Trond's PhD. project was concerned with the capture and release of flowing biomass on high voidage fibre networks, which is relevant in a number of areas including filtration and biomass growth on scaffold structures.
Experiments were carried out using a micro scale visualisation flow cell and laboratory scale filter apparatus, both with similar hydrodynamic conditions, in order to (respectively) establish:
- The predominant modes and mechanisms of biomass deposition during steady flow.
- The efficacy of oscillatory fluid flow for the re-suspension of deposited biomass.
In addition, numerical simulations were used to elucidate the flow hydrodynamics through a fibre network.
The micro flow cell visualisation used a Laser Scanning Confocal Microscope to give in-situ recording of 3-dimensional image stacks during deposition of biomass in the flow cell. By quantitative image analysis, both the local void fraction and surface area exposed to flow may be estimated from the image stacks. The laboratory scale filter apparatus give the overall filtration efficiency and pressure difference data, and also provide model parameters to estimate the filter coefficient as a function of the deposit level in the filter. By combining these model parameters with the image analysis results, it is possible to obtain the deposit profile in the filter bed as the filtration progresses and also the average shear stress acting on the biomass deposit as a consequence of fluid drag.