While some studies have shown the capacity of microalgae to grow on digestate, only a few have looked at optimising the process, and, more precisely, increasing the digestate uptake by microalgae. Indeed, digestate is characterised by a high turbidity and pH [12; 13; 14], as well as a high particle content, which can decrease the light availability and consequently disturb the photosynthesis process and thus microalgal growth [15]. Additionally, the wide range of feedstocks used in the AD industry result in a variety of digestates with very different compositions [16; 17]. Therefore, there is a need to tailor specific nutrients to suit microalgal growth requirements. Different strains of microalgae can also have different abilities to uptake digestate, demonstrating the need to screen specific strains for different types of digestates, allowing for the optimisation of the bioremediation process.  
The value of digestate for microalgae cultivation lies in its high nitrogen content, and, more specifically, ammonium, which is the preferred nitrogen source for microalgae; indeed, the metabolic cost to process ammonium into organic matter is lower than for other forms of nitrogen [18; 19]. However, ammonium is also known for its tendency to evaporate, reducing the availability for microalgae [20]. Indeed, the volatilisation of ammonium is a common phenomenon in cultures of microalgae grown on digestate due to the high pH environment caused by both digestate, which has a naturally elevated pH, and microalgal growth, which increases the pH in cultures during respiration. This combined effect results in a shift in ammonium from a liquid to gaseous form [21]. Consequently, the pH should also be considered when using microalgae to remediate digestate, as this factor could play an essential role in improving the ammonium uptake by microalgae, and therefore digestate remediation.  
Beyond remediation purposes, growing microalgae on digestate also has significant potential in providing high-value products for an array of industries, such as the animal feed or biofertiliser and biostimulant sectors [22; 23; 24; 25]. Indeed, within the context of a circular economy, it is crucial to generate value from the biomass grown using waste nutrients from digestate, contributing to reducing the production cost of microalgal systems. However, strain screening for specific digestates while looking closely at the biomass composition has been investigated only superficially, despite the tremendous potential to optimise microalgal composition by tailoring digestates.  
In the presented work, two green microalgae (_Chorella vulgaris_ and _Scenedesmus obliquus_) were selected for their ability to grow on waste products [24; 26], and were cultivated on three digestates produced from the anaerobic digestion of three different feedstocks, aiming to identify which strain would perform better on the different digestates tested. Furthermore, to improve the ammonium uptake by the microalgae (and hence remediation potential), the pH was also manipulated to avoid ammonium evaporation during culture, improving its availability for microalgal growth. Combining pH manipulation with strain and digestate screening and tailoring presents a novelty to the field of digestate bioremediation using microalgae, by aiming to improve the remediation potential using a dual approach based on abiotic and biological factors. Additionally, the composition of the generated biomass was analysed to determine if different digestates would have a different influence on the microalgal composition, bringing additional information on the potential of microalgae grown on digestate as a high-value product for further applications.