Microalgae culture for extraction of nutrient from digestate was studied at laboratory scale to determine the influence of turbidity of influent, light provided, N:P of the influent, CO2 supplementation and solid retention time on microalgae productivity and associated N removal processes. The experimental results obtained in batch and semi-continuous mode showed the importance of turbidity of influent combined with light intensity on the microalgae roductivity compared to the impact of the level of CO2 supplementation and N:P ratio. Additionally to N assimilation by microalgae, nitrification-denitrification was identified as a major N pathway with N removal at least equal to N assimilation. However, limitation of nitrification process appears possible through the N:P ratio of the influent. The evolution of microalgae communities observed during these trials highlighted the interest of using mix culture allowing a better adaption to the conditions evolutions. Finally, all experimental results were used to build and calibrate a model simulating microalgae growth using nutrients from digestate and such a model was used to design a raceway pond treating digestate from a commercial farm producing 4000 pigs per year.