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Place Amphithéâtre Blandin, Laboratoire de Physique des Solides, 510 rue André Rivière, 91400 Orsay

PhD thesis defence by Gauthier Leclercq

Gauthier Leclercq, doctorant de l'équipe OMEIR, sous la direction de M. Mohend Chaouche, Mme Fatma Briki, Mme Yasmine Kaci

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Biomineralization treatment of sewage sludge biochar for its incorporation in low carbon cementitious materials 

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dépôt de cristaux de CaCO3 sur une particule de biochar

Biochar is considered to have a negative carbon footprint.  Its use as a supplementary cement material could be of major importance to lower CO2 impact of cementitious materials. It is however still limited, usually leading to strong degradation of the material properties, including its rheology. In this thesis, we considered to evaluate the impact of surface modification of biochar particles by depositing a thin layer of CaCO3, thanks to a bio-precipitation process using the ureolytic strain Sporosarcina pasteurii. The influence of different parameters such as bacteria concentration, urea/calcium concentration and agitation has been studied to optimize CaCO3 deposition. We managed to cover first a sand surface with a thin and uniform CaCO3 layer. These conditions were next applied on sludge biochar particles. We could obtained similar treatment quality when treating particles of comparable size than the sand. The treatment of finer particles has however proven to be more difficult to implement, due to an aggregation of particles in a high-ionic strength precipitation medium. 

Composition du jury :

  • Marielle Guéguen Minerbe, Université Gustave Eiffel, Chargée de recherche, Rapporteur et Examinatrice
  • Arnaud Perrot, Université Bretagne Sud, Professeur des universités, Rapporteur et Examinateur
  • Filipa Lopes, Université Paris-Saclay, CentraleSupélec, Professeur des universités, Examinatrice
  • Farid Benboudjema, Université Paris-Saclay, ENS Paris-Saclay, CentraleSupélec, Professeur des universités, Examinateur
  • Abdlehak Kaci, CY Cergy Paris Université, Professeur des universités, Examinateur