Salinity tolerance and nutrient uptake of the freshwater microalga Scenedesmus protuberans

Abstract

Global warming have been serious problems worldwide. They have resulted in the saline intrusion reaching farther into the inland water system region, which negatively influences the aquatic environment and ecosystems. Our study assessed the tolerant capacity of a freshwater micro-alga, Scenedesmus protuberans, isolated from Vietnam to the salinity of 2 ‰, 4 ‰, and 8 ‰. We also evaluated the nitrate and phosphate uptake by the alga in different salinity of 0 ‰, 2 ‰, and 4 ‰. To address these two research questions, two experiments were conducted. The first experiment spanned 12 days and aimed to assess the salinity tolerance capacity of S. protuberans. The second experiment lasting for 20 days focused on investigating the nutrient (nitrate and phosphate) uptake by the alga under three different salinity levels. In the first experiment, we found that the S. protuberans could adapt and grow at the salinity up to 4 ‰ of incubation. In the second one, the micro-alga in the salinity of 0 ‰, 2 ‰, and 4 ‰ could uptake 88 %, 75 %, and 54 % of phosphate and remove 39 %, 56 %, and 36 % of nitrate from the water environment, respectively. Our results reveal a high potential for developing and validating the nutrient removal capacity of S. protuberans when applied to treat nutrients in polluted water, both in freshwater and brackish water systems, aligning with the net zero emission approach.