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Last update: May 2021

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Christian Del Valle Velasco - Study and modelling of nutrient recovery (N and P) from digestate

Christian Del Vallé Velasco - Study and modelling of nutrient recovery (N and P) from digestate
Supervisors : Fabrice Beline, UR OPAALE INRAE Rennes France and Céline Vaneeckhaute, Université Laval, Québec, Canada

Title : Study and modelling of nutrient recovery (N and P) from digestate combining P precipitation and microalgae production processes

Anaerobic digestion is more and more used in France. However, the management of digestates remains a difficulty for such a development and a major element in the environmental balance. Despite a slight increase in the homogeneity of the product after anaerobic digestion, the high volatility of nitrogen, the complexity of the product and the dilution make it difficult to use it, resulting in a low efficiency of nutrient recycling. Further transformations are needed to increase the efficiency of this recycling. In this context, the combination of phosphorus precipitation and microalgae culture processes appears to be a complementary pathway to anaerobic digestion. Indeed, the combination of these processes allows to recycle nitrogen and phosphorus, to produce compounds with an interesting added value. Moreover, both processes have synergies. The objective of this thesis is therefore to study this combination of processes for nutrient recovery from digestates through modeling and experimental works. The impact of inputs and operating conditions on the N / P ratio along the processes and the impact of this N / P ratio on the bacterial / microalgae interactions and the associated nitrogen dynamics will be studied. The modeling of the whole process will lead to an overall optimization in order to improve the efficiency of nutrient recycling.