Microalgae Chlorella as a Sustainable Feedstock …
99
Fig. 10 The production cost
of microalgal-based
bioethanol (Jambo et al.
2016)
cultivated in Jaworski’s Medium (JM) cultivation to observe the optimum growth of
the microalgae so that the most suitable period to harvest the cell can be determined.
From the observation, day 6–15 were found to be the best time for harvesting. Among
the different conditions studied, acid hydrolysis carried out under the condition of
2.0 M sulphuric acid and 130 °C for 30 min gave the highest concentration of glucose
which was 5.382 ± 0.063 g/l. Hence, these conditions are said to be the optimum
condition for acid hydrolysis of microalgae Chlorella sp.
On the other hand, yeast cell growth monitoring is also crucial to determine the
exponential phase of the yeast cells as the maximum rate of cell division was achieved
during this phase. Subsequently, during this phase, it is expected that it permits the
maximum utilization of available glucose in the hydrolysate so that maximum ethanol
yield could be achieved. Experimental results showed that the most optimum growth
of yeast cells can be observed between 6 and 15 h. During this period, the yeast cells
are most suitable to be harvested for the fermentation process. Among the different
yeast inoculum concentrations used in the fermentation process, 15% v/v showed the
highest ethanol concentration and ethanol yield which were 1.126 g/l and 0.209 g/g
glucose, respectively. The time course of bioethanol fermentation was also studied
by collecting the samples at different period of time. A duration of 24 h was found
to be the optimum for maximum bioethanol production with ethanol concentrations
of 1.020 g/l and ethanol yield of 0.190 g/g glucose.
In a nutshell, this study provides new information especially on the laboratoryscale bioethanol production from microalgae Chlorella sp. Future research can be
conducted by using immobilized yeasts in the fermentation processes to improve the
99
Fig. 10 The production cost
of microalgal-based
bioethanol (Jambo et al.
2016)
cultivated in Jaworski’s Medium (JM) cultivation to observe the optimum growth of
the microalgae so that the most suitable period to harvest the cell can be determined.
From the observation, day 6–15 were found to be the best time for harvesting. Among
the different conditions studied, acid hydrolysis carried out under the condition of
2.0 M sulphuric acid and 130 °C for 30 min gave the highest concentration of glucose
which was 5.382 ± 0.063 g/l. Hence, these conditions are said to be the optimum
condition for acid hydrolysis of microalgae Chlorella sp.
On the other hand, yeast cell growth monitoring is also crucial to determine the
exponential phase of the yeast cells as the maximum rate of cell division was achieved
during this phase. Subsequently, during this phase, it is expected that it permits the
maximum utilization of available glucose in the hydrolysate so that maximum ethanol
yield could be achieved. Experimental results showed that the most optimum growth
of yeast cells can be observed between 6 and 15 h. During this period, the yeast cells
are most suitable to be harvested for the fermentation process. Among the different
yeast inoculum concentrations used in the fermentation process, 15% v/v showed the
highest ethanol concentration and ethanol yield which were 1.126 g/l and 0.209 g/g
glucose, respectively. The time course of bioethanol fermentation was also studied
by collecting the samples at different period of time. A duration of 24 h was found
to be the optimum for maximum bioethanol production with ethanol concentrations
of 1.020 g/l and ethanol yield of 0.190 g/g glucose.
In a nutshell, this study provides new information especially on the laboratoryscale bioethanol production from microalgae Chlorella sp. Future research can be
conducted by using immobilized yeasts in the fermentation processes to improve the