A cultivation technique is important because it affects the CO2 utilization and bio­mass productivity of the microalgae. Thus, the choice of a batch, continuous, or semi-continuous mode of culture has a significant effect on the microalgae photosyn­thesis process. A batch culture of microalgae is defined as a culture period, whereas the cultivated microalgae cell is harvested at once. The batch culture requires a sim­pler design compared to a continuous culture. The batch operation usually remains the same despite increased dilution, and, once harvested, the entire culture is replaced with fresh microalgae cells and media. The continuous culture is conducted based on dilution rate. When the dilution reaches a certain point, half of the media are har­vested and replaced with new media to maintain the desired dilution, usually up to 0.67 per day. The dilution rate also affects microalgae productivity and its biochemi­cal contents (Moreno et al. 1998; Sanchez et al. 2008; Cuaresma et al. 2011).

The high number of measurements of microalgae analysis is one of the advan­tages of the batch culture (Pors et al. 2010). The batch culture also is capable of producing more biomass and biochemical compounds compared to a continuous culture (Yongmanltchal and Ward 1992; Gonzalez and Bashan 2000). However, in terms of productivity, a continuous culture has a greater yield of biomass (Carvalho and Malcata 2001).

Effective design on continuous culture system is capable to lower the production cost, about 40% than the traditional batch culture (Bentley et al. 2008; Sananurak et al. 2009). Most microalgae species that were cultivated in batch or continuous cultures do not have much effect on productivity compared to the nutrient feed con­centration, such as the nitrogen and carbon supplies. The growth rates of batch and continuous cultures are about the same (Pruvost et al. 2009). For a longer cultivation period, such as 4 months, increased production of microalgae can be achieved in continuous culture mode compare to batch culture mode (Rodriguez et al. 2010). The biomass productivity of microalgae cultivated in the continuous mode is com­parable to that in the batch mode (Ethier et al. 2011).

14.3 Conclusion

The membrane-integrated photobioreactor serves two major roles in biofuel pro­duction. The first role is to increase the mass transfer of exchange CO2-O2 gases in the photobioreactor, and the other is to enhance the photosynthetic rate of microal­gae, thereby increasing microalgae productivity. Although it has been proven that a membrane contactor can increase the mass transfer rate in the gas exchange process in a photobioreactor, the issue involving pressure drop due to fouling of the pores of the membrane has become a major challenge to the use of the membrane photobio­reactor. This problem is associated with the design parameters of the system and its operating conditions, such as operating pressure and the circulation process of the media culture. We are confident that this can be solved by conducting a numerical study through modelling and experimental work. The membrane photobioreactor system could be an extremely important device for both removing CO2 from the atmosphere and producing biomass by microalgae.

Acknowledgments This work was financially supported by the Research Grant LRGS/TD/2011/ UMP/PG/04 from Ministry of Higher Education of Malaysia. This work was also supported by the Borneo Marine Research Institute, Universiti Malaysia Sabah, Malaysia.

[1] OPBC is created under the National Biomass Strategy to accelerate development and commercialization of technologies for conversion of lignocellulosic biomass feedstock into higher — value-added uses such as biofuels and bio-based chemicals and the related technical, logistics, and social aspects.

N. Desmira (H) • K. Kuniyuki

EcoTopia Science Institute, Nagoya University, Furocho, Nagoya 464-8603, Japan e-mail: nelfad@gmail. com

[3] Morita

Department of Engineering Science, Osaka Electro-Communication University, 18-8 Hatsucho, Neyagawa 572-8530, Japan

R. Pogaku and R. Hj. Sarbatly (eds.), Advances in Biofuels,

DOI 10.1007/978-1-4614-6249-1_6, © Springer Science+Business Media New York 2013

A. H. Kamaruddin (H)

Chemical Engineering Department, Universiti Sains Malaysia, Penang, Malaysia e-mail: chazlina@eng. usm. my

N. A. Serri • S. R.A. Rahaman

Universiti Sains Malaysia, Penang, Malaysia

J. H. Sim

Universiti Tun Abdul Razak, Kuala Lumpur, Malaysia

[5] F. A. Halim

Chemical Engineering Department, Universiti Teknologi Mara, Penang, Malaysia

R. Pogaku and R. Hj. Sarbatly (eds.), Advances in Biofuels,

DOI 10.1007/978-1-4614-6249-1_8, © Springer Science+Business Media New York 2013