World Aquaculture Singapore 2022

November 29 - December 2, 2022




Farahin Abd Wahab*, Razif Harun, Divyashini Mohan, Abdulrahman Ahmed Qanaan, Quin Emparan, Yoshiki Takayama, Masahiro Otake, Natrah Ikhsan, Fatimah Md Yusoff, and Tatsuki Toda



Department of Chemical and Environmental Engineering,

Universiti Putra Malaysia,

43400 UPM Serdang, Selangor Malaysia


Various outdoor microalgae cultivation systems have been designed and optimized for outdoor microalgae culture such as open raceway pond, horizontal, vertical tubular, flat panel photobioreactors, etc. However, the production of high microalgae biomass under outdoor cultivation is influenced by several abiotic and biotic factors, which impact its profitability and sustainability. This study aims to evaluate the factors affecting the production of microalgae, Isochrysis galbana, using an outdoor scale-up multiple bags reactor system installed under Malaysia’s tropical conditions. The outdoor scaled-up multiple bag reactor systems is a novel, low-cost, low-energy closed photobioreactor deployed on the water’s surface, which can cool the reactor evenly. Designed with a closed system, it reduces contamination risks, which is a clear advantage for producing high-value microalgal biomass. Two parameters were investigated, including the effects of i) inoculation ratio to the culture volume (15 to 50% v/v) and ii) cultivation mode (batch and continuous). Based on the preliminary investigation, the 15% of inoculation ratio showed the maximum specific growth rate (0.99 day-1) compared with the 33% (0.68 day-1) and 50% (0.09 day-1) inoculation ratio. However, the 15% inoculation ratio required a longer time (eleven days) to achieve the maximum growth compared to 33% (8 days). Considering the cultivation cost, energy, and contamination risk, the 33% sample was chosen as the best inoculation ratio for the cultivation mode experiments. The results showed that the semi-continuous mode achieved a higher specific growth rate (0.943-1.02 day-1) than the batch mode (0.68 day-1). Also, the semi-continuous culture provides higher quality biomass composition than the batch culture. Overall, the biomass productivity level achieved in this study which is in keeping with that of existing outdoor cultivation technologies endorses the system and offers a promising technology for outdoor microalgae mass production. 

Keywords: outdoor cultivation; closed multiple bag photobioreactor system; Isochrysis galbana, inoculation concentration; cultivation mode