Effect of Soluble Microbial Products on Simultaneous Nitrification-Denitrification in MBRs

摘要

Previous work on MBR (Holakoo et al., 2007) reported nitrogen removal via simultaneous nitrification and denitrification (SND) to be unstable despite steady state conditions and the concentrations of soluble microbial products (SMP) in MBR were found to vary up to 60% of the average value. The results of the present study showed that oxygen transfer efficiency (Kia) is a function of the mixed liquor suspended solids and SMP concentrations with improved K^ at lower biomass and higher SMP concentrations. Under limited DO conditions, the reaction rate inside the floe changes with KLO and while nitrification is enhanced at higher K^ SND decreases. Therefore, in order to achieve a reliable and stable SND in MBRs, a very tight DO control or other means of DO control such as control based on the activity of anoxic enzyme could be a more viable option. This might necessitate spatial arrangement of membranes or compartmentalization of submerged MBR tanks for a better DO control.