Biofilm growth and hydrodynamic behaviour in the biological plate tower (BPT) with and without hanging biomass (BPT-HB)

Abstract

Deodorization and volatile organic compound abatement from polluted air streams can be accomplished with the biological plate tower (BPT), which has proved to be a reliable alternative to biofilters and biotrickling filters. Unlike those, the BPT is a non-clogging device, with constant active surface, and steady performance, making it ideal for scale-up and modelling. The initial BPT design needed improvement for better performance. The cylindrical body (circular plates) was replaced by a rectangular cuboid (rectangular plates). Holes in the plates did augment the amount of active biomass (hanging from the holes and under the plates), without reducing the transfer of toluene from the gaseous to the liquid phase. The diminished distance between plates was well tolerated in co-current flow, allowing much higher quantities of biomass in the same reactor volume. With 18 and 14 mm spacing between adjacent plates, the BPT, with and without holes, was tested for flooding, holdup and pressure drop. Several gas and liquid flows were tested, both in co-current and counter-current. In hydrodynamic terms, the BPT-HB with co-current flow was clearly the best option. Higher stability with higher flow rates, and lower pressure drops were observed. The inoculum was obtained from wastewater plant activated sludge (petrochemical industry).

New Reactors

“…Unlike those that are mostly applied, the biological plate tower is a nonclogging device, with constant active surface and steady performance, making it ideal for scale-up and modelling. Essentially, the biological plate tower is a pile of parallel circular plates having a single hole on the border (Peixoto and Ribeiro Pinto 2012;Sercu et al 2006;Shareefdeen et al 2005). The plates are placed in such a manner that the holes will alternate (180°) from one to the next plate.…”

“…Above 90 % removal for inlet ammonium concentrations between 7.3 and 136.6 μg L −1 and up to 25 mg L −1 for toluene was observed. Peixoto and Ribeiro Pinto (2012) enhanced the performance of BPT by changing its geometry from cylindrical (circular plates) to a rectangular cuboid (rectangular plates) and testing the hydrodynamic behaviour of cocurrent versus countercurrent flows (flooding, holdup and pressure drop) with diminished distance between adjacent plates. The diminished distance between plates was well tolerated in concurrent flow, allowing much higher quantities of biomass in the same reactor volume.…”

“…The diminished distance between plates was well tolerated in concurrent flow, allowing much higher quantities of biomass in the same reactor volume. With 18 and 14 mm spacing between adjacent plates, the BPT, with and without holes, was tested by Peixoto and Ribeiro Pinto (2012) for flooding, holdup, and pressure drop. Several gas and liquid flows were tested, both in cocurrent and countercurrent flows.…”

“…Besides the three main bioreactor configurations for air pollution control, many other alternatives have been developed which are described below (Peixoto and Ribeiro Pinto 2012;Sercu et al 2006;Vedova 2008;De Bo 2000, 2002.…”