Optimisation of physical parameters and microbial community analysis of bio-hydrogen production from food waste
The demand for clean energy from renewable resources stimulates biohydrogen production from biomass as an alternative fuel to replace fossil fuel. Biohydrogen from food waste fermentation initiates clean technologies for energy generation thus provide the solution for waste treatment. However, th...
Saved in:
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English |
| Published: |
2021
|
| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/105953/1/FBSB%202011%2027%20-%20IR.pdf |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | The demand for clean energy from renewable resources stimulates biohydrogen
production from biomass as an alternative fuel to replace fossil fuel. Biohydrogen from
food waste fermentation initiates clean technologies for energy generation thus provide
the solution for waste treatment. However, the production of biohydrogen is inhibited by
hydrogen consuming bacteria and soluble metabolites. This inhibition effects can be
overcome by optimizing the physical parameters during biohydrogen production. The
objectives of this study were to establish the optimum operating parameters for
biohydrogen production from food waste in batch fermentation and to identify the main
hydrogen-producing bacteria at different controlled pH values. The batch fermentation
was conducted using 150 mL serum bottles incubated in facultative anaerobic condition.
Cooked and uncooked food waste taken from cafeterias with composition ratios of 2: 1:1 carbohydrate, protein and fiber were used as a substrate in this study. The concentration
of food waste was standardized at 25 gil carbohydrate before all the experiments was
conducted. Palm oil mill effluent (PO ME) sludge was used as a seed culture. Heat
treatment was carried out to POME sludge at 80°C for 30 minutes to eliminate hydrogen
consuming bacteria. Biohydrogen production was performed at different temperatures
(35°C, 40°C, 50°C, 55°C and 60°C), initial pH values (5, 6, 7 and 8) and various ratios
of sludge to substrate (10:90, 20:80, 30:70 and 40:60 % (v/v)). Biogas was collected
every 2 h and the composition of hydrogen and carbon dioxide in biogas was analyzed
by gas chromatography with no methane gas detected in all experiments. The highest
biohydrogen yield obtained was 83 mmol I-h/L-medium/d for the experiment conducted
at a temperature of 55°C, initial pH 7 and sludge to substrate ratio at 30:70 % (v/v). The
experiment was then studied using different controlled pH values of 5.0, 5.5 and 6.0 at
temperature of 55°C in 500 mL bioreactor. The results showed that pH 5.5 gave the
highest biohydrogen production yield (79 mmol H2/L-medium/d). Microbial cells
number was determined by using t1uorescent in situ hybridization (FISH) technique. The
quantification analysis showed that the number of Clostridium sp. from cluster I and XI
from samples after acclimatization was 2.9 x 108 cells/mL while the number of
Clostridium sp. from fermentation medium at pH 5.0, 5.5 and 6.0 were 3.6 x 108, 7.8 x
108 and 5.4 x 108 cells/mL, respectively. Clostridium sp. from cluster I and XI were
found to be dominant at pH 5.5 (92% out of the total bacteria) which corresponded to the
highest biohydrogen yield compared to the other pH values. Clostridium sp. cluster I
produce butyrate as the main metabolites while cluster XI criteria is heterogenous
includes non-spore forming and thermotolerance alkaliphiles species. Methanogens were not detected in the culture broth due to the heat treatment. Microbial profile at different
pH was also investigated using denaturing gradient gel electrophoresis (DGGE). It was
revealed that the DGGE bands belonged to uncultured Bacteroidetes, uncultured
bacterium, Caloramator australicus sp. and Clostridium sp. Thus, controlled operating
conditions were important to enhance hydrogen-producing bacterial growth for optimum
biohydrogen production. |
|---|