“…The 1 L of culture medium (NPK-medium) contained 0. Previous experiments at laboratory scale unveiled a more efficient use of urea by the microalga, as compared to other common nitrogen sources used to grow microalgae, including nitrate, nitrite, or ammonium [15,17]. Thus, the final medium was supplemented with 8 mM urea (Panreac Química Processes 2020, 8, 324 3 of 10 SLU, Barcelona, Spain) which also provides carbon to the microalga, 100 µM FeCl 3 , and pH was adjusted to 2.5.…”