Modeling light and temperature influence on ammonium removal by Scenedesmus sp. under outdoor conditions

The ammonium removal rate of the microalga Scenedesmus sp. was studied under outdoor conditions. Microalgae were grown in a 500 L flat-plate photobioreactor and fed with the effluent of a submerged anaerobic membrane bioreactor. Temperature ranged between 9.5 °C and 32.5 °C and maximum light intensity was 1,860 μmol·m⁻²·s⁻¹. A maximum specific ammonium removal rate of 3.71 mg NH₄⁺-N·g TSS⁻¹·h⁻¹ was measured (at 22.6 °C and with a light intensity of 1,734 μmol·m⁻²·s⁻¹). A mathematical model considering the influence of ammonium concentration, light and temperature was validated. The model successfully reproduced the observed values of ammonium removal rate obtained and it is thus presented as a useful tool for plant operation.