Liquid mixing and solid segregation in high-solid anaerobic digesters

Hassen Benbelkacem (1, 2) , Diana Garcia-Bernet (3) , Julien Bollon (1, 2) , Denis Loisel (3) , Rémy Bayard (1, 2) , Jean-Philippe Steyer (3) , Rémy Gourdon (1, 2) , Pierre Buffiere (1, 2) , Renaud R. Escudie (3)

1 LGCIE - Laboratoire de Génie Civil et d'Ingénierie Environnementale
2 DEEP - Déchets Eaux Environnement Pollutions
3 LBE - Laboratoire de Biotechnologie de l'Environnement [Narbonne]

An experimental procedure (Residence Time Distribution technique) was used to characterize the macro-mixing of both liquid and solid phases of a laboratory-scale dry anaerobic digester using appropriate tracers. The effects of the waste origin and total solid content were studied. An increase in TS content from 22% to 30% TS (w/w) induced a macro-mixing mode closer to a theoretical Plug Flow Reactor. The segregation of particles having different densities was investigated regarding the RTD of the solid phase. Segregation of dense particles occurred at low TS content. By using different TS content and waste origins, it was also determined that the yield stress was a key parameter in the mechanism of segregation. At high yield stress, dense particles were more stable and thus less subjected to settling. As a consequence, operating at high TS content may permit to prevent the sedimentation of the denser particles. (C) 2013 Elsevier Ltd. All rights reserved.

Mots clés: high solid anaerobic digestion; mixing; sedimentation; total solid content; residence time distribution; mass transfer; bed reactor; wastes; rheology

Domaines: Sciences du Vivant [q-bio]; Sciences de l'environnement

Hassen Benbelkacem, Diana Garcia-Bernet, Julien Bollon, Denis Loisel, Rémy Bayard, et al.. Liquid mixing and solid segregation in high-solid anaerobic digesters. Bioresource Technology, 2013, 147, pp.387 - 394. ⟨10.1016/j.biortech.2013.08.027⟩. ⟨hal-02651849⟩