2011 International Conference on Alternative Energy in Developing Countries and Emerging Economies
- 31 -
Comparative Study on Production of Bio-Ethanal
from Oil Palm Trunks Sap
N. A. Halim* and C. K. M. Faizal*
*Fakulti Kejuruteraan, Kimia dan Sumber Asli Universiti, (
Malasia
)
Abstract
—
Oil palm trunk is a waste generated from the
re-plantation of oil palm trees at every 25-30 years
interval. Oil palm trunks sap contains lot of sugar and can
be directly fermented to most fermentation products. The
aims of this preliminary study was to investigate the
production of bio-ethanol using different strains of
Saccharomyces cerevisiae and also to know the effect of
different pretreatment on sap to the bio-ethanol
production from this waste. The fermentation process
using Saccharomyces cerevisiae Kyokai no.7 and baker’s
yeast Saccharomyces cerevisiae were performed in sap to
compare both strain performance. Then, the best strain
was used to ferment heat sterilized and non-sterilized sap.
Results showed that Saccharomyces cerevisiae Kyokai no.7
produced more ethanol compared to baker’s yeast
Saccharomyces cerevisiae at each time point. The
percentage ethanol conversion over total sugar reached
using Saccharomyces cerevisiae Kyokai no.7 and
Saccharomyces cerevisiae was 88.9% and 62.1%,
respectively. It was also confirmed that sap cannot be
directly fermented without sterilization due to existence of
others microorganism that competed with Saccharomyces
cerevisiae Kyokai no.7 which lowered ethanol
productivity. Highest ethanol productivity obtained in this
work was 421.42 mg/l/h at 24 h of fermentation by using
Saccharomyces cerevisiae Kyokai no.7 in sterilized sap
Index Term
-- Oil Palm trunks sap, bio-ethanol,
Saccharomyces cerevisiae
I.
I
NTRODUCTION
The natural energy resources have been consumed at
rapid rates more in the last decades thus leads to the
diminishing of this non-renewable supply. Extreme
usage of natural energy resources such as fossil fuels
resulting global warming which affect human lives and
causing environmental problem due to alleviation of
earth’s temperature [1
-2]. Substitutions of fossil fuels
with renewable energy are important to sustain energy
demand and reduce emission of greenhouse gases to our
environment.
Ethanol is the example of renewable energy that can
be derived from lot of sources. Bio-ethanol that is
derived from edible source is called first-generation bio-
ethanol while second-generation bio-ethanol is derived
from non-edible sources such as biomass. Bio-ethanol
can be used directly as a fuel or can be blend with petrol
or gasoline to form blend fuel. The production costs are
still the key impediment for the wide use of ethanol as
fuel even though the fermentative process for ethanol
production is well known [3]. Lot of researches has
been carried out to obtain the most efficient
fermentative strain, cheap and abundant carbon sources,
and also optimal fermentation conditions in order to
reduce the costs.
Different biomass for bio-ethanol production has
been studied such as bagassse, corn cob and rice straw
[4], soybean molasses at different scale [3], switch grass
and reed canary grass [5], carob pod [6], ornamental
plant red sage [7], hazelnut shell [8], sorghum [9-11]
and mahula
Madhuca latifolia L
. flowers [12-14].
Typically researches on biomass are depending on the
availability of that biomass in that place.
In Malaysia, every year there are abundant wastes
generated from our main commodity crop oil palm
including fronds, shell, empty fruit bunch, palm kernel
and trunks. The oil palm originated from West Africa
and was introduced by the British in the early 1870s to
Malaysia, then Malaya, as an ornamental plant [15].
About 10,827 thousand tons of trunks were generated
based on 4,304,914 Ha total cultivation area in 2007
where each hectare of oil palm cultivation can generated
2.515 tons of trunks when the trees are chopped at every
25 years [1]. Trunks contain lot of fermentable sugars
and lower lignin percentage compared to the other parts
of oil palm tree.
Various types of wood such as saw-wood and ply-
wood or lumber can be converted from oil palm trunk
(OPT) [16]. Although oil palm lumber has been
successfully utilized as core in the production of
blackboard, it is only partially utilized for plywood
manufacturing because only the outer part is relatively
strong to be used as lumber [16-17].The inner part is
discarded as a waste due to weak physical properties
and can be considered as important biomass in
Malaysia. The outer part of OPTs is removed to be used
for furniture industries. OPT cannot be used as building
structure due to its low specific density.
Hence, the objective of this work is to do
comparative study on bio-ethanol production from OPTs
sap by using different
Saccharomyces cerevisiae
strain
and verify the effect of sterilization to the bio-ethanol
production
.
II. M
ATERIAL AND METHODS
A. Raw material
The OPTs were freshly obtained from RISDA
Plantation in Pahang, Malaysia at high hill area during
March-May 2010. The sap was collected by squeezing
middle of trunks with press machine and kept at -20
o
C
for storage. The sap media were filtered with 9.0 μm
filter prior to use.
