Dynamics of fines/bacterial cells accumulation in trickle-bed reactors/bioreactors—Multiscale modeling framework

Modeling the dynamics of fines/bacterial cells accumulation in gas–liquid–solid reactors/bioreactors is a difficult task which demands an improved understanding and quantification of the complex fluid dynamics, surface physical and microbiological phenomena coupled with (bio)chemistry and thermodynamic backgrounds. This contribution is offered as a step in that direction and presents two case studies with reference to modeling the complex physical and biological plugging/clogging phenomena in trickle-bed reactors/bioreactors, induced, respectively, by the retention of fine particles and by the formation of an excessive amount of biomass. The complex gas–liquid flow and space–time evolution of fines/bacterial cells capture, aggregation, detachment and migration in trickle-bed reactors/bioreactors were analyzed after a mathematical description was cast in terms of Euler–Euler two-fluid dynamic models based on the volume-average mass and momentum equations developed for multiphase systems coupled with species balance equations, solid deposit/biomass dynamics equations, filtration equations for the fines/bacterial cells and the aggregates, population balance equations for the fines/bacterial cells agglomeration.