L substrate and 23.15 L-CH /L satisfactory obtained from
2
4 substrate
the continuous two-stage anaerobic process could be enable potentially for scale-up this
two-stage process to the industrial scale. This research work thus demonstrated a novel

and feasible approach for co-digesting POME with C. demersumto generate valuable
gaseous biofuel, mixed hydrogen-methane gas, efficiently.