Effects of biomass growth on pressure drop in biofilters

grantor: University of TorontoThe effects of microbial mass accumulation and distribution in biofilter air pressure losses were experimentally studied. A model was proposed to predict pressure drop as a function of biomass concentration in a biofilter. Two bench-scale biofilters, one packed with inert porous pellets (Nova Inert®) and the other with wood chips, were operated with excess nutrients under similar conditions to treat air polluted with methanol (loading rates of 100 to 150 g methanol/m3 bed/h) and generate biomass. Uneven biomass distribution, described by localised high and low biomass concentrations in the biofilter beds, was the key factor affecting increased pressure drops due to extreme local porosity reduction by clogging. The highest pressure drops in the beds (2600 Pa/m in the wood chip biofilter and 550 Pa/m in the Nova Inert® biofilter) were caused by thick layers of biomass with high moisture content. and high extracellular polymeric substance (EPS) concentration. Pressure drop varied exponentially with the amount of biomass and bed moisture, and cumulative methanol consumption. Pressure drop increased significantly at a critical point in methanol removal and biomass accumulation. Six-fold higher pressure drops were measured in the wood chip biofilter compared to the Nova Inert® biofilter due to more biomass growth and bed compaction.M.A.Sc