Influence of different substrates on the formation of biofilms in a biofilm airlift suspension reactor

The effect of different C₁ carbon substrates (formate, formaldehyde, methanol) on biofilm formation in biofilm airlift suspension reactors was studied. The biofilm structure depended on the type of substrate. There seems to be a trend that more reduced substrates or substrates allowing a lower biomass growth rate lead to more dense biofilms. Variations in detachment forces (biomass hold up and carrier concentration) during the experiments affected biofilm characteristics and detachment. Detachment of biofilm biomass under non-growing conditions was studied. The detachment experiments clearly showed that detachment of a growing biofilm is larger than for a non-growing biofilm subjected to the same detachment forces. It is hypothesized that the growth zone of a biofilm forms a more weakly attached biofilm. A trend between biofilm density and the weakly attached fraction of biomass in the biofilm was found.