Project
Three phase flow behaviour of granular upflow anaerobic sludgeblanket reactors
Anaerobic granule-based bioreactors, such as upflow anaerobic sludge blanket (UASB) reactors are attractive technologies for effective biological purification of high-strength wastewaters, and simultaneous energy recovery in the form of methane gas. In these reactors, the biomass retention is promoted by bacterial self-aggregation into dense granules and hence the formation of a strong, active granular sludge bed becomes important for optimal operation of the bioreactors. Hydrodynamic forces are one of the key factors that affect the physical, chemical, and biological characteristics of granules, and consequently, the performance of the anaerobic process. However, their quantitative effect on granulation and mechanisms by which they affect granulation are yet to be fully understood.
Technological challenge
In UASB reactors, relative motion between liquid, gas bubbles, and granular sludge and particleparticle collisions generate normal and shear forces on anaerobic granules. As there is a continuous three-phase flow in the reactor, the hydrodynamic environment is complex. Complimentary experimental and numerical fluid mechanics methods are required to be applied in such complex
bioreactors. Therefore, the ETE lab was equipped with new advanced high-speed cameras to measure velocities and trajectories of moving particles in order to validate the numerical model. The main focus of this research is to investigate the
effect of mechanical stresses originating from both fluid-granule and granule-granule interactions on the properties of granular sludge utilizing a combination of these new advanced in situ optical tools, computational fluid dynamics (CFD), and biochemical characterization of granular sludge. In this way, we can develop operational strategies to provide a hydrodynamic condition favouring the
development of dense, strong, and active granules, which is very important for applying these technologies in practice. In this project, we cooperate with companies that market granular sludge technology.
