Surface activity of biomolecules released from microalgae harvested by ozone-flotation

This paper evaluates the relation between the efficiency of harvesting microalgae biomass or biomolecules (proteins, lipids and carbohydrates) and the surface activity of the amphiphiles released during the harvesting process. Microalgae cultivated in wastewater was evaluated using a laboratory scale ozone-flotation reactor. Applying the highest biomass concentration (1800 mg/L) and a flow ratio gas-liquid of 3, recovered 79% biomass with a maximum yield of 7.6 mg biomass/mg O-3 and a release of biomolecules greater than 70%. Adjusting surface pressures of the harvested samples to integrated Gibbs model indicated that longer ozone than 19 min exposure times caused a decrease in the hydrophobic region of the molecules. This affected the efficiency of the amphiphiles present in the sample, requiring a higher concentration (from 534.72 +/- 9.63 mg/L to 1542.45 +/- 5.66 mg/L) to reduce the surface tension to the minimum values obtained (45.26 +/- 0.73 mN/m). In conclusion, ozone exposure needs be closely monitored to ensure effective biomass and biomolecules separation. (C) 2022 Published by Elsevier B.V.

Automated summary

This paper evaluates the relationship between the efficiency of harvesting microalgae biomass or biomolecules and the surface activity of the released amphiphiles. The results show that longer ozone exposure time decreases the hydrophobic region of the molecules, affecting the efficiency of the amphiphiles. Therefore, monitoring ozone exposure time is necessary to ensure effective separation of biomass and biomolecules.