Development of a microalgal automated cultivation system on Tetradesmus obliquus
Authors: Andres Philip Mayol, Aristotle T. Ubando, Emelina Mandia, Dion Michael M. Mendoza, Edwin Sybingco, Alvin B. Culaba and Elmer Dadios
Abstract
An automation system for various applications has been proven to be effective in attaining productivity and efficiency. Moreover, it can be used in monitoring biological culture growth parameters. Microalgae have been a potential source of food, cosmetics, pharmaceutical, and fuel. However, monitoring the growth parameters of microalgae such as the pH level, salinity, dissolved oxygen, and its color density over time has not yet been achieved in previous studies. This paper presents an automated monitoring system for a closed microalgae photobioreactor. Contemporary continuous monitoring of bioprocesses can be challenging, considering parameters crucial to the growth of microalgae, such as pH and dissolved oxygen. Dissolved oxygen, pH, and salinity sensors are installed on the system and are programmed using LabVIEW to take measurements at regular intervals. The set-up includes a vision system to monitor the changes in the color of the solution, corresponding to the population growth of the microalgae cells. Optical density readings are also done to characterize the growth of the microalgae organisms to serve as a benchmark for the experiment results. The system is employed and tested on Tetradesmus obliquus (Turpin) M.J.Wynne species, also known as [syn. Scenedesmus obliquus (Turpin) Kützing]. Results show that the optical density readings increased at a value of 0.025 in day 1 to the value of 0.27 in day 27 and ended at 0.24 in day 29. This correlates with the increasing values of the RGB values. Hence, the development of a vision system can be used in monitoring algal growth with respect to its change of color.