A cultivation trial of Chaetoceros calcitrans in an air-lift photobioreactor

Abstract

Chaetoceros calcitrans is a marine planktonic diatom with small-sized and high-nutrient commonly used as a feed for larvae of aquatic species. In Vietnam, C. calcitrans is often cultivated from small vessels and subsequently gradually increased the culture volume to large open tanks. Although C. calcitrans is widely cultured in aquaculture hatcheries, the cultivation process is still facing many difficulties such as unstable growth, low density or collapse due to the high risk of contamination, low quality of seeding, insufficient mixing or aeration and the control of ambient conditions. This study investigated the airlift photobioreactor systems (ALPBR) for seedling cultivation of C. calcitrans. The ALPBR was constructed by using transparent glass tubes with a diameter of 32 mm, a total length of 18 m, and volume 14.5 l. The system was optimally operated at an inoculation of 0.5-0.75×10⁶ cell.ml^-1, the flow rate at 40 cm.s^-1 and the solar light intensity at 12.5 klux at a temperature of 26-28°C.  The highest cell density was at 7.65×10⁶ cells. ml^-1. The obtained results may develop a model scale-up for algae seeding and biomass production as feed for aquaculture.