Effect of temperature on ammonium removal in Scenedesmus sp.

• Ratkowsky’s model accurately reproduced the temperature effect on ammonium removal.
• Cardinal temperatures model (CTM) obtained analogous results as Ratkowsky’s equation.
• The CTM is preferred due to the biological significance of its parameters.
• The obtained theoretical optimum temperature for ammonium removal was 31 °C.

The effect of temperature on microalgal ammonium uptake was investigated by carrying out four batch experiments in which a mixed culture of microalgae, composed mainly of Scenedesmus sp., was cultivated under different temperatures within the usual temperature working range in Mediterranean climate (15–34 °C). Ammonium removal rates increased with temperature up to 26 °C and stabilized thereafter. Ratkowsky and Cardinal temperatures models successfully reproduced the experimental data. Optimum (31.3 °C), minimum (8.8 °C) and maximum (46.1 °C) temperatures for ammonium removal by Scenedesmus sp. under the studied conditions were obtained as model parameters. These temperature-related parameters constitute very useful information for designing and operating wastewater treatment systems using these microalgae.