Effects of the induction of anoxia in photobioreactor on effective cultivation of Scenedesmus acuminatus under mixotrophic cultivation mode

The purpose of this study was to investigate the optimum conditions of several factors (i.e. types and concentration of acetate, aeration rate, pH control) for maximizing the mixotrophic cultivation of Scenedesmus acuminatus using acetate as an organic carbon source. When acetate was used, dissolved oxygen (DO) was quickly consumed and resulted in an anoxic condition for 52 h. Then, DO increased quickly by photosynthetic reaction. Whenever we put acetate in a reactor after DO was recovered to higher than 7 mg/L, cells were quickly grown via cell respiration, which subsequently resulted in an anoxic condition. Compared to aeration, ammonium acetate, ammonium acetate with aeration tests, the highest maximum biomass productivity of 0.73 g/L/d was obtained for pH control test with ammonium acetate dosage. From this study, we found that DO was essential for the fast assimilation of acetate and depleted DO was quickly regenerated for pH control test. From this fact, we found that pH control test with ammonium acetate dosage was the best cultivation method for Scenedesmus acuminatus under mixotrophic condition. These findings could be a useful reference for maximizing the cultivation of S. acuminatus in industrial-scale applications.

Automated summary

The study investigated the optimum conditions for maximizing mixotrophic cultivation of Scenedesmus acuminatus using acetate as an organic carbon source. Factors like aeration rate, pH control, and the type/concentration of acetate were found to significantly impact the growth of S. acuminatus. The importance of dissolved oxygen and pH control in the cultivation process was highlighted, with a particular emphasis on the use of ammonium acetate dosage for optimal growth.