Production of microalgae Nannochloropsis oculata biomass in a bubble column photobioreactor with integrated lighting through adjustment of light intensity and air flow rate

Indonesia as an archipelagic country with constant climate throughout the year has a great potential in developing marine microalgae as one of renewable resources, in which one of them is species Nannochloropsis oculata. However, cost and energy consumption problem becomes an obstacle in the development, thus a better photobioreactor design is necessary to maximize the energy efficiency and reduce the operational cost during cultivation. The growth of microalgae as a photoautotrophic organism is affected by the condition of the environment, such as light intensity, the availability of carbon dioxide, and the accumulation of oxygen. This research undergoes an analysis of the influence of light intensity and air flow rate toward the growth of microalgae Nannochloropsis oculata. Variations are done both in light intensity to 3,000 lux and 4,000 lux followed by air flow rate variations which are 1.25 L/min and 2 L/min to determine the effect of light intensity and air flow rate to the growth of microalgae, and to achieve the growth profile and the highest biomass yield of microalgae Nannochloropsis oculata. Result from the research shows that increasing light intensity to 4,000 lux and air flow rate to 2 L/min causes the biomass production to rise up to 9.49% higher which is 0.339 g/L, and it also shows a more stable growth rate trend with less decline.