Apport des mesures rhéologiques à l'étude des biomasses épuratoires granulaires anaérobies

Les travaux portent sur la caractérisation rhéologique des boues granulaires issues de bioréacteurs anaérobies. Après l optimisation des conditions de mesure, nous avons montré que le comportement rhéologique des boues granulaires anaérobies est non newtonien de type rhéofluidifiant, faiblement thixotrope. La viscosité limite est proposée comme un paramètre supplémentaire de caractérisation physico-chimique de la boue. La sensibilité de la viscosité limite aux propriétés de la boue (MES, charge de surface, granulométrie ) semble en faire un outil potentiellement capable de rendre compte, quelquesoit le réacteur utilisé, de l évolution de la boue au cours du fonctionnement du bioréacteur. De plus, l importance des interactions quantitatives et qualitatives entres granules peut être indirectement étudiée. Enfin, ce travail a montré la contribution des théories DLVO et Divalent Cation Bridging (DCB) dans les théories de granulation des boues granulaires anaérobies.The experimentations have been carried out on the rheological characterisation of granular sludges from anaerobic bioreactors. After optimisation of measurement protocol, anaerobic granular sludges display a non newtonian rheological behaviour with shear thinning properties, slightly thixotropic. Limit viscosity was proposed as additional parameter for the physico-chemical characterization of sludge. The limit viscosity is sensitive to the sludges properties and may be considered as a global parameter able to describe the sludge evolution, during anaerobic bioreactor operation and whatever the bioreactor type used. In addition, the importance of the quantitative and qualitative interactions between granules can be indirectly studied. Lastly, this work showed the contribution of DLVO and Divalent Cation Bridging (DCB) theories in the granulation theories of anaerobic granular sludge.LIMOGES-BU Sciences (870852109) / SudocSudocFranceF

Evaluation of bituminous binders miscibility for warm-mix recycling techniques

BCRRA 2017, Tenth international Conference on the Bearing Capacity of Roads, Railways and Airfields (), ATHENES, GRECE, 28-/06/2017 - 30/06/2017In the road industry, the current challenge is to produce at lower manufacture temperatures asphalt mixtures incorporating Reclaimed Asphalts (RA). However, the incorporation of cold RA could lead to a non-remobilization of the RA aged binder by the virgin one. A double coating appears, what leads to a binders non-mixture and poorer mechanical properties of asphalt mixtures. The objectives are to develop methods to understand remobilization mechanisms and precisely how the virgin binder comes into contact and diffuses into the RA binder. The temperature influence was investigated. Results show that contact angle measurements and micro X-ray fluorescence have been successfully adapted to the 'bitumen/bitumen' interface and interphase study. The RA temperature governs the remobilization initiation phase and influences the blending zone dimension. Therefore, RA should be heated before their incorporation in order to avoid a non-remobilization and guarantee favorable conditions to obtain homogeneous recycled asphalt mixtures with high mechanical performances