Microbubbles are known for their many applications. Recently there has been new findings regarding the growth of susceptible microalgae through microbubble aeration. There are three methods used to generate microbubbles for this microalgae strain. Unfortunately, for some methods, the cost of generating microbubbles is still high. However, fluidic oscillators can be used to produce microbubbles at a reasonable cost. There are two types of fluid oscillators: single loop and double loop. This study determined the bubble size produced with these oscillators. Bubble size data was recorded using a high-speed camera at air flow rates of 6 LPM, 9 LPM, 12 LPM, and 15 LPM, and utilized 10 µm microporous shafts as the diffuser. The data were processed using ImageJ software. The results showed that the size of the bubble using a single loop fluid oscillator was smaller than that of the double loop fluid oscillator. The smallest bubble size was obtained in a single loop fluid oscillator with an airflow of 6 LPM.

The capacity of fossil fuel production is decreasing through the years. Energy diversification is needed to solve this problem. Microalgae is one type of microorganism that has the potential as an alternative fuel. Large scale microalgae cultivation utilizes photobioreactors with aeration of microbubbles. One method to produce smaller bubbles uses a fluid oscillator. This study aims to analyze if there is any effect of the bubble size difference on Synechococcus HS-9 growth. Bubble formation utilizes a double loop fluid oscillator and continuous flow. Bubble size data is taken using a high-speed camera at 6 lpm and 10 µm micro porous shafts and processed through image processing using imageJ application. Synechococcus HS-9 growth data is taken daily optical density by using spectrophotometer. The result showed double loop fluid oscillator produces smaller bubbles than the conventional bubble aeration, thus affects a higher growth of Synechoccus HS-9. Synechococcus HS-9 growth is higher in oscillating flow conditions than in continuous flow.