Exploring the relationship between viscous bulking and ammonia-oxidiser abundance in activated sludge: A comparison of conventional and IFAS systems

Nitrogen removal in a moving bed membrane bioreactor for municipal sewage treatment: Community differentiation in attached biofilm and suspended biomass

“…1A and B). These orders of magnitude were in concordance with those previously reported in conventional activated sludge (CAS), MBR, sequencing biofilm batch reactors (SBBR), and integrated fixed-film activated sludge systems (IFAS) [9,16,17,24,25]. Similar results were also reported for a MBMBR by Liang et al [26], however, these authors only investigated the SB fraction.…”

“…Onnis-Hayden et al [8], using fluorescence in situ hybridisation (FISH), demonstrated that in an IFAS the abundance of AOB and NOB was clearly higher in the attached biomass, suggesting that most nitrifiers occurring in SB were originated from biofilm detachment processes. On the contrary, van den Akker et al [24] reported that the number of copies of AOB gene markers per gram of biomass detected by qPCR did not vary significantly (p > 0.05) between SB and AB developed in an IFAS. In accordance with these authors, our results showed an equivalent abundance of AOB per g of biomass in both SB and AB samples in nearly all experiments.…”

Organic substrate transformation and sludge characteristics in the integrated anaerobic anoxic oxic–biological contact oxidation (A2/O–BCO) system treating wastewater with low carbon/nitrogen ratio

“…Moreover, the higher PN/PS ratio (4.18 -4.54) contributed to sludge aggregation and biogranule stability [50,51]. However, more EPS production in aerobic stage implied that sludge viscous bulking occurred easily with excessive growth of Zoogloea-like microorganisms [52,53]. In this study, the lower EPS caused by longer anoxic reaction time played an important role in changing sludge microstructure and improved the sludge settling ability.…”

Optimization of Nitrification Process by a Bacterial Consortium in the Submerged Biofiltration System with Ceramic Bead Carrier

“…Our previous study [17] demonstrated that molasses had a stimulating effect on the growth of the non-attached consortium in a liquid medium as well as the first phase of the nitrification process. The study by Akker et al [25] evaluated the abundance of ammoniaoxidizing bacteria (Nitrosomonas oligotropha-cluster) in a molassesfed fixed-film activated sludge. It was shown that an excess of molasses could decrease the concentration of ammonium-oxidizing bacteria present in the reactor [25].…”

“…The study by Akker et al [25] evaluated the abundance of ammoniaoxidizing bacteria (Nitrosomonas oligotropha-cluster) in a molassesfed fixed-film activated sludge. It was shown that an excess of molasses could decrease the concentration of ammonium-oxidizing bacteria present in the reactor [25]. In turn, other source of organic carbon, i.e., urea, was shown to stimulate the growth of ammonia-oxidizing communities and the process of nitrification as a whole [26].…”