Nighttime aeration mode enhanced the microalgae-bacteria symbiosis (ABS) system stability and pollutants removal efficiencies

• Published in: The Science of the total environment 2020-11, Vol.743, p.140607-140607, Article 140607
• Main Authors: Zhang, Han, Gong, Weijia, Jia, Baohui, Zeng, Weichen, Li, Guibai, Liang, Heng
• Format: Article
• Language: English
• Subjects: CO2 stripping; Inorganic carbon competition; Microalgae-bacteria symbiosis; Nighttime aeration
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2020.140607

Utilizing external aeration to enhance the performance of microalgae-bacteria symbiosis (ABS) system has been extensively studied. However, inappropriate aeration damaged ABS system stability. A nighttime aeration mode (NA-ABS) in different aeration intensities (20, 50, 100 mL/min) was adopted to compare to continuous aeration microalgae-bacteria symbiosis (CA-ABS) mode and no-aerated mode on pollutants removal efficiencies and system stability. Results showed that NA-ABS system performed better on total organic carbon (TOC), NH4+-N, total nitrogen (TN) and PO43− removal than CA-ABS system, especially under the aeration intensity of 20 mL/min (NAI20), with the removal efficiencies of 96.59%, 99.18%, 90.30% and 89.16%, respectively. These results were because NA-ABS system prevented CO2 stripping and provided more dissolved inorganic carbon (DIC) for the microalgae growth. Furthermore, less CO2 stripping released the competition between microalgae and autotrophic bacteria for the DIC, leading to a more stable ABS system during long-term operation. This paper suggested that NA-ABS system would provide some new insights into ABS system and be helpful for further study. [Display omitted] •Nighttime aeration (NA) modewas design.•NA has dramatic pollutants removal rate than no-aerated mode.•NA mode alleviates the competition between algae and nitrifying bacteria for inorganic carbon